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October 1999  1 Contents Vol.12, No.10; October 1999 FEATURES   4  Sharing A Modem For Internet &    Email Access WinGate provides the sharing and functions as a DHCP server and firewall into the bargain – by Greg Swain 37  Introducing Home Theatre Large-screen movie action for your lounge room – by Louis Challis 42  Internet Access – Reduced Prices No time limits, no download limits, no fine print – and no hassles 79  The Ultimate Programmable Remote Control Introducing Home Theatre – Page 37. JBL’s “Take Control” TC1000 – by Leo Simpson PROJECTS TO BUILD 16  Backup Battery For Cordless Phones Backup Battery For Cordless Phones – Page 16. Simple circuit keeps your cordless phone operating during blackouts – by Leo Simpson 24  Build The Railpower; Pt.1 A remote controlled throttle for model railways – by John Clarke & Leo Simpson 54  Semiconductor Curve Tracer Build it and display the dynamic characteristics of semiconductors on an oscilloscope – by Rick Walters 64  Autonomouse The Robot; Pt.2 Final assembly and testing – by John Clarke 82  An XYZ Table With Stepper Motor Control; Pt.6 Making the pen holder & plotting a PC board pattern – by Rick Walters SPECIAL COLUMNS 20  Serviceman’s Log Did lightning strike at all? – by the TV Serviceman 76  Vintage Radio Railpower Remote Controlled Throttle – Page 24. Jim Birtchnell and his radios – by Rodney Champness DEPARTMENTS   2  Publisher’s Letter 44  Mailbag 53  Subscriptions Form 70  Product Showcase 73  Electronics Showcase 74  Circuit Notebook 90  Ask Silicon Chip 93  Notes & Errata 94  Market Centre 96  Advertising Index Build A Semiconductor Curve Tracer – Page 54. October 1999  1 PUBLISHER’S LETTER www.siliconchip.com.au Publisher & Editor-in-Chief Leo Simpson, B.Bus., FAICD Production Manager Greg Swain, B.Sc.(Hons.) Technical Staff John Clarke, B.E.(Elec.) Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Enquiries Rick Winkler Phone (02) 9979 5644 Fax (02) 9979 6503 Mobile: 0414 34 6669 Regular Contributors Brendan Akhurst Rodney Champness Garry Cratt, VK2YBX Julian Edgar, Dip.T.(Sec.), B.Ed Mike Sheriff, B.Sc, VK2YFK Philip Watson, MIREE, VK2ZPW Bob Young SILICON CHIP is published 12 times a year by Silicon Chip Publications Pty Ltd. A.C.N. 003 205 490. All material copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Printing: Macquarie Print, Dubbo, NSW. Distribution: Network Distribution Company. Subscription rates: $69.50 per year in Australia. For overseas rates, see the subscription page in this issue. Editorial & advertising offices: Unit 8, 101 Darley St, Mona Vale, NSW 2103. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9979 5644. Fax (02) 9979 6503. E-mail: silchip<at>siliconchip.com.au ISSN 1030-2662 * Recommended and maximum price only. 2  Silicon Chip DC power in the home; would it make sense? If you refer to the battery backup project for cordless phones in this issue, you will see that I am plagued by blackouts in my home. That this should be the case in 1999 in an old estab­lished Sydney suburb is pathetic but there you are. But it got me thinking about ways to avoid the problem, assuming that it will continue into the future. In my home we can at least continue to cook during a blackout since we have natural gas but all other power-assisted activities must cease for the duration of the power failure. So you start to think about pro­viding household power which does not involve the big power items such as heating and cooking. Leave out refrigerators and washing machines which use induction motors and you are not talking about huge amount of power to be provided by batteries. Let’s say we decided we were going to limit the number of lights to several hundred watts and then we are left with equip­ment such as VCRs, TVs, computers and a host of plugpack-powered devices which run from low voltage DC. Perhaps we are only talk­ing about five to six hundred watts or so. Question is: what sort of inverter would you use? Most people would think of sinewave or modified sinewave inverters but perhaps they are not needed. Why not just have a 12V to 250DC inverter? It would be much simpler and more efficient than an AC inverter. Let’s face it: most computers, PC monitors and TV sets will run from 250V DC without any need for modifications. The DC would feed via the existing bridge rectifier straight into the switch­mode power circuitry. And incandescent lamps and compact fluores­cent lamps will happily run from 250V DC as well. That leaves just the plugpack-powered devices (heaps of them, it seems) running at 12V or so. But why would you run them from an invert­er? Why not run them at 12V DC? So the solution would be to run the TV, computer and lights at 250V DC and the lower powered devices at 12V DC, straight off the same battery bank that supplies the inverter. In effect, you would get rid of all plugpacks and run from 12V DC permanently. You would have an automatic contactor in your switchboard to switch from 240VAC mains power to the inverter’s 250V DC and you would run a 12V DC supply around the home for all the low voltage gear. There would be a small bonus too because you would elim­inate the inefficiency of running quite a few separate plugpacks. Mind you, current audio equipment, VCRs and conventional fluorescent lights will not run on DC so an AC inverter would still be required but there is no reason why future models with switchmode supplies could not run on 250V DC as well. What would be the cost of all this, to eliminate blackout-induced frustration? By the time you added up the cost of deep cycle batteries, a big inverter and all the electric wiring modifications that would be necessary, you could be up for $4000 or more, so it is hardly practical just to stop the occasional blackout is it? But a similar problem is faced by many people in remote locations who don’t have the luxury of mains power. They probably think in terms of solar panels, big batteries, DC to AC inverters and so on. Maybe the DC approach, low voltage and high voltage, is a better way to go. In some ways it would be a reversion to the early days of electricity before AC power transmission became universal. It is an intriguing thought, even if it doesn’t solve the problem of nuisance blackouts. Leo Simpson M croGram Computers Windows Terminal This windows based terminal is suitable for both NT Terminal Server & Citrix Metaframe as well as being configurable for Unix hosts. It supports Microsoft's RDP and Citrix ICA3 protocols. In addition, it also emulates a number of standard terminals. Ports provided include DB25 parallel port, two DB9 serial ports, two USB ports, VGA DB 15, PS/2 mouse & keyboard ports & audio in & out. It is used with a standard monitor, keyboard & mouse. Web-Based Training from $9.95 per month* New courses now available! Including Windows 98, Quicken 98, Lotus Notes, Internet Tools (Netscape) and more courses on TCP / IP. TCP/IP Ethernet LAN Terminal TCP/IPEthernetLANTerminalwithLPD $499 $519 10/100BaseTX Ethernet Switches Dual Speed IP Gateway Hub Cat. 10108 Year 2000 BIOS Card $699 Dual Speed IP Gateway Hub Dual Port Internet Access Server UTP/BNC Rack Mount Industrial Case (PCI/ISA) $159 $149 Even Pentium motherboards are not immune to the Y2K bug! This Year 2000 BIOS Card solves the problem of progression from 1999 to 2000 as well as 21st century leap years & also doublebuffered to take care of the Crouch-Echlin effect. Cat. 3359 Year 2000 BIOS Card $129 PCMCIA Card Drive for Desktop PC This high performance PCMCIA Drive provides two frontaccess sockets on the 3.5" front bay and connects to the Interface Adapter by cable. $559 The drive supports DOS & Windows 3.1x, WIN95/NT 3.5x & 4 and OS/2 Warp 3.0 & 4.0. Each port on these 8 & 16 port switching hubs is a 10/100 BaseTX auto negotiation port which supports half & full duplex transmission. If your network has continual collisions (with consequent drop in network performance) this hub will switch a dedicated path between the sending & receiving Providing up to 14 slots, 2 x 5.25" and 2 x 3.5" drive bays, computers thus preventing collisions and improv- this 19” case supports a number of different backplanes. ing performance and usable bandwidth. Other features include, a ball bearing cooling fan and a Cat. 11322 Ethernet Switch Hub 8 Port 10/100BaseTX $459 hold-down clamp for plug-in AT or XT cards. Accomodates Cat. 11323 Ethernet Switch Hub 16 Port 10/100BaseTX $899 either an industrial 350W or standard 300W power supply. Ultra DMA 66 HDD PCI IDE Controller The ATX case model includes a 250W ATX power supply. Cat. 2809 HDD Cont PCI IDE Ultra DMA 66 Cat. 2632 HDD Cont PCI IDE Ultra DMA 33 This card carries the NSTL "Compatibility Test" seal. A dual port Internet Access Server is also available. The second line can be set to dial when the first line reaches a nominated percentage of full load. UTP and BNC connectors are provided. Cat. 10112 Break the 8.4Gb drive barrier and get a lot more speed. Our Ultra DMA66 IDE controller with two enhanced Ultra DMA 66 IDE ports supports up to 4 IDE devices and co-resides with existing motherboard IDE ports i.e. 8 IDE devices on one computer. The performance improvement is dramatic! Now over 200 courses on offer *Full details at www.tol.com.au An internet access server and an 8 port UTP network hub all in one box. Two RS232 ports allow connection of 2 modems to provide additional bandwidth to the internet. Each UTP port is a 10/100 BaseTX auto negotiation port. All stations on the network have simultaneous access to the internet. Cat. 1214 Windows Terminal $1299 A hardware based firewall ensures security, while dial on demand minimises connect time. It also has a built in DHCP Serial and TCP/IP Ethernet LAN terminals. server. The second modem can also be configured for Cat. 1026 Serial Terminal 115.2Kbps $469 Cat. 1133 Serial Terminal 460Kbps $489 incoming calls. Cat. 1104 Cat. 1134 A number of courses are “Microsoft Certified Professional - Approved Study Guides” Cat. 6121 Cat. 6458 PCMCIA Card Drive for Desktop PC $219 PCMCIA Card Drive & FDD $399 Digital “Film” Reader/Writer Transfering images from your digital camera can be S-L-OW. These reader / writers connect to your parallel port and appear as another “drive” in Windows Explorer. Cat. 6459 Compact Flash Card Reader / Writer Cat. 6603 Smart Media Card Reader / Writer $189 $279 Remote Power Control Kit via Internet A full size industrial CPU card which supports Pentium II Celeron. It provides support for 512MB EDO/SDRAM, four IDE drives/devices, two FDD, one RS232 serial port, one selectable RS232/422/485 port, one SPP/EPP/ECP parallel port, two USB ports, VGA display & 16 level watchdog timer. Control computers, pool pumps, security lighting, heating, cooling etc. over an intranet or the internet. The kit includes a PCI PnP Digital I/O interface card, power control box & eight-in-one connecting cable. Fully functional demonstration software, with source code in VB and C++, is included as well video monitoring software. Cat 17057 Cat. 17064 Remote Power Control Kit via Internet $579 Cat. 17055 Cat. 17056 Cat. 8895 Cat. 8894 Cat. 17058 Indust. Case 19” Rack 14 slot Passive BP Passive Backplane PCI/ISA 14 slot Indust. Power Supply 350W PS/2 AT Power Supply 300W PS/2 AT Indust. Case 19” Rack 14 slot ATX M’Board $899 $229 $365 $175 $1150 Industrial CPU Card Industrial Full Size CPU Card (no CPU) $1230 E & OE All prices include sales tax MICROGRAM 1099 Come and visit our online catalogue & shop at www.mgram.com.au Phone: (02) 4389 8444 Dealer Enquiries Welcome sales<at>mgram.com.au info<at>mgram.com.au Australia-Wide Express Courier (To 3kg) $10 FreeFax 1 800 625 777 We welcome Bankcard Mastercard VISA Amex Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261 Vamtest Pty Ltd trading as MicroGram Computers ACN 003 062 100 Fax: (02) 4389 8388 Web site: www.mgram.com.au FreeFax 1 800 625 777 How to share a modem between PCs & give users simultaneous Internet access Want to share one modem and a single telephone line between multiple PCs for simultaneous email or Internet access? A proxy server such as WinGate is the answer. It also functions as a DHCP server and as a firewall into the bargain. A By GREG SWAIN COMMON PROBLEM facing many small businesses is how to provide email access for all computers on a network. Unless there are only two or three users, it’s just not practical to fit a modem to all PCs and add additional telephone lines or even have them share a single line. The cost of additional lines often cannot be justified, while a single line means that only one person can have Internet access at any one time. The answer to this problem is to have all PCs on the net­work share the same modem. This involves installing extra soft­ware on the computer with the modem, so that it functions 4  Silicon Chip as a “proxy server”. The server then routes Internet requests from the client computers through the single Internet connection, to give all machines simultaneous access. In effect, the proxy server acts as a “gateway” to the Internet (or to local web/email servers) for the client machines on the network. As far as each user is concerned, the clients all behave as if they had their own modem. In computer jargon, the proxy server behaves as though it were “transparent”. There’s just one import­ant difference – if the server is already on-line, the client has immediate access to the Internet. Conversely, if there is no existing connection, a request for Internet access from a client computer automatically initiates a dial-up session. The cost benefits of this are obvious. First, you don’t need to provide additional modems and Internet connections. Second, only one telephone call is required for all users to access their email. And third, users can access their email when ever they want, instead of waiting for the line to become avail­able. Proxy software Unfortunately, unless you have the very latest version of Windows 98 (second edition), you need third party software to provide modem sharing. That’s the bad news. The good news is that there are plenty of software proxies about and they don’t cost the earth. Of these, the best known are WinGate (www.wingate.com.au) and Sy­ Gate (www.sygate.com). In this article, we’ll take a close look at WinGate and describe how it’s set to provide modem sharing. But that’s not all WinGate can do. As well as functioning as a proxy server, it can also function as a DHCP server and as a firewall. DHCP stands for Dynamic Host Configuration Protocol and allows a server to automatically hand out IP addresses to client computers on a network as they boot up. A DHCP server makes it really easy to set up a TCP/IP net­ work, since you don’t have to manually assign IP addresses to the client computers and maintain lmhosts files. It does have one disadvantage though; if the DHCP server goes down or is switched off, the rest of the network also goes down (unless there’s a backup DHCP server). WinGate runs on both Windows 95/98 and Windows NT and works with most Internet applications. These include web browsers, FTP, news and email programs, Telnet, IRC, Real­Audio/Video and many other Internet tools and applica­ tions. It’s not restricted for use with a dial-up modem either; WinGate will function just as well with ISDN, cable modem, satel­lite connection and other dedicated circuits, and can act as a proxy for local web and email servers. Downloading WinGate If you haven’t already done so, the first step is to set up a working Internet connection on the PC that’s going to be the proxy server. Having done that, you can download the latest version of the WinGate software (Ver. 3.0.4). In Australia, you can go to the local WinGate distributor which is Jantek­ nology Distribution. Their website address is www.janteknology.com. au or www.wingate.com.au There are three versions of WinGate to choose from: Win­Gate Home, WinGate Standard and WinGate Pro. You also have to choose the correct software to suit your operating system, either Windows 9x or NT. The differences between the three versions and the pricing details are all listed on the website. For example, both WinGate Standard and WinGate Pro include a caching utility that stores previously visited pages on the Win–Gate server, for faster access if sites are subsequently revisited. They also include a “ban” utility that can restrict access to certain websites. WinGate Pro adds user management utilities. It allows the Administrator to add individual users and groups, to remotely administer the program and to carry out auditing and sched­uling. Among other things, these facilities also allow the admin­istrator to restrict individual or group access to Internet services according to custom settings. The Home version provides a simplified user interface and has minimal configuration options. It’s the one to use for shared Internet access at home or in a small office with only a few users. Fig.1: before installing WinGate, you must have TCP/IP installed for your network adapter (not just for a Dial-Up Adapter as shown here). Fig.2: to add TCP/IP to your network adapter, click the Add button and follow the prompts. This shows the entry for an SMC network adapter. Fig.3: the WinGate server must be assigned a static IP address (192.168.0.1) and a subnet mask (255.255.255.0). Fig.4: on the clients, select the “Obtain an IP address automatically” option so that they obtain their IP addresses from WinGate’s DHCP service. The cost of the software depends on the features that you want and the maximum number of simultaneous users required. At the time of writing, WinGate Home 3-User costs $67, WinGate Standard 3-User $134 and WinGate Pro 6-User $500. However, you can also choose 6-user, 12-user, 25-user, 50-user and unlimited user licences. You don’t have to pay for WinGate upfront, however. In­ stead, you can download a trial “key” which will allow you to evaluate the software for 30 days. There’s also a handy order form on the Janteknology site that you can download and send in for your full licence keys. While you’re there, you should also download the installa­ tion instructions and the WinGate User manual. Windows 95 users will also have to download the Winsock 2 upgrade but note that this is not needed for Windows 98. This upgrade must be installed on the Windows 95 client computers in order for WinGate to func­tion correctly. Server setup WinGate requires a network that’s running the TCP/IP proto­col, otherOctober 1999  5 Fig.5: Internet applications on client machines are set up to connect via a LAN instead of via a modem. This is the setting for Outlook Express. Fig.6: this is the connection setup for Internet Explorer 4. Provided you’re using WinGate 3.0 or later, any proxy settings should be as specified by your ISP. wise it won’t work. That means that you have to set up TCP/IP on each individual PC before actually installing WinGate. For the purposes of this article, we will assume that you are using Windows 95/98, although the procedure is similar for NT. Let’s deal with the server first. Because the server already has an Internet connection, TCP/IP will already be bound to the Dial-Up Adapter. What you have to do now is add the protocol to the network interface card (NIC) – if it doesn’t already exist that is. To do this, double click the Network icon in Control Panel to bring up the dialog box shown in Fig.1. If you don’t 6  Silicon Chip see a TCP/IP entry for your network card, click “Add”, double-click “Protocol” from the list, select “Microsoft”, select TCP/IP and click OK. After that, it’s just a matter of following the on-screen prompts to complete the installation. When you subsequently recheck the network configuration dialog box, you should see that TCP/IP is now bound to your network card. Fig.2 shows the entry for an SMC EZ Card PCI 10 Adapter. The WinGate Server now has to be configured with a “static” (ie, manually assigned) IP address. To do this, first double-click the TCP/IP entry for the network card to bring up the TCP/IP Properties dialog box. Select “Specify an IP Address” (under the IP Address tab) and enter in an IP address of 192.168.0.1. The Subnet Mask to use here is 255.255.255.0 – see Fig.3. Of course, there’s nothing to stop you from using a differ­ent IP address but don’t do this unless you have a valid reason (and you know what you are doing). The WINS Configuration, Gateway, Bindings and Advanced settings should all be left as they are. Similarly, the DNS Configuration should be left as is but note whether DNS has been enabled or disabled – you’ll need to know this when it comes to setting up the WinGate clients. Having set up the TCP/IP properties, you’re now ready to install Win­ Gate on the server. WinGate 3.0 and later combines both server and client software components, so it’s important to install the correct component on each machine. Because this is the first machine that WinGate is being installed on, the setup procedure automatically selects the server component for installation (you can change this if you wish, however). In most cases, you can choose the “Typical” setup option but if you choose “Custom”, it brings up a dialog box that lets you select which proxy services to install for yourself. When the installation is complete, the WinGate Engine starts automatically. This is indicated by the WinGate Engine Monitor icon which is added to the System tray (on the righthand side of the Taskbar). This icon has a little computer screen that is blue when the engine is running but turns red if the engine is stopped. Note that the WinGate Engine may take a few minutes to initialise the first time it’s started. Client configuration Unlike the server, you don’t have to manually assign IP addresses to the client computers. Why? – because we can now use the DHCP service on the WinGate server to hand out IP addresses to the clients each time they start up. By default, the DHCP service starts automatically when WinGate is installed on the server, so no user configuration is necessary. However, we’re getting ahead of ourselves. The first step, if you are running Windows 95, is to in­stall the Winsock2 upgrade. Once this has been done, you add TCP/IP to the network cards in the clients in exactly the same manner as before and then install WinGate on the client ma­chines. It’s quite easy to configure the clients to use the DHCP service. All you have to do is launch the IP Properties dialog box, click the IP Address tab and select the “Obtain an IP ad­dress automatically” option (Fig.4). The only other setting that you have to worry about here is the DNS configuration. If DNS is enabled on the WinGate server, select “Disable DNS”. Conversely, if DNS is disabled on the WinGate Server, select “Enable DNS” on the client and enter the client’s name in the Host field. This done, you have to enter the IP address(es) of your Internet Service Provider’s DNS server(s) in the “DNS server search order” field. The other fields are left blank. Once all this has been done, you should have a fully work­ing TCP/IP network, with the server now automatically handing out IP addresses to the clients. You can, of course, manually assign IP addresses to the client machines if you wish. You might want to do this in a small office network where you don’t want to rely on a DHCP server, for example. Typically, you could assign an IP address of 192.168.0.2 to the first WinGate client, 192.168.0.3 to the second client, 192.168.0.4 to the third and so on. Note, however, that the subnet mask must be the same for all machines (ie, 255.255.255.0). If you do wish to assign static IP addresses, then it’s simply a matter of following the instructions in the user manual. Be sure to follow the Fig.7: WinGate is administered using the GateKeeper program which is installed on the server. The opening screen lists the System Services that are available. instructions for the Gateway and DNS set­tings carefully. Once the TCP/IP network is up and running, WinGate can be installed on the clients. This time, the setup program automati­ cally detects the Win-Gate server on the network and selects the client component for installation. This adds an extra icon la­belled “WinGate Internet Client” to the Control Panel – see Fig.18. Normally, the WinGate Internet Client software runs in the background and is completely unobtrusive. Its job is to elim­inate complicated application setups and it does this by automat­ ically intercepting winsock calls made by the applications and redirecting them to the server. So what does all that jargon mean in practice? It simply means that you set up your email, browser and other applications in exactly the same manner as for a direct (modem) connection to the Internet (just follow the instructions given to you by your ISP). There’s just one exception – you must configure the appli­cations to connect via the LAN instead of via a modem. Fig.5 shows the setting for Outlook Express, while Fig.6 shows the setting for Internet Explorer 5. By contrast, earlier versions of WinGate (ie, before Ver. 3.0) only installed software on the server and this required special setup procedures for any Internet applications. The keeper of the gate At this stage, you will have a working TCP/IP network with WinGate installed on the server and client machines. You now need to configure WinGate to give the clients Internet Fig.8: clicking the Services tab brings up the available User Services. You configure each service by doubleclicking its entry to bring up a Properties dialog box. access and that’s where “GateKeeper” comes in. This program can also be used to restrict the rights that users have or to manually configure the various services (eg, the DHCP service). Basically, GateKeeper is the administration program for WinGate. It’s started by double-clicking the WinGate Engine Monitor icon in the Fig.9: the DHCP service can operate in fully automatic mode or can be manually configured if required. system tray of the server, or you can do it the hard way and go through the Start Menu. The first time you launch Gate-Keeper, leave the password field in the logon box blank and click OK. You will then be warned that you have no rights to the system until you enter a password. Click OK and then follow Fig.10: the DHCP Settings tab shows the IP scope – ie, the IP addresses that can be handed out to the clients. Fig.11: doubleclicking the scope address range in Fig.10 bring up the Scope Properties dialog. This lets you manually specify the scope, exclude addresses that you don’t want handed out and set the lease duration. October 1999  7 Fig.12: the Dialer service must be configured before clients can access the Internet. This involves selecting the “Connect as required” option, choosing the dialer profile from the drop-down list and filling in the username and password information. The disconnect options should also be checked as required. the on-screen prompts to enter a new password, so that you have full access to GateKeeper. Don’t forget this password; you will need it to logon to GateKeeper in the future. When you launch GateKeeper, the dialog box shown in Fig.7 appears. This lists the “System Services” that are available (DHCP, DNS, Winsock Redirector, Dialer, etc). Similarly, clicking the “Services” tab shows the available “User Services” (Fig.8); eg, FTP, WWW and POP3 (ie, email) proxy servers, etc. Configuring DHCP You configure each of the services by double-clicking its entry. For example, double-clicking the “DHCP Fig.13: the System Policies dialog is used to set global options. By default, the recipient specified is “Everyone, Unrestricted Rights” but you can add or remove recipients to suit your particular network, if required. Unlike WinGate Standard, WinGate Pro lets you add new users and groups. 8  Silicon Chip Service” entry and selecting the DHCP Mode tab displays the properties dialog box shown in Fig.9. This lets you choose between three operating modes: fully automatic, semi-automatic and manual. If you leave it in the default fully automatic mode, no further configuration is required. When this mode is used, a default gateway is automati­ cally assigned, the DNS is set to WinGate and the “Scope Proper­ties” are automatically specified. A “scope” defines the range of IP addresses that can be handed out to clients. If you select the semi-automatic mode, you can specify which components you want to manually configure. This includes assigning the gateway and DNS servers and creating scopes. If you select the manual mode, you have to specify all settings yourself. The DHCP Settings tab brings up the dialog box shown in Fig.10. This shows the address of the gateway (192.168.0.1) and the IP scope, in this case 192.168.0.1-192.168.0.254. Double clicking the scope entry brings up the Scope Properties dialog box – see Fig.11. This lets you alter the scope range and add to the excluded address list. Note that, in Fig.11, the address 192.168.0.1 has been excluded since that is the IP address of the gateway itself. Configuring the dialer This step is vital if you use a modem to access the Inter­net and you want to also give the clients access via WinGate. As before, you set up the service by double-clicking its entry. In this case, you double-click the Dialer entry in Fig.12 to bring up the Dialer Properties dialog (also shown in Fig.12). You then check the “Connect as required using” option and select the desired profile from the drop-down list. The dialog shown at the front of Fig.12 will appear and it’s now only a matter of filling in the Username and Password information for your ISP account. Leave the Domain field blank unless your ISP requires you to logon to an NT domain in order to connect to their services. By the way, it’s a good idea to increase the disconnect period from the default value to prevent WinGate from hanging up at a moment’s notice (something which can quickly become Fig.14: WinGate lets you restrict access for the recipients according to location (ie, the IP address) and the time of day. There’s also a ban list feature that allows you to ban clients from accessing web pages that match selected criteria. very annoying). In order for clients to access a service, they must be granted the right to do so. This is determined by the “policies” settings in GateKeeper. Basically, there are two levels of rights: (1) system policies; and (2) service policies. What’s the difference between them? Well, system policies allow you to define global access rights, while service policies allow you to set the rights for individual services (eg, for DHCP and POP3). The system policies dialog is access­ ed by clicking the “Users” tab in GateKeeper and then double-clicking the “Systems Policies” icon in the lefthand pane – see Fig.13. By default, the Everyone group with unrestricted rights is installed but you can delete this and add recipients of your own if you wish to re­strict access to certain users (just click the “Add” button and follow the bouncing ball). As stated previously, WinGate Pro allows you to add new users and groups, whereas WinGate Standard only identifies two user accounts named “Administrator” and “Guest” Once a recipient has been added, you can double-click its entry to bring up the properties dialog box shown at the front of Fig.13. This allows you to restrict access according to the location of the user (eg, for a single IP address or a range of IP addresses) and even to restrict access times to certain hours and certain days of the week – see Fig.14. One of the most useful tools here is the “Ban List” feature. It allows you Fig.15: the Policies tab lets you choose the default rights for the services, as specified in System Policies. Fig.16: you can also add individual recipients for each service and ignore or include the default rights. Granting access to ban the clients from accessing any web site that matches the criteria you select and this may be based on server name, the server IP address, the website name (URL) and URLs containing certain words. On the other hand, if you want to set unique policies for a particular service, click on the Services tab in GateKeeper, then double-click the icon for the service you wish to modify and select the “Policies” tab from the resulting dialog box. Fig.15 shows a typical setup for a POP3 proxy server. In this case, the “Default rights (System policies)” setting will be used. Note that the option “may be used instead” has been select­ed here, so if the systems policies setting is “Everyone, Unre­stricted Rights”, then that is the policy that will apply. Alternatively, by clicking the add button, you can add one or more recipients to suit that particular service – see Fig.16. If you can’t get the DHCP service working, check its Policies setting. Unlike other services, you cannot choose a default systems policies setting (it’s greyed out). By default, “Everyone, Unrestricted rights” should be listed in the pane but if it isn’t, you will have to add a recipient your­self. Other tabs on the service properties dialogs let you check the Bindings and Interfaces (ie, the interfaces that connections will be accepted on) and set logging options. Security That brings us to a very important function of WinGate – its ability to act as a firewall. During setup, WinGate’s installa­ t ion wizard automatically configures the system for maximum security. It does this by binding the individual proxy services to the IP address of the internal network card (192.168.0.1) and to a local “loopback” address (127.0.0.1). In operation, WinGate will only accept requests coming from this internal interface. Any requests coming from the Internet appear to be coming from an external interface and are rejected. In addition, the administrator can set up the system po­licies so that WinGate only accepts connections coming from specific address ranges. History logging One feature that will be of interest October 1999  9 Fig.17: the History logging option allows the administrator to monitor Internet activity on the clients. This could be useful for checking that business computers are only used in an authorised manner, for example. Fig.18: the WinGate Internet Client (WGIC) is launched from the Control Panel. You can use it to disable WGIC or the dialup monitor and to select which WinGate server to use if there is more than one server on the network. to administrators is the ability to log Internet activity. This could be particularly useful for monitoring user patterns and making sure that business computers are only used in an authorised manner, for example. This logged file is displayed by clicking the “History” button on the GateKeeper toolbar – see Fig.17. Naturally, the logging feature can be disabled if it isn’t required. WinGate Internet Client Normally, you don’t have to con­ figure the WinGate Internet Client (WGIC) but there are a few options for advanced users. The WGIC is opened by dou- Sharing An Internet Connection Using Hardware An alternative to using proxy server software for shared Internet access is to use a hardware proxy instead. This interesting device is called a Dual Speed IP Gateway Hub but don’t let the plain-vanilla exterior fool you – it rolls an 8-port 10/100Mb hub, an Internet access server, a DHCP server and a firewall all into one. It provides simultaneous Internet access for all users on the network and supports either one or two modems, the second modem automatically dialing in according to traffic requirements. We’ll take a closer look at this unit next month, along with its little brother Dual Port IP Gateway. In the meantime, you can obtain further information on these products (Cat. 10108 & 10112 respectively) from MicroGram Computers: www.mgram.com.au; phone (02) 4389 8444. 10  Silicon Chip ble-clicking its icon in the Control Panel. This bring up the dialog box shown in Fig.19, after which there are four tabs to choose from. The General tab allows you to enable or disable WGIC and to launch the WinGate Dialup Monitor at startup. Normally, you would want to enable the Dialup Monitor so that the client displays the dialing status during dialing and also to allow the client to send a discon­nect request to the server. The WinGate Servers tab lists all the WinGate servers that are connected to the LAN. You can choose which server to use, or you can have one automatically selected for you. On most networks, there will only be one WinGate server so you can just leave the automatic setting enabled. The other two tabs allow you to select Internet applications that you don’t want redirected through the server and to reset the WGIC protocols to their default settings. Using WinGate Once set up, WinGate is easy to use. When you attempt to connect to the Internet from a client machine, the dialup monitor appears and is subsequently minimised to the System Tray (assuming that the connection is successful). After that, you can send email or use other Internet applications in the normal manner. If the connection is already open, the dial-up process is bypassed and new clients have immediate access to the Internet. At the end of the session, you disconnect by double-click­ ing the dial-up monitor icon in the System Tray and then clicking the disconnect button. Note, however, that the server will reject any dis­connect requests if other clients are still using the connection. In short, it’s all pretty much transparent to the user. And that’s the basic idea behind WinGate – to give several users simultaneous access just as if they all had their own modems. Finally, there are lots of other features that we haven’t covered here. For example, you can run an internal mail (SMTP) server behind WinGate on your LAN and you can provide external access to your network by bypassing the proxy service. You will find all the information you need at www.wingate.com, in the Wingate SC manual and in the help files. SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.dse.com.au Backup battery for cordless phones By LEO SIMPSON Do you have a cordless phone in your home? Isn’t it annoying when you have a blackout and you can’t use your phone? This little project is about adding a backup battery to the base station so that it keeps going regardless of blackouts. 16  Silicon iliconCChip hip Y OU KNOW the situation. You come home in the evening and the meal is on the stove cooking and then the lights go out. You start scrabbling around for a torch or candles and then you can look up the phone number for the local electricity authority. Next problem: your cordless phone is not working and the regular handset is in another room or doesn’t work or you gave it to your sister. So there you are, in the dark, no power and without a phone! Sure the handheld phone has its own battery but the base station doesn’t, so when the mains power goes, so does the phone. This situation has occurred in the author’s house on several occasions recently and I decided to do something about the phone – I wish I could do something about the blackouts but that’s another story. So what can you use for a backup battery? My older Telstra Freedom 400 cordless phone used a 12V plugpack and so the obvious answer was to use a 12V SLA (sealed lead acid) battery as the backup. The circuit would be real simple, involving just a diode and a resistor, as shown in Fig.1. But most cordless phones on the market now seem to use any voltage but 12V. For example, the Telstra Freedom 320 cordless phone pictured uses a 9V plugpack while Panasonic models use 13.5V. Other brands use 6V or 8V or you name it. Not to be deterred, I sat down and nutted out the circuit of Fig.2. It is more complicated than Fig.1 but it has the advan­tage that it can be tailored to suit almost any cordless phone/ plugpack combination possible. It uses an LM317T adjustable 3-terminal regulator and by changing just one or two resistors, you can make it suit your particular situation. The catch is that you won’t be able to use your existing plugpack if it puts out less than 14V. Most 12V DC plugpacks easily exceed 14V and can deliver quite a lot more, depending on the load current. Now let’s have a think about the required voltage and cur­ rent for a typical cordless phone base station. While they may all come with a DC plugpack which is labelled 6V, 9V, 12V or whatever, the actual voltage delivered is usually about 15% more, depending on the mains voltage itself. For example, the Freedom 320 comes with a 9V plugpack but it voltage close to 10.5V, depending on circuit tolerances. If you want other voltages, the table on the circuit shows the required values for R1 and R2. The 0.1µF capacitor at the input to the LM317 and the 10µF capacitor at its output are included to ensure stability. Fig.1: use this circuit if your cordless phone base station runs at 12V. You will be able to use your existing 12V plugpack to charge the 12V battery and power the phone. When the power goes down, the 12V battery will keep the phone powered up. Construction We built the prototype onto a small piece of Veroboard, as pictured, but we have also designed a small PC board to do the job and its component overlay is shown in Fig.3. Fig.5 shows you need to install it and the battery inside a suitable plastic case. We used a 12V 2.3A.h battery available from Oatley Electronics and we installed it in a standard plastic utility case measuring 197 x 63 x 102mm. This is just the right length for the selected battery. A smaller battery would enable you to use a smaller case but then its backup time would be shorter. We mounted a DC socket, to suit the connector of the 12V plugpack, at one end of the case and a 4-way terminal block for the output and battery terminations, at the other end. The bat­tery itself was secured in the case with nothing more than a few short lengths Parts List Fig.2: this circuit uses an LM317T regulator to produce 10.5V to power a 9V cordless phone base station. When the power goes down, the 12V battery keeps the base station still powered at 10.5V. We use 10.5V instead of 9V because that is typically what the 9V plugpack would deliver. delivers around 10.5V and the load current is typically around 80mA, regardless of whether the unit is recharging the phone battery, on a call or just sitting there waiting for something to happen. Since the cordless phone is likely to have more range and more noisefree operation at 10.5V than at the nominal 9V, it makes sense to have the backup supply produce a similarly higher voltage. So for the 6V case, you would design for an operating voltage of about 7V and so on. Referring back to the circuit of Fig.2, the power from the 12V DC plugpack is fed to the input side of the LM317 3-terminal regulator and to the 12V battery via a 100Ω resistor which has a diode, D1, connected across it. The 100Ω resistor allows a trick­le charge current of about 10mA or so into the battery while ever the power is applied. When the power goes off, the battery then supplies the 3-terminal regulator via diode D1. The output voltage of the 3-terminal regulator is set by the three resistors connected to its Adjust terminal. The values shown will give an output a component layout using Veroboard and while it may not be the simplest possible, it does have the advantage that no tracks need to be cut. Assembling the PC board is straightforward. Just remember to put the diode and 10µF capacitor in the right way. If you decide to use a piece of Veroboard make you sure wire the LM317 in the right way and note that it does have a rather odd pinout, as shown on the circuit of Fig.2. Once the circuit board is assembled 1 12VDC plugpack 1 panel-mounting DC socket to suit plugpack 1 DC female power line plug to suit cordless phone base station 1 12V SLA battery (see text) 1 PC board, 33 x 25mm, code 12510991 1 plastic utility case, 197 x 63 x 102mm 1 4-way insulated terminal block 1 LM317T adjustable 3-terminal regulator 1 1N4001 diode 1 22µF 16VW electrolytic capacitor 1 0.1µF MKT polyester capacitor Resistors (1%, 0.25W) 1 56kΩ 1 2.2kΩ 1 270Ω Note: for other voltages, see table on Fig.2. Fig.3 (left): this small PC board accommodates all the components. Make sure you put the LM317T in the right way around. Fig.4 (below) shows the actual size artwork for the PC board. October 1999  17 This view inside the plastic case shows the 12V SLA battery and the small circuit board (in this case, the Veroboard version) which accommodates the LM317T adjustable 3-terminal regulator. Fig.5: trickier to assemble, this Veroboard layout will do the same job as the PC board version shown in Fig.3. of double-sided foam adhesive tape. The battery can be expect to last for many years so it probably will never need to be removed. Connect two wires from the DC socket to the appropriate points on the circuit board and apply power. Check that the output of the circuit is 10.5V DC or whatever your required voltage is. Remember that if the voltage is a little higher or lower than you expect, say 10.7V instead 10.5V, it does not matter. The phone will still work happily. After the various wires were at18  Silicon Chip The Veroboard version will save you the expense of a PC board. tached to it, the cir­ cuit board was itself attached to the base of the case, again with a length of double-sided foam adhesive tape. Complete all the wiring inside the case and then make up an output lead with a DC connector on it to suit the DC socket on your cordless phone base station. It is most important that you get the exact type to fit. If you get the wrong type it may not fit at all or it may be such a sloppy fit that its operation will subsequently be unreliable. Testing When all the wiring is complete, connect the DC plugpack to the case and the DC output to the cordless phone base station and check that it all operates as it should. Check that the battery takes over when the DC plugpack is disconnected. Finally, check that all functions of the phone work exactly as they did when powered directly by the original DC plugpack. Finally, here’s another thought: the same system could be used as a battery backup system for a phone answering machine. That way, if you have a blackout, you will not miss out SC on any phone messages. NEW SUPER LOW PRICE + LASER AUTOMATIC LASER LIGHT SHOW KIT: MKIII. Automatically changes every 5 - 60 secs. Countless great displays from single to multiple flowers, collapsing circles, rotating single and multiple ellipses, stars, etc. Easy mirror alignment with “Allen Key”. Kit inc. PCB, all on board components, three small DC motors, mirrors, precision adjustable mirror mounts: (K115) + very bright 650nM laser (LM2) module. Kit with laser module $60 Kit + laser module + plug-pack + instument style case all at a special price of $75 12V Automotive Relays with 30A SPDT Contacts (73 ohm relay coil). RRP $7. our price $4 ea. 4 for $12 ***NEW***WHITE LED 5mm 3500mcd. Very bright Ideal for mini torch etc.... $4 ***NEW*** 35-140 LED IRILLUMINATOR KIT Comes on in the dark or can be controlled by alarm system. Kit includes mount ing tray & universal swivel mount.35 LEDs $29. Extra 35 LED pack (3extra packs max) $16 per pack. 140 LEDkit:$67 Ideal for use with our B/W cameras to see in the dark. KEY-CHAIN LASER POINTER in a presentation box. Quality metal housing + 3X LR44 /AG13 bats. FREE. Extra bats. 50c Ea. $60 ***SUPER SPECIAL*** Oatley Electronics Shop Open Fridays 1pm-4:30pm & Saturdays 10am4pm during Sep. & Oct. as a trial. On sale will be surplus & special sale B R A N D N E W PA C K A R D B E L L items only. All regular advertised, catalogue stock & kits must be ordered in KEYBOARDS. Top quality Packard Bell advance by Phone, Fax or E-mail & can be paid for & picked up at the shop. computer keyboards for just $12 Ea. 200A RADIO CONTROL MODEL SPEED CONTROL KIT This kit is designed to work direct from a STD 1-2ms pulse from a R/C receiver to control an electric motor (in one direction only). Kit includes PCB + all on-board components inc. 5 high power MOS-FETs, a wiring kit and fuse holder & 26 x 64 x 38mm case. Features include brake. Don’t pay $150 for commercially available one Coming soon for less than $35 < $35 September Sale. To see just what’s on sale just check out the September Sale link on our new web page or if you have a polling fax you can see our text list of sale items on 02 95707910. But don’t forget our web page BARGAIN CORNER where we sell all of our regular specials like run out end of stock & special one or few of items like A portable medical X-Ray machine for $1500. OVER $100,000 WORTH OF OFFICE SUPPLIES FOR ABOUT 1/4 OF RETAIL. Folders, binders, directory boards + lettering, cork boards, white boards large & small, fabric boards, bulletin boards, notice boards, instant signs, desk signs, flip charts + easels and more, Mostly quality Quartet brand products. Sale to be held on our web site 14 Oct. & at a location to be announced on 15 &16 Oct. in the Peakhurst / Mortdale area. Do your company / school a favour & tell your Purchasing Officer NOW!!! PELTIER EFFECT DEVICES. Could be used for cooling overclocked PC CPUs. All 40 X 40mm. 4A T 65deg. Qmax 42W $25 6A T 65deg. Qmax 60W $27.50 8A T 65deg. Qmax 75W $30 Comes with info to build cooler / heater plus data. Some used heatsinks avail. NEW MOSFET STEPPER DRIVER This kit is designed to work below 5V & Line lens+$0.80...X-hair lens greater than 35V (higher voltage +$0.80...Module (no case) only $8 MOSFETS avail.)Very efficient (very little heat) & work with software like DANCAD 16 X 2 LINE LCD CHARACTER etc.(for step/dir-ection signals) & is ideal for CNC projects. It works well with the DISPLAY stepper motors in our + 1M IDC famous German ext. cable, printer $45 or$35 LED, buzzer & switch on $12 or 3 for $30 with new or previous printer purchase a PCB. NEW...PC MOTHERBOARD TWO MOTOR LASER LIGHTSHOW KIT UMC-486 CACHE ISA SX 40Mhz. Inc. motors, mirrors, reversing switch & all Original package, 486-40Mhz CPU, book electronic components. Can be controlled inc..., 5 X 16 bit & 1 X 8 bit slots, 4 X 30 pin by variable DC input. Lots of patterns, & 1 X 72 pin Mem. slots 220 X 170mm $18 flowers, stars etc. $16 Laser module $8 GET YOURS BEFORE THEY ALL GO USED AUSSIE MADE TRANSFORMER BUILD YOUR OWN COMPUTER CONTROLLED 2/3 AXIS MACHINE 240V PRIMARY (120+120),ES screen, Secondary....1X12V<at>1.1A...10V<at>5A...7 using parts of our now famous $46 surplus V<at> 5A... 12-0-12V<at>7.5A. 100 X 115 X GERMAN PRINTER & CNC shareware (DANCAD) The printer is full of steppers, 100mm. bargain at $15 NEW FULLY FEATURED ANSWERING toothed belts, pulleys, bearings etc (EA MACHINES.Brand new in original box with June 99). we have plans/notes for $9 (on manual, tape, plug pack and phone lead floppy) & links to find lots of info on the net . (NEW) 12V / 2.3Ah AUDIOVOX LEAD Call screening, up to ACID BATTERY (Model BTR-1900). 2.5 min. out going Priced at a fraction of their real value (as message, VOX recording, used in video cameras & older mobile power fail protection, phones - same as Panasonic batteries we memo record, sold before). 180 (L) x 60 (H) x 22 (W) mm, plays music 0.67Kg, made in Japan. The contacts before (easily soldered) are at one end of the beep, battery. 2 batteries digital + suitable volume control, programable security 500mA code, remote call breakthrough, room float monitor, full re-mote features, save charger. messages, AUSTEL approved. Bargain 8 CHANNEL IR REMOTE CONTROL priced to clear at $25 KIT: Uses a Magnavox remote control box & 8 keys, & replace the existing Tx PCB. TOLL FREE PHONE NUMBER The RX uses an IR RX module <at> 38KHz. Sorry but we don’t have one but if The output of this simply feeds the you call 02-95843564 24hrs & matching SM5032B decoding IC. There leave a message & your number are 8 outputs, 2 toggl-ing & 6 momentary. To convert the TTL outputs to drive a relay. we will call you back ASAP at our (K65D) Dual Relay Kit below. Transmitter cost. (ORDERS ONLY) PCB: 89 x 30mm. RX PCB: 48 x 34mm: Tx Kit (K65T) $20 Rx Kit: (K65R) $20 VOLUME CONTROL KIT: With the above ACN 068 740 081 Tx and Rx kits you can add a motorised PO Box 89 Oatley NSW 2223 pot. / volume control to anything (K65V) Ph ( 02 ) 9584 3563 Fax 9584 3561 $16 This kit can also be purchased with the orders by e-mail: oatley<at>world.net above two kits, an RCA & suitable www.oatleyelectronics.com Plugpack: (K65C) $55 major cards with ph. & fax orders, DUAL RELAYS KIT: With the above Tx & Rx kits you can control 2 relays to be momPost & Pack typically $6 Prices subject to change without notice entary or latching: (K65D) $8 $29 $10 $25 $20 OATLEY ELECTRONICS S O L A R PA N E L S A R E B A C K Quality SEIMENS brand Polycrystalline cells. Voc Isc 1W output. 4 panels req. to charge 12V batteries. Specifications: Open circuit voltage: 5.7v...Short circuit current: 0.22A Peak Power: 1.0W <at> 100mW/ sq cm... Dimensions: 160mm x 55mm x 5mm...Flying lead: Dual cable 25cm long. Should be placed under glass for outdoor use.$10ea. or 4 for $36 MASTHEAD AMPLIFIER KIT SPECIAL The MAR-6 available separately $4. The amplifier gives good results with any two metal wires or strips acting for the antenna. It should even work with a coathanger! Basic kit with both the PCBs & all on-board parts (K03) $15 ...Basic Kit + 2 Weather-proof Plastic Boxes + plug-pack: $24 (ask for your free case with this item) NEW AUSTRALIAN PLUG PACKS AT BELOW WHOLESALE PRICES GENERAL ELECTRIC 20VA 14VDC <at> 700mA..... AUDIOVOX 9V <at> 500mA AUDIOVOX 12V <at> 400mA.... $5 Ea. or 5 for $20 XENON FLASH TUBES Removed from disposable cameras. Just add a AA cel. STROBE KIT also available. uses above flash$6 $3 Ea. or 4 for $10 - battery not included + MODEM MADNESS Why buy a fast modem when it is rare to log on at the maximum speed. We have 28.8 modems that come with a free Approved. CD rom / 9Vac plug free 30 hour pack required. internet connection (not supplied) CFL INVERTER KIT our very popular inverter. The improved design uses a larger transformer and a SG3525 switch Mode Chip.This very Efficient Driver kit can drive a number of CFL’s from 12vdc. & would be great for lighting the weekender or caravan Kit inc. 1 inverter & 1 CFL: $35 Extra CFLs $13 $25 *** FANTASTIC BARGAIN *** COMPUTER POWER SUPPLY PCB: New PCB assembly. Dimensions are 45 x 108 x 200mm. Switchable 120/230V AC input. DC outputs are +5V<at> 6A,+ 12V <at> 1A,-12V<at>1A,-5V<at>1A. Data Inc.RU approval. Mains input . Be Quick: (Ps6) . 4 for $24 ***NEW*** PANAFLOW brand 60mm 12VDC FANS. $3 Ea OR 4 FOR $10 coming soon PRO PIC MICRO PROGRAMER User up to 39 different types of PIC chips, Works under DOS, WIN 3.xx & WIN 95, Quick Easy construction, Connects to Pc’s parallel port. Download fully functional evaluation software from the Internet register for a small fee. More details on our web page BASIC PIC MICRO PROGRAMER JUST Learn program your own 16F83 /16F84 /16C84 micro-controllers the easy way with this simple kit that just plugs in to your Pc’s . Kit inc. program examples and notes PCBs, all on-board components, Db25 connector & a PIC chip ready to program. Software available free to Download From our web page $27 $32 UHF AUDIO / VIDEO TRANSMITTER KIT Kit includes all components needed...... PCB plus all on-board components, connectors, switch, metal case, telescopic antenna, twin RCA A/V lead, all that is needed to complete the full kit. 12Vdc <at>10mA operation. Ideal for transmitting audio and video around you suitable home.. Complete plugcack $5 Kit for just $28 AT LAST! A COLOUR CMOS CAMERA WITH GOOD RESOLUTION + BUILT IN AUDIO + FREE PLUG PACK + F R E E V H F M O D U L AT O R . Available with swivel mount or dome mount housing. $160 No Audio $160 BNC connector (video), DC connector (power), RCA connector (audio). 330000 pixel. 330 TV line res. 7-12Vdc 55mA max. INTRO PRICE $160 ** CCD CAMERA SPECIAL ** WITH A FREE VHF MODULATOR The best "value for money" CCD camera on the market! 0.1 lux, High IR response & hi-res. Better than most cheaper models. 32 X 32mm $105... With 1of these lenses pinhole (60deg.), 92 deg.; 120 deg. or for (150 deg) add $10 20-30 SECOND SOUND / VOICE RECORDER KIT. This kit could be used as an message machine at your door or as a personal reminder device & is easy to assemble. Gives good quality sound at 25 sec, Uses LS I chip with memory etc. all built in. Kit includes PCB, all on-board components, electret microphone, switches & small surplus speaker. $19 $19 SC_OCT_99 SERVICEMAN'S LOG Did lightning strike at all? The old saying that “lightning doesn’t strike twice in the same place” has a new twist these days. Did it strike at all? Many insurance claims for lightning strikes on TV sets are best described as dubious; and they can put the serviceman in the hot seat. Mr Lancia (not his real name) had already sought service elsewhere for his Toshiba 2529SH, 21 System, 63cm stereo TV receiver. It had been purchased overseas but I only found this out later. When he brought it in, he said that it had died as the result of a lightning strike and could I prepare an estimate for insurance? Estimates are tricky things and are best avoided in other than exceptional circumstances. The only way one can “estimate” is to actually fix the set. But by doing that, the estimate concept disappears; it now becomes a factual situation. Material costs have been incurred and hours of labour have been spent. The estimate becomes the final account. And if the customer doesn’t like it, what then? The best that I could hope for in this current situation would be that a lightning strike might produce enough visual evidence to support a rough guess as to the minimum cost. But there is no way of knowing whether the obvious damage is covering a host of additional “invisible” problems. In any case, if an insurance claim is involved, it’s necessary to first determine the validity of the lightning strike theory before going any further. This set was probably made for the Middle East market and certainly not for Australia. I tried to order a service manual from the Toshiba agent, only to be told that they had never even heard of this model, far less have any parts for it. They were pretty emphatic that there would be no support available in Australia for this set. I was on my own. I removed the covers and made a visual check. Significant­ly, I was unable to see any signs of lightning damage. Encouraged by this, I switched on; there was no sound or picture but it was far from dead. First, I could switch the power indicator LED from “Standby” to “ON” from the remote Fig.1: this circuit section from a Toshiba 3418DA helped solve the problem with a Toshiba 2529SH, which isn’t sold locally. It shows the TA8783N jungle IC and, in particular, the Vcc pins (6, 40, 61 and 63). 20  Silicon Chip control, as well as from the front panel controls. Also, there was 124V on the collector of the horizontal output transistor (Q404) and the horizontal drive transistor (Q4022). But there was no voltage anywhere on the 64-pin jungle IC (IC501, TA­ 8783N). I wasn’t familiar with this device but it ap­peared that pin 39 was the horizontal drive output and that the crystal on pin 37 was part of an oscillator. I couldn’t work out much more without a circuit and I especially needed to find out which was the supply rail pin (Vcc). Next, I went to the power supply and measured the rails on the output from the chopper, Most had voltages but it was far too complex to work out what was what. I did notice that a relay on the primary was switched off by a link across the base emitter of its driver transistor. When I removed this link the relay began to chatter loudly. Once again, without a circuit diagram, it was too hard to find out how it was meant to work, so I refitted the link. This was about as far as I could go and the set was put aside. I told the client the situation and he liaised with his insurance company, presumably with a view to writing the set off. Lateral thinking Months later, I was fixing another Toshiba for a different problem and I needed technical assistance from the local Toshiba agent. They weren’t able to help directly, suggesting instead that I try one of their larger agents in Melbourne. I telephoned them and they were able to help with my immediate problem. Buoyed by this, I thought I’d push my luck and asked if they had heard of a 2529SH model. They hadn’t but, as an after­thought, I asked them if they had any Toshiba circuitry using the TA8783N IC. The technician offered to a look and after a minute or two he came back and said he had a circuit for a 3418DA which used this IC and that I could buy a copy if I wished. I agreed to go ahead and when the circuit arrived I found that two Vcc rails are fed to this IC: 9V on pin 40 and 12V on pins 6, 63 & 61. I took a punt on pin 40 and traced this back to the power supply before the trail went cold. The power supply was completely different from the 3418DA circuit and the only chance I had now was to trace out the circuit. This was a fairly ambi­tious approach; it was very complicated with about 20 transistors and it was going to take some time. I had already established that the 12V rail was derived from the horizontal output transformer via a 3-pin IC regulator. This regulator is designated as a UPC2412HF but I am unfamiliar with it. However, I was still following the idea that the 9V supply to pin 40 was critical. Two issues now had to be resolved before I spent more time on this theory: (1) was the set worth fixing?; and (2) was I going to get paid for it? To answer the first point, I hooked up an external 9V power supply and switched it and the TV set on together. This produced both sound and picture and everything looked fine. This confirmed that the fault was confined to the 9V source – apart from the previously mentioned relay. I revisited this part of the circuit briefly and found that when the set was on, the relay was silent – it was only in the standby mode that it chattered. I also worked out that its func­tion was to short out two large, low value resistors which limit­ed the 240VAC supply to the main bridge rectifier. Finding out how all this worked and fixing the problem was going to be time consuming. I phoned Mr Lancia, and he said he was quite prepared to pay for all my efforts if I could do it for less than $300. He already had a new set from the insurance company and he could use this set as a second set if I could fix it. So in the next month or so, whenever I had some spare time, I would draw the circuit of the power supply module. The result was four voltage sources: 124V, 8V, 16V & 17V, all of which were present and correct. The 17V rail fed an NPN transistor (Q870) which generated 9V at its emitter, the 9V supply then going to pin 40 of IC501. However, there was no 9V on the emitter of Q870. The transistor driving Q870 was another NPN transistor, designated Q871. Its base was controlled by a network of transis­tors and other assorted devices. When I shorted Q871’s base and emitter leads, its the collector voltage rose and turned on Q870, restoring both picture and sound. I was on the right track at last. Safety circuit But it was still complicated; the network of transistors controlling the base of Q871 was also part of the remote control on/off power circuit, including the safety cutoff. I already knew that the remote system was working properly, which left the safety circuit to investigate. From what I could work out, it involved an SCR (D859), which was controlled by the horizontal output stage via a series of small unidentified glass diodes from the 8V rail to the 16V rail. I tried disconnecting various parts of this circuit, one at a time, to see whether the set would fire up. Items Covered This Month •  Toshiba 2529SH TV Set •  JVC 775AU TV Set •  JVC CX-60ME TV Set •  Hitachi C33-P900 TV set •  Mac LC630 computer And it wasn’t until I disconnected these diodes, which I realised were unidentifiable zeners (D890, D891, D892 & D893) that the circuit finally fired up. Because I couldn’t identify the diodes, I decided to recon­nect them and measure the voltage across each one. Believe it or not, when I did this, the set continued working and nothing I could do would recreate the fault. I froze them and heated them but they wouldn’t fail. I assume that, in the process of unsol­dering them, the fault had somehow been fixed. Regretfully, the circuit involving the relay was in the too hard basket. I tried to draw the circuit but it used over 10 transistors, plus optocouplers, in all sorts of bizarre configu­rations. I can only guess it was some sort of current sensor safety circuit but I couldn’t work it out, so I left it as I found it. I left the set on soak test for couple of weeks before calling Mr Lancia. I quizzed him on this and other parts of the fault which I really couldn’t attribute to lightning. Finally, it emerged that he had the same faults before and that someone else had done the same sort of thing as I had, which kept it going until the recent storm. So, was the storm really involved? I don’t know. Nor did he explain why he hadn’t returned the set to the previous repairers, nor did he say who they were. For my money he was really a rather October 1999  21 dodgy sort of bloke – but at least I was paid for all the work I did. Two elderly JVCs Two elderly JVC TV sets came into the workshop this week – one a 51cm model and the other a 15cm battery/ mains portable. Both were over 10 years old and belonged to different customers, and both sets were dead. The 51cm unit was a 7755AU, while the baby was a CX-60ME with an attachable mains power supply. Some­what surprisingly, their circuit diagrams were similar, with both employing an AN5900 pulse width modulator IC for the low voltage supplies. I started with the baby, which I found would still work with a 12.5V bench power supply. I opened up the AC adaptor (AA-60ME) and what was left of resistors R09 and R10 told the story. Fortunately, having the circuit for both sets was a bonus. The two resistors were in the emitter circuit of the power output transistor Q03 (2SD­1453), which turned out to be short circuit. I replaced these and applied power. There were no fire­works; in fact there was nothing – the unit was dead. Transistor Q03 takes its collector voltage from the bridge rectifier, D01, via the 22  Silicon Chip primary of transformer T03. And the collector was sitting at 340VDC; the unloaded voltage from the bridge and the mains. Nothing was oscillating and it is a little obscure as to exactly how the circuit worked. However, I figured out that the problem was in the starter circuit Q01, Q02 & Q05. The ohmmeter indicated that Q01 had a base-emitter short but the others were OK. This circuit supplies the start-up voltage to start IC01 oscillating until the secondary 12V takes over. I fixed this and the whole power supply started working but was producing a fierce whistling sound. This implied that it wasn’t oscillating properly, probably due to a leaky electrolytic capacitor. There were about 10 of these and I started to hang addi­tional capacitors across the most likely ones until I reached C22. Replacing this, a 47µF 16V unit, finally stabilised the circuit and it behaved properly, giving a 12.5V output. I had already soldered any potential dry joints and I left it on soak test. Moving on to the larger set, there were no low tension voltages at all from the power supply and a relay was not acti­vating. I checked the voltage at the emitter of Q03, which is fed directly from the bridge rectifier and there was no 11V as indi­cated on the circuit. Nor was there any voltage on Q03’s collec­tor, test point TP98, out of bridge rectifier D11, or even from the power transformer T02. It wasn’t until I removed T02 that I found that its primary winding was open circuit. This didn’t look good but I persevered. I fitted an external bench power supply across the bridge rectifier and ran it up to 62.5V, as indicated on the circuit. This produced low voltage rails of -28V, +12V and + 5V, the latter derived via IC001 (LA7930). But the 110V main HT rail was low and causing trouble in another part of the power supply. This turned out to be due to horizontal output transistor Q551 (2SD1453), which was short circuit. I thought that replacing this would be the end of the story but worse was to come. While I now had sound, there was no pic­ture and there were blue sparks inside the picture tube. All the indications were that the picture tube was down to air and this was subsequently confirmed. It was a good job I hadn’t ordered a new T02 transformer, because the sick picture tube was the death knell for this set. There was no way one could justify the cost of a new tube (assuming one could be found) and the labour costs involved. It was a write-off. That’ll teach me to muck about with sets over 10 years old! The big Hitachi Mrs Belrose asked me to service her 78cm Hitachi C33-P900 (G8P chassis) TV set at home because the prospect of bringing it back to the workshop was horrendous. She complained of obscure intermittent faults such as intermittent loss of picture, intermittent flickering and a monochrome picture for three minutes or so when cold. These faults hardly ever occurred when the set was warm, although occasionally it would flicker for few seconds when switching from the AV (audio/visual) sockets to the tuner. I removed the back of the set and looked around. I was looking for the AGC control and the associated circuits when I happened to see one of several small black electrolytic capaci­ tors on the video board. It had literally spat the dummy – or, more correctly, the electrolyte – all over the PC board. Then I saw another, and another, and realised all 30 or so electrolytics were leaking badly. Most, if not all, would to have to be replaced. It was a big job, and one that couldn’t be done in the customer’s home. Though the set looked a lot younger, I learned from the service manual that it was 10 years old. But apart from these problems, the picture on the 78cm picture tube was still good which meant that the set was worth fixing. After all, a replace­ment would cost $1500 or more. I wasn’t looking forward to taking the set back to the shop. However, I managed to round up three helpers and it wasn’t too bad for the four of us, considering the set’s dimensions and weight (80 x 72 x 57cm and 64kg). I started by replacing all the electro­ lytics, mostly 10µF, on the video signal board, hoping that would fix most of the problems. It didn’t. I then examined the small electrolytics on all the other boards. Two of these, C918 (1µF 50V) and C950 (470µF 60V), were particularly bad but I also changed a few other low-value units which might be causing hum on the power supply rails. Altogether, I replaced 40 electrolytic capacitors, cleaned up all the corrosive electrolyte from them and felt confident that I had cracked it – but I hadn’t! The thought of replacing every last one of the remaining capacitors was too much to con­template. It was time to get technical. The main clue I had was that it was temperature sensitive so, using the hair­dryer and freezer, I followed the video rails from the tuner as they branched out all over the set. Being a multi-system set, it was fairly complex to follow. During this procedure, I followed a few false trails, espe­cially at pin 8 of IC501, which I noticed earlier had hum on it when connected to the oscilloscope. I had also used a signal source plugged into the AV input sockets and noticed that the stronger the signal, the less chance there was of the symptoms occurring. For example, the set was much better in the AV mode and SBS (the strongest signal in this area) was better than all the other channels. Anyway, after messing around for a long time around IC501, I found I wasn’t really progressing and continued until I reached IC701 (TDA­ 2579A), which is the jungle IC. There I noticed that freezing it caused the horizontal frequency to change (I could hear it) and then the picture vanished. I gradually isolated the area down to the components adjacent to pin 6, especially C619 (2.2µF 50V). Replacing this capacitor removed all the remaining symptoms. The easy bit was over – all I had to do now was manhandle the set back to Mrs Belrose! Secondhand Mac Our local school was given some secondhand Macintosh com­ puters but one, an LC630, had died, so it was brought in to me to see what I could do. I hadn’t worked on these before and the first problem was figuring out how to get inside the unit. It was like a Chinese puzzle. This meshed with that and that slid into this, to unlock something else, and so on. However, after a lot of time, I even­tually managed to locate and remove the power supply. Eventually, I managed to unscrew the final metal screening can and remove it. But, in so doing, my hands touched a part of the PC board and even though the set had been switched off for hours, I received an awful shock. I instinctively let go if it and the wretched device tumbled to the floor. After I had recovered with a very stiff cup of coffee, I carefully picked up the module and examined it closely. Fortu­ nately, it hadn’t been damaged by the fall and the incident had given me a major clue. It was obvious that I had received the shock from the fully charged filter capacitor following the mains bridge rectifier which meant that no current was being drawn from it. This in turn suggested that the power supply wasn’t oscillating. So the first step was to find the start-up circuit. That wasn’t too difficult. I soon found two 220kΩ resistors in series (R16 & R17), one of which had gone high. Replacing them (after shorting out the remaining charge on the main electroly­ tic) completely fixed the power supply. The only remaining prob­lem I had was trying to remember how everything went back togeth­er again. I charged for two hours labour and the bill came to $114. I was worried the school might think that this was too expensive, especially as one can buy complete PC power supplies for less than $60. However, the school was delighted as they had been quoted SC over $200 for a replacement! October 1999  23 BUILD THE RAILPOWER A remote controlled throttle for model railways Do you have a model railway layout? Does your speed con­troller have remote control, simulated inertia and facilities for auxiliary outputs? If you said “no” to any of those questions, then have a look at this completely new design which incorporates all the wanted features from previous versions of our highly success­ful Railpower speed controller. PART 1: By JOHN CLARKE & LEO SIMPSON 24  Silicon Chip O VER THE YEARS SILICON CHIP has produced some notable model railway circuits with perhaps the most popular of all time being the Railpower Walk­ around Throttle published in the April & May 1988 issues. Since then, we have produced a version with infrared remote control in 1992 and a microprocessor-based version in 1995 but none of the later versions was as popular with model railway enthusiasts. And while the original Walkaround Throttle was a good design in its time, it’s now 11 years old and lacking a lot of features that enthusiasts now want. About six months ago we decided to review our previous circuits and come up with a completely new design. The new cir­cuit would obviously incorporate all the good features of the original design but would have things like LED indicators to show all the various modes. Each time you press a That’s right – there are no front panel controls on the Railpower; just eight indicator LEDs and a speed meter. All control inputs come from the handpiece which has buttons for Stop, Inertia, Forward, Reverse and Speed, plus two more button to switch a couple of auxiliary outputs. button on the rem­ote, something lights up on the control panel. So what were the good features of our original design? They include pulse power for very smooth and reliable loco opera­tion, motor backEMF monitoring for excellent speed regulation even at crawling speeds and simulated inertia (momentum) so that the model loco acts as though it is pulling the hundreds of tonnes of a real train. As well, there was the very desirable feature of full over­load protection including a buzzer and LED indicator to show the fault condition. After all, nothing is more annoying than having your model train come to an abrupt stop for no apparent reason. If you have inadvertently placed a short across the rails or the loco was derailed when crossing points, the Rail­power Walkaround Throttle gave an immediate indication of the fault condition. OK, OK, if the Walkaround Throttle was a brilliant design, what were its drawbacks? The most apparent, and one which applies to virtually all model railway controllers, is that it was possi­ble to throw the loco into reverse while it was barrelling along in the forward direction. This is highly undesirable, for two reasons. First, it is not very realistic, is it? If a real train went straight from forward into reverse (or vice versa) without slowing down, all the passengers would end up in a pile at the ends of the carriages with multiple fractures, swearing and lawsuits! Second and more important for railway modellers, the loco and carriages usually derail and all the rolling stock can end up on the floor, which also can cause breakages and swearing! The way around this problem is to prevent the circuit from throwing the loco into reverse while ever there is voltage pres­ent across the track. This requires some logic so that even if you inadvertently press a button to change the direction of the train, the circuit won’t do anything unless the train has come to a full stop. Another problem involved the simulated inertia. While this provides a very realistic effect in enabling the train to gradu­ally build up speed, it can be a problem when you are doing shunting. That’s easily fixed though; the remote has a button to switch the inertia feature on or off. No more buzzing And finally, there was the buzzing. With the original Wal­karound Throttle, locos often buzzed while they were stationary. Why was that? All model locomotives require a few volts DC (sometimes as much as 6V) before they will even start moving, so the circuit features a “minimum” setting so that the loco moves off immediately when you increase the track voltage slightly by winding up the throttle knob. But because the track voltage from our circuit is pulse width modulated, October 1999  25 Main Features •  Pulse output for smooth low speed operation. •  Back-EMF detection for excellent speed regulation. •  Full remote control of all operating features. •  Speed setting displayed on a meter. •  Simulated inertia can be switched on or off. •  Forward/Reverse lockout to prevent derailment. •  Over-current protection with audible and visible indicators. •  LED indicators for forward, reverse, stop, reverse lockout, inertia and track voltage. the very narrow pulses fed to the loco while it was stationary would often cause the motor to buzz. Sometimes they would also cause the loco to creep forward imperceptibly too, which could be a bad thing when it was supposed to be sitting at the lights waiting for the “all-clear” signal! This problem has been solved in this latest version, so that if you press the Stop button on the remote control, not only does the loco come to a complete stop but the track voltage is completely removed. Result: no buzzing, no creeping. Remote control We’ve already mentioned the Inertia and Stop buttons on the remote control. But there are seven buttons in all. There are two buttons to switch two auxiliary outputs on or off and another two buttons select forward or reverse operation. Finally, there is an elongated button to speed up or slow down the locomo­tive. The Railpower itself is housed in a plastic instrument case with nine LEDs on the front panel, a power on/ off switch and a small analog meter to indicate the speed setting. At the back of the case are a pair of terminals for the track connections, another pair of terminals for the 12VDC output and an access hole for the wiring to the auxiliary outputs. Inside the Railpower case is a large 26  Silicon Chip PC board which takes up most of the available space. All the LED indicators are along the front edge of the board while the four power transistors and power supply components are near the back edge. The components are well spread out to make construction as easy as possible. There are six trimpots provided to set the following: maxi­mum track voltage, minimum track voltage, inertia, braking, meter calibration and the forward/reverse lockout adjustment. The maximum track voltage (VR1) is usually set to the rated voltage for the particular locomotive, typically 12V. The minimum track voltage (VR2) is set to just below the threshold before the loco begins to move. This setting will be a compromise to suit most of the locos used on your layout. The inertia adjustment (VR4) determines the time the train takes to accelerate to its set speed, as indicated by the analog meter on the front panel. Typically, the time taken to reach maximum speed can be adjusted from about five seconds to about one minute. If you have a large layout and run long trains you will want the long inertia setting and conversely, if you have a small layout and run short trains, then you will want the small inertia setting. By way of explanation, inertia also affects the braking of the train. So if you have a large inertia setting the train will take a long time to stop, if you just wind the throttle setting down. The Stop trimpot (VR5) has its own inertia setting and can bring the train to a halt more quickly. The adjustment range is from about 10 seconds down to half a second. VR3 is the Lockout adjustment, to set the track voltage speed at which the forward/reverse buttons can be used. You can set between 0V and about 2.5V. VR6 sets the full-scale reading on the speed meter. This is simply set so that the meter reads 100% when the train speed is set at maximum. Its adjustment is made after the maximum and minimum speed settings have been finalised. Block diagram & circuit The block diagram for the Railpower is shown in Fig.1. The infrared receiver (IC1, IC2) decodes all the commands from the handheld remote. Depending on which button is pressed, one of IC2’s outputs goes high to drive a particular section of the circuit. The full Railpower circuit is shown in Fig.2. It requires three different supply rails. The infrared receiver circuit needs 5V while most of the rest of the circuit runs from 12V so quite a few transistors are required to shift from the 5V output of IC2 to the 12V levels of the rest of the circuit. IC1 & IC2 are supplied with 5V from regulator REG1. IC1 is a 3-pin infrared receiver which incorporates a filter centred on 38kHz and a de­modulator to recover the digital coding pulses produced by the infrared transmitter. Its output at pin 1 is inverted by transistor Q1 and then fed to pin 2 of IC2, the decoder chip. The 39kΩ resistor and .001µF capacitor at pin 13 set the oscillator so that it matches the transmitter. IC2 has toggle outputs and momentary outputs. The momentary outputs are high only while the respective transmitter buttons are pressed. The toggle outputs alternate between high and low, each time their respective buttons are pressed. We use the toggle outputs to control the Aux1 output (pin 10) of the Railpower and the Inertia on/off feature (pin 9). Hence, if the Inertia button is pressed once, the Inertia can be turned on and the next press will turn it off. Similarly, one button press turns the Aux1 output high and the next press turns it off. All the other outputs are momentary and are high only while the respective transmitter pushbuttons are pressed. As noted above, trimpots VR1 and VR2 set the maximum and minimum track voltage. Op amp IC3a buffers VR1 while IC4a buffers VR2 and these buffered voltage sources are used to set the range of track voltages which are stored in capacitor C1, depending on how the speed button is pressed. Op amp IC4a is actually set up as a voltage clamp so that C1’s voltage cannot go below the setting of VR2. If C1’s voltage goes above the setting of VR2, as it will when the speed setting is increased, diode D2 becomes reverse biased and therefore has no effect on the capacitor voltage. So let’s look at how the speed setting is increased or decreased, when the speed button on the remote is pressed. When pin 6 (Speed+) of IC2 goes high Fig.1: the block diagram for the Railpower. The infrared receiver (IC1, IC2) decodes all the commands from the handheld remote control unit. Depending on which button is pressed, one of IC2’s outputs goes high to drive a particular section of the circuit. it turns on transistor Q2 and this pulls pin 9 of analog switch IC5a low, turning it on. This causes C1 to charge via the 10MΩ resistor towards the +12V supply rail. Ultimately, C1’s voltage is limited by D1 which will conduct to clamp the voltage according to the setting of VR1. Thus C1 is limited to the voltage set by VR1 plus the forward voltage of D1. When pin 6 of IC2 goes low, Q2 turns off and switch IC5a goes open circuit, leaving C1 to sit at the previously stored voltage. When pin 5 (Speed-) of IC2 goes high, it turns on transis­tor Q3 which discharges capacitor C1 via a 4.7MΩ resistor. Note that C1 is prevented from totally discharging by the clamping action of IC4a and diode D2, as described above. Some readers may be wondering why we used such a complicat­ ed system to charge and discharge C1. Couldn’t we have simply charged and discharged C1 via high value resistors from the wipers of trimpots VR1 & VR2? The answer lies in how a capacitor charges up via a resistance. Initially, the capacitor charges at quite a fast rate but when the voltage reaches about 2/3rds of its final value, it takes much longer to complete the charge. The response is exponential. In practice, this means that C1’s voltage would be very slow to rise above the medium to fast settings and be similarly slow when going from a slow setting to stop. If we charge and dis­charge capacitor C1 from the full supply rail and clamp the voltage at around 1/3rd and 2/3rds the supply, then we are charg­ing and discharging over a more linear range. Thus the speed buttons have a much better response, particularly at the very slow and fast speeds. Capacitor C1 is buffered with FET-input op amp IC4b. Its very high input impedance means that it has virtually no effect on C1’s voltage. The 1kΩ resistor in series with pin 5 probably looks unnecessary in view of the high circuit impedance but is included to prevent any chance of spurious oscillation. IC4b drives the analog meter via VR6 and charges the iner­tia capacitor C2 via the inertia trimpot VR4, the 10kΩ resistor and analog switch IC5c. Switch IC5c is arranged as a single pole double-throw (change-over) type, so that its pin 14 connects to pin 12 or pin 13, depending on the state of its control pin 11. Stop function Pin 11 is controlled by pin 1 of IC6a, a 4013 D-type flip­flop. When pin 1 of IC6a is high, it causes pins 13 & 14 of IC5c to connect together which conFig.2 (following page): it controls the speed of the locomotives by applying a variable pulse width modulation (PWM) waveform (from pin 7 of IC8b) to a H-bridge transistor output stage (Q15-Q22). October 1999  27 28  Silicon Chip October 1999  29 instead will force the circuit to be in reverse mode at power up. Pulse width modulation The H-bridge transistors (Q16, Q17, Q20 & Q21) are all mounted on the rear panel, which provides the necessary heatsinking. nects the Stop trimpot, VR5, across capacitor C2. C2 then discharges so that the train comes to a stop. At the same time, pin 1 of IC6a turns on transistor Q13 which powers the LED4, Stop indicator. Pin 1 of IC6a is toggled low or high at each positive tran­sition of the clock input at pin 3, as driven by IC7c and tran­sistor Q5. So each time the Stop output from pin 7 of IC2 goes momentarily high, IC6a is clocked and it selects or deselects the Stop function via switch IC5c. Flipflop IC6a is also controlled by the speed (+) or speed (-) outputs of IC2, ie, pins 5 & 6. If either of these outputs go high, diode D3 or D4 will conduct, turning on transistors Q6 & Q7 which pulls the reset at pin 4 of IC6a high. This sets the Q output (pin 1 of IC6a) low, to release the stop function. Inertia on/off Pin 9 of IC2 controls the inertia function and as mentioned above, it is a toggle output and it drives transistor Q4. When pin 9 is high (Inertia Off), Q4 is on, pulling the control pin 10 of switch IC5b low, closing the switch; ie, pin 2 of IC5b con­nects to pin 15. This shorts the inertia trimpot, VR4, and this means that C2 charges and discharges almost instantaneously in response to speed changes. At the same time, LED3 lights to indicate that Inertia is off. Comparators IC3c and IC3d monitor the voltage across ca­pacitor C2. Pin 14, the output of IC3c, goes low whenever the voltage across C2 is above the voltage set by the Forward/Reverse 30  Silicon Chip Lockout trimpot, VR3. Pin 14 going low causes both diodes D5 & D6 to conduct which prevents the forward and reverse outputs, pins 3 & 8 of IC2, from having any effect. Buzz off Comparator IC3d prevents the locos from buzzing when they are stationary, as mentioned above. Its non-inverting input, pin 10, monitors the voltage between IC3a and IC3b’s outputs via a voltage divider comprising a 100kΩ resistor and a 1kΩ resistor. This voltage is only slightly higher than the minimum track voltage setting provided by trimpot VR2 (ie, buffered by IC3b). So when the voltage across C2 is below pin 10 of IC3d, pin 8 goes high, pulling up pin 6 of NAND gate IC7d. If the Stop function is also activated, then IC7d’s pin 4 will go low and prevent the pulse width modulation circuit from working. We’ll come back to that section later. Forward & reverse So what happens when the lockout comparator and diodes D5 & D6 are not inhibiting the forward/reverse outputs from IC2? When pin 8 is momentarily high to select Forward operation, Q11 is turned on and this sets flipflop IC6b via gate IC7b. This causes pin 13 of IC6b (the Q output) to go high and pin 12 to go low. IC6b controls the direction of the motor drive circuit, as we will see later on. The 0.1µF capacitor at pins 8 & 9 of IC7b will force the circuit to be in the forward mode when the power is applied to the circuit. Placing the 0.1µF capacitor at pins 12 & 13 of IC7a As mentioned previously, the Rail­ power provides pulse drive to the track, using a system called pulse width modulation. This is widely used these days in switching power supplies and refers to the fact that the average DC voltage is varied by varying the width of pulses applied to the load or in this case, the railway track. However, while switching power supplies use pulse width modulation to obtain high efficiency, in the Rail­power we use it not so much for efficiency (although that is an advantage) but to obtain very smooth and reliable low speed running from the loco­motives. Part of the reliable running comes about because the pulse vol­tage applied to the loco’s motor is considerably higher than if DC was applied. For example, in the Railpower the pulse amplitude is around 16V or so, regardless of the average voltage applied to the track. Consider how this affects starting and low speed running. Normally, with a conventional train controller, if you want to run the loco at low speed, you must use a low track voltage and you increase the throttle setting gradually to make the smoothest possible starts. The problem is that model loco motors don’t necessarily respond well to low track voltages. The slightest bit of friction in the gears, a bit of dirt on the track or less than perfect contact between brushes and commutator can mean that the loco does not start smoothly or it may not start at all. Or perhaps the track voltage needs to be wound up to quite a high level at which point the loco suddenly lurches forward – hardly the most realis­tic model operation. With the Railpower however, the track voltage is always high (ie, 16V) and we just vary the pulse width to vary the amount of power fed to the loco. Result: much more reliable starting and really realistic low speed running, even with long trains, double-headed locomotives and dirty track and so on. After using a conventional train controller, the Railpower is a revelation! The pulse width modulation (PWM) circuit comprises op amps IC8a, IC8b, Most of the parts are mounted on a single large PC board, so that the Railpower is a snap to build. We’ll give the full wiring details in next month’s issue. the comparator from delivering pulses to the motor drive circuit. IC8c and IC8d, all in one LM324 quad op amp package. IC8d is connected as an oscillator and it produces a triangular (sawtooth) waveform by alternately charging and discharging a 0.1µF capacitor via a 560kΩ resistor. Capacitor C2 (the inertia capacitor) is buffered with op amp IC8a which is connected as a unity gain non-inverting stage. Its variable DC output is fed to pin 5 of IC8b via diode D9. IC8b is connected as a comparator, comparing the triangle waveform at its pin 6 with the DC voltage at pin 5. Whenever the triangle waveform at pin 6 goes below the DC at pin 5, IC8b’s output at pin 7 goes high and conversely, whenever the triangle waveform at pin 6 goes above the DC at pin 5, the output at pin 7 goes low. The result is a pulse waveform running at about 160Hz and with a duty cycle which is directly proportional to the DC vol­tage at pin 5. If the DC voltage at pin 5 is high, the duty cycle H-bridge motor drive of the pulse waveform will be high and the average DC output will be high also, say 9V or higher. The operation of the pulse width modulation circuit is shown in the oscilloscope waveforms of Fig.3. The upper trace is the pulse output waveform at pin 7 of IC8b. This has a nominal 10% duty cycle, giving an average DC track voltage of about 1.7V, assuming that the supply is 17V. The lower trace is the triangle waveform at pin 13 of IC8d and the horizontal line (Ref1) is the DC voltage at pin 5 of IC8b. If the voltage at pin 5 rises then the pulse width at pin 7 of IC8b increases to provide more track voltage. As noted previously, when the train is brought to a stop with the speed down control, the track voltage pulses will be very narrow and while the loco may stop, its motor may buzz. However, if the Stop button is pressed, IC7d’s output will go low and pull pin 5 of IC8b low via diode D10 and this stops The motor drive circuit uses four Darlington transis­ t ors (Q16, Q17, Q20 & Q21) connected in an H-bridge configura­ tion. The beauty of this circuit is that it can drive the motor in the forward or reverse directions, depending on which two diagonally opposite transistors are turned on. For example, to make the motor go forward, Q21 is turned on continuously, while Q16 is pulsed on and off at 160Hz. Conversely, to make the motor go in reverse, Q20 is switched on continuously, while Q17 is pulsed on and off. Tran­sistors Q15 & Q18 ensure that Darlington transistors Q16 & Q17 turn on hard so that their power dissipation is minimal. They also provide voltage translation from the 12V logic control signals from IC9a and IC9c to the +17V supply for Q16 & Q17. Q19 & Q22 ensure that their respective Darlingtons turn on fully, again to October 1999  31 Fig.3: these waveforms show the operation of the PWM circuit. The top trace is the pulse output waveform at pin 7 of IC8b, the lower trace is the triangle waveform at pin 13 of IC8d and the horizontal line is the DC voltage at pin 5 of IC8b. If the voltage at pin 5 rises, then the pulse width at pin 7 of IC8b increases to provide more track voltage. ensure that their power dissipation is minimal. As we noted previously, flipflop IC6b controls the H-bridge circuit and thus the direction of the motor. For forward motor operation, the Q output, pin 13, of IC6b is high and the Q-bar output, pin 12, is low. So pin 13 switches on transistors Q22 & Q21. Meanwhile the pulse waveform from IC8b drives pin 1 of the 3-input NAND gate IC9a and thence Q15 & Q16. For reverse operation, the Q output of IC6b is low and Q-bar is high. Thus IC9a’s output will not follow the pulse wave­form at its pin 1, since its pin 2 is low. But pin 13 of IC9c is now high, being connected to the Q-bar output of IC6b. So the pulsed waveform from IC8b passes through to drive Q18 & Q17. And Q19 & Q20 are switched on by the Q-bar output of IC6b. The forward and reverse modes are indicated by LEDs 6 & 7 which are driven by the Q-bar output of IC6b, AND gate IC9b and transistor Q25. When the Q-bar output from IC6b goes high, Q25 switches on and LED6 is powered via the 1.2kΩ resistor, to in­dicate the reverse mode. When IC6b changes state for the forward mode, Q25 is turned off and LED7 can turn on via diode D13. Overload protection The Railpower incorporates overload protection so that if the loco stalls while crossing points or a short is placed across the track, the current is limited to a safe value. What happens 32  Silicon Chip Fig.4: how the motor back-EMF is monitored. The top trace is the track voltage applied to the motor and the back-EMF is the wavy line between the pulses. The lower trace is the voltage fed to op amp IC8c. Note how the back-EMF is shorted out by Q14 during the period that the pulses are applied to the track. is that the motor current flows through the emitter of Q20 or Q21 and then via a common 0.1Ω resistor which is used to monitor the pulse current supplied to the track. The voltage developed across the 0.1Ω resistor is filtered with a 10kΩ resistor and 0.1µF capacitor and fed to the base of transistor Q23. If the averaged track current exceeds more than about 5 or 6A, Q23 will turn on and pull pins 8 & 11 of IC9 low. This causes the outputs of IC9a and IC9c to stay low and stops any pulse drive to the H-bridge. Q23 also lights overload LED8 and switches on the buzzer via transistor Q24. Q24 also pulls the positive side of the 22µF capacitor connected to Q23’s base high which main­tains base drive while the capacitor charges. With the track current shut down to zero and the 22µF ca­pacitor at Q23’s base fully charged, Q23 & Q24 turn off. Gates IC9a or IC9c then reapply What About A Walk-Around Throttle Version? For those who want to build the Rail­ power without infrared remote control, it is possible to build a walk-around throttle version with a small handheld control which you can plug into sockets at various points around your layout. The modifications are quite simple and involve omitting IC1 and IC2 on the Railpower PC board. Depending on available space, we hope to publish the details next month or in December. switching pulses to their respective transistors to power up the track again and the 22µF capacitor discharges via the buzzer. However, if the overload condition has not been fixed, Q23 & Q24 will turn on again and repeat the cycle. In effect, the circuit keeps “looking” to see if the fault has been removed and the buzzer keeps sounding at about one-second intervals. Speed regulation One of the outstanding features of the Railpower is its speed regulation and this contributes to smooth and reliable running at any speed setting. The circuit accomplishes this by moni­ toring the back-EMF from the motor. Model locomotives mostly use permanent magnet motors and these produce a back-EMF which is directly proportional to their speed. So this circuit monitors the motor back-EMF and varies the pulse drive to ensure that the back-EMF is maintained more or less constant for a given speed setting. This ensures that the loco does not slow down when going up an incline and also enables much more realistic shunting manoeuvres. The trick is, how do you measure motor back-EMF while power is applied to it? The answer is that we measure the back-EMF in the time between the individual track pulses, using two 10kΩ resistors, one connected to each rail. Depending on whether the loco is going forward or backwards, the back-EMF comes from only one rail and the respective 10kΩ Parts List For RailPower Controller 1 PC board, code 09310991, 216 x 170mm 1 front panel label, 246 x 75mm 1 remote control label, 28 x 62mm 1 plastic instrument case, 260 x 190 x 80mm 1 8-channel infrared remote control transmitter & receiver (from Oatley Electronics) 1 60VA 24V centre-tapped or 2 x 12V transformer (see text) 1 MU45 1mA panel meter 1 mini buzzer 1 SPST mains rocker switch with Neon indicator (S1) 1 IEC mains cord 1 IEC mains panel socket with 1A fuse 1 IEC insulating boot 1 red binding post terminal 1 black binding post terminal 2 white binding post terminals 5 TO-220 mica washers or silicone insulating washers 5 TO-220 insulating bushes 2 eyelet terminals for earth connection 1 3mm star washer 5 self-tapping screws for PC board 8 M3 x 15mm screws and nuts 2 M4 x 10mm screws and nuts 2 4mm flat washers 3 10mm OD 5mm ID rubber grommets 4 cable ties 15 PC stakes 1 400mm length of brown 250VAC wire 1 200mm length of blue 250VAC wire resistor feeds this voltage via D11 to pin 3 of IC8c, the error amplifier. Note that Q14 is turned on when ever a pulse is fed to the track and this shorts out the voltage signal from the respective 10kΩ monitoring resistor. Hence, op amp IC8c never “sees” the track voltage pulses and we effectively monitor the motor back-EMF only while no voltage is applied to it. The oscilloscope waveforms of Fig.4 shows how the motor back-EMF is monitored. The top trace is the actual track voltage applied to the motor. The back-EMF is the wavy line between the pulses. The lower trace is the voltage fed to op amp IC8c. Note how the back-EMF is shorted out by Q14 during the period that the pulses are 1 200mm length of green/yellow 250VAC wire 1 250mm length of blue heavy duty wire 1 200mm length of red heavy duty wire 1 75mm length of black heavy duty wire 1 75mm length of yellow light duty hookup wire 1 75mm length of red light duty hookup wire 1 30mm length of black 20mm diameter heatshrink tubing 1 30mm length of black 5mm diameter heatshrink tubing Semiconductors 1 PIC12043 infrared receiver (IC1) (Oatley Electronics) 1 SM5032B 8-channel decoder (IC2) (Oatley Electronics) 2 LM324 quad op amps (IC3,IC8) 1 TL072, LF353 dual JFET op amp (IC4) 1 4053 CMOS analog switch (IC5) 1 4013 dual D flipflop (IC6) 1 4093 quad 2-input NAND gate (IC7) 1 4073 triple 3-input AND gate (IC9) 1 75L05 5V low power regulator (REG1) 1 7812 12V regulator (REG2) 1 BC548 NPN transistor (Q1) 17 BC338 NPN transistors (Q2Q6, Q8-Q11, Q13-Q15, Q18, Q19, Q22, Q23,Q25) 3 BC328 PNP transistors (Q7,Q12,Q24) applied to the track. Back to the error amplifier: this has a gain of 3.2 and it amplifiers the chunks of motor back-EMF and filters them with the 22kΩ resistor and 2.2µF capacitor at its output. The resulting smoothed DC voltage is used to shift the output of the triangle waveform generator, IC8d. If the back-EMF from the motor is lower than it should be, the DC level of triangle waveform will be lowered. When applied to pin 6 of IC8b, the PWM comparator, this will have the same effect as if the DC fed to its pin 5 was raised. The result is a slightly wider pulse width fed to the track, to restore the motor speed to what it should be. 2 BD650 PNP transistors (Q16,Q17) 2 BD649 NPN transistors (Q20, Q21) 11 1N914, 1N4148 switching diodes (D1-D6,D9-D13) 3 1N4004 1A diodes (D7,D8,D14) 8 5mm red LEDs (LED1-LED8) 1 bicolour 5mm LED (LED9) Capacitors 2 2200µF 25V PC electrolytic 1 100µF 16VW PC electrolytic 1 47µF RBLL electrolytic (C2) 1 22µF 16VW PC electrolytic 8 10µF 25VW PC electrolytic 1 2.2µF RBLL or tantalum electrolytic (C1) 1 2.2µF 16VW PC electrolytic 2 0.1µF MKT polyester 1 .01µF MKT polyester 1.001µF MKT polyester Resistors (0.25W, 1%) 1 10MΩ 5% 3 22kΩ 1 4.7MΩ 5% 36 10kΩ 1 560kΩ 1 4.7kΩ 1 220kΩ 2 3.3kΩ 1 120kΩ 3 2.2kΩ 8 100kΩ 7 1.2kΩ 1 47kΩ 6 1kΩ 1 39kΩ 1 0.1Ω 5W Trimpots 1 1MΩ (105) horizontal (VR4) 1 220kΩ (224) horizontal (VR5) 2 100kΩ (104) horizontal (VR1, VR2) 1 10kΩ (103) horizontal (VR3) 1 5kΩ (502) horizontal (VR6) Turning now to the power supply, the Railpower uses a 60VA power transformer which may be either a centre-tapped 24V unit or one with two separate 12V windings. The transformer with two 12V windings is connected to a bridge rectifier using four diodes, while the centre-tapped 24V transformer can drive a full wave rectifier using two diodes. The rectified AC is filtered with two 2200µF capacitors to supply about 17V DC to the H-bridge circuit. A 7812 3-terminal regulator (REG2) provides 12V for the remainder of the circuit. That’s all we have space for this month. Next month, we will describe the transmitter circuit and give the full SC constructional details. October 1999  33 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.altronics.com.au Introducing Just imagine it: two tonnes of rhino is charging straight at you, the ground beneath you trembling violently. Somehow you survive the onslaught but you can still hear him, menacingly, just behind you. Or maybe you’re right alongside the Concorde as it screams down the runway, struggling to take off. But you’re not just watching or just listening. You’re feeling the thrust of those mighty Rolls Royce engines. No, you’re not on safari in the wilds of Africa. You’re not even in New York, let alone the middle of JFK International. You’re relaxing in the comfort of your own home. And you’re experiencing Home Theatre! FEATURE BY LOUIS CHALLIS October 1999  37 Pioneer's Advanced Home Theatre setup includes the SDT50W1 16:9 50-inch TV, VSA-E06/VSX-D906S remote controlled 5-channel home theatre amplifier; DVL-919E DVD/VCD/LD/CD deck, F204 synthsizer Tuner, CTw606DR double casstte deck, PD-F957 CD Carousel. . . plus SHF10, main speakers and S-W200 powered subwoofer. H ome Theatre? What is it? What does it mean? This is far removed from watching a rented VHS movie It means you can have the excitement of on your small-screen TV set. This is Home Theatre! action movies in your own home, complete So what do you have to buy to get started and what with magnificent surround sound and large screen, might you have to spend to get a fully blown home high definition picture and best of all, you can have it theatre system? Do you have to spend a fortune to anytime, night or day, as often as you want... start or can you work your way up to it? Why is it that new film releases create so much exTo get the low-down on this story, we’ll hand over to citement at your local cinema? Louis Challis*... Mostly it is the big screen with its much larger than life images which gives the story such impact. That lunging crocodile is so much more terrifying when it is much larger than life on that big screen. Combine the visual impact with a full range multi-channel audio system that surrounds you with sound and you have an experience which is well worth paying ten or fifteen dollars – you just can’t get the same impact by renting the same movie from your local video store! Or at least, you couldn’t until very recently. Now you can! But is that really true? A full blown cinema in your own home with large screen and full range sound? Yep. Take that movie everyone knows well: “Jurassic Park”. In that first scene the puddles of Onkyo's DC-S717 water tremble when the Tyrannosaurus Rex is DVD/CD/Video CD on the move. With Home Theatre, you can feel player (top) and TXthat tremor right through your seat. It’s not loud DS747 Dolby Digital but you can feel it. receiver is a complete home theatre system Or take an action movie such as “True Lies” control centre with where you have the sights and sounds of helaround 730W from 5.1 channels . Some idea of the input/ icopters and jet-fighters coming from every output complexity of modern home theatre equipment can be direction; you can have the same realism as gained from the rear panel of the TX-DS939 receiver above. in your local big-screen cinema. 38  Silicon Chip Feature by Louis Challis  At the end of 1998, I was in the USA and one of the shops I visited had more than 3000 DVD (Digital Video Disc) titles on its shelves. With that sheer volume of software available, it’s not hard to see why the Americans have has embraced home theatre in a big way. In Australia, things have been moving a lot more slowly but now they are accelerating rapidly. . . At this point, relatively few readers will have experienced the aural and visual excitement that quality home theatre can provide. It can be just as good as your first visit to a surround-sound cinema featuring one of the action-packed blockbuster movies. Now while a home theatre setup might not give quite the same visual impact as your local cinema’s wide screen, it can probably do a much more impressive job as far as the sound reproduction is concerned. With quality multi-channel sound reproduction, the sound system will more than make up for the difference in screen size. And if your budget can stretch to a video projection set-up or large plasma screen you can have the best of both worlds: a large dramatic screen and an really impressive sound system. Jamo's 2B system with DCM-10B controller with remote, DCM-5 and DCM-6 front speakers, DCM-4 centre speaker and DCM-8 subwoofer. Software & hardware Ultimately, the quality of your home theatre system is of little interest if you don’t have appropriate software. While there are thousands of movies available for sale or hire for VHS VCRs, that’s a second-best option. DVD, Digital Video Disc, is the way to go as the picture quality is far better than from even the best domestic VCR. Currently, there are over 300 DVD movie titles available for sale or hire in Australia. By Christmas that figure will be more than 1000 and building fast. As far as DVD players are concerned, the world has been divided into six different zones, for marketing, copyright and distribution reasons. North America is Zone 1, while Australia, New Zealand and Oceania are Zone 4. Replay of most software is deliberately restricted to players for that intended zone and so Zone 1 software will not normally play on a Zone 4 player. In order to gain access to a wider range of DVD titles, some people have gone as far as to obtain a Zone 1 player (or have even obtained a player specially modified to play multi-region discs) and then have imported Zone 1 discs but there is trap in this approach. A Zone 1 disc played on a Zone 1 (or multi-region) DVD player will produce an NTSC (American) standard video signal whereas a Zone 4 disc played on a Zone 4 DVD player will produce a PAL video signal. This presents no problems if your TV set, video monitor or projection set can handle both NTSC and PAL signals. But if you have an older PAL-only TV set, an NTSC video signal will probably not be viewable or if it is, you may see it only in black and white. This is not quite the effect you are seeking... All this partly explains why DVD Zone 4 software has been slow to become available in Australia. Such DVD discs have to go through the complete mastering process before they can be mass-produced and there has been quite a steep learning curve in Australia to make this possible. S The B&W Nautilus 800 series from Convoy International includes this HTM2 speaker with the special tweeter which is a feature of the Nautilus range. The shape of things to come - except they're already here. Philips FLATTV is a full-function plasma screen TV set which hangs like a picture on the wall, just 11cm deep. ctober 1999  39 OOCTOBER By the way, there are some DVD players which will play an NTSC disc on a PAL TV at full resolution by doing an internal NTSC/PAL conversion (Samsung's DVD907, for example). The picture standard of DVD will immediately change your attitude to your faithful VCR. In brief, once you’ve seen DVD programs you won’t want to go back to VCR tapes. Not only has the quality of the video signal been enhanced by DVD (with its 625 line PAL format), but more significantly, most pre-recorded DVDs offer 5.1 channels of audio supplemented by the option of 2-channel composite audio. Before we go any further, what do we mean by ‘5.1 audio channels’? Five of the nominal six audio channels on any Dolby Digital system are the front left, right and centre channels and the rear left and right channels. The sixth channel is the ‘sub-woofer’ channel which covers a very limited range of frequencies between 10Hz and about 150Hz. Because its effective bandwidth is only about one-tenth that of the other five channels, it was initially described as being the ‘point-one’ (0.1) channel, and that name stuck. Three types of DVD players are currently being sold in Australia. In the first category are the DVD ROM players that come with the latest generation of Pentium and PowerMac computers, or are available as an add-on. The peripheral hardware integrated into or supplied with these computers generally limit the number of audio channels to two. However, there are some nifty sound systems being marketed which provide a surround sound field which is impressive nonetheless. Ultimately though, a computer-based DVD player cannot match the performance of a multi-channel DVD player with its dedicated 5.1 channels of sound. The second type are the more basic and less expensive units, currently the most widely sold DVD players. These provide two direct composite audio channel outputs (Left and Right) that are suitable for feeding directly into your * Introducing Louis Challis SILICON CHIP is delighted to announce that the renowned audio consultant and hifi reviewer Louis Challis has joined our editorial team. As well as being an eminent audio consultant who has worked on projects as diverse as Australia’s Parliament House, the Pedestrian Crossing System for the Blind and the FA18 Fighter test booth, Louis Challis has a long record as a hifi reviewer, starting with “Australian Hifi” magazine in the late 1970s and continuing with “Electronics Today International” and “Electronics Australia”. Now Louis is writing for SILICON CHIP – you'll see his authoritative and interesting hi fi articles in the magazine from time to time. 40  Silicon Chip existing 2-channel stereo hi-fi or TV system. All basic DVD players also incorporate a supplementary digital MPEG Audio/PCM output socket. Provided you have a separate Dolby Digital/Pro Logic Processor, then you can utilise the full 5.1 channels of encoded audio output on your DVD. Should you choose to buy a basic DVD player, you’ll need a 5-channel amplifier with integral Dolby Digital decoder or a Dolby Digital decoder to provide those 5.1 channels of sound. Alternatively, you could buy a DVD player that incorporates its own Dolby Digital decoder. This will provide the six (5.1) audio channels outputs to be fed to the associated amplifiers and loudspeakers. The third type are the DVD players incorporating the full Dolby Digital decoding circuitry. These typically cost approximately $400 to $500 more than their more basic counterparts. However, if you look closely at the specifications for these costlier units, you will generally find that they provide more features and slightly better performance. Ultimately, the choice between the three options will be dictated more by financial considerations than by published specifications. If it’s home theatre you want, then you are ultimately restricted to the last two options. Home theatre amplification The cost of DVD players is invariably less than that of a good 5-channel amplifier. Most good 5-channel amplifiers have power outputs between 60 and 120W in the three (front) main channels, and the same or lesser power output capability in the rear channels. Most of these amplifiers incorporate an AM/FM tuner, various digital sound processing options, plus Dolby ProLogic and other decoding options such as DTS. Of course many readers already own a reasonably large stereo amplifier rated between 60 and 200W and will want to use that in their home theatre system. Some manufacturers, notably Yamaha with its DSP-E492, have recognised the need, and are marketing a three channel amplifier to supplement your existing quality stereo amplifier. The Yamaha DSP-E492 amplifier’s single (main) volume potentiometer will then control all six channels. Home theatre speakers If you’ve spent heaps on your DVD player and 5-channel amplifier, then you should be prepared to spend a similar amount of money on your six sets of speakers (ie, for your five conventional channels and your sub-woofer). If you already have a pair of quality stereo speakers, then you can retain them and then buy a quality centre speaker, two good rear speakers and perhaps a self-powered sub-woofer. The most critical speakers in the system are the left and right front main speakers. However, don’t be fooled, the centre speaker similarly plays an extremely important role, and far more so than most people realise. When selecting your centre speaker, its quality (and specifically the balance of its frequency response) should closely match that of the main left and right speakers. If it doesn’t, then speech reproduction can be distinctly odd. Your rear speakers, although normally less important than the front speakers, still have an important role to play in achieving a multi-directional sound field. In other words, don’t be tempted to buy too cheaply here. There are two types of loudspeakers currently being offered for the rear channels: the conventional ‘mono-pole’ speakers, in which the acoustical output is single-sided, and the less conventional ‘dipole’ speakers in which the acoustical output is projected from both the front and rear faces. Dipole speakers are recommended by Lucas THX and when correctly selected and placed, are generally capable of providing a more uniform and diffuse sound field. Sub-woofers Two basic types of powered sub-woofers are available. The first and generally less expensive group have been designed to provide ‘maximum bang’ when reproducing the explosive sounds contained within many action-movie soundtracks. These speakers usually provide a ‘peaky’ frequency response that is most effective over a limited frequency range of 40Hz to 80 or 90Hz. While they can perform reasonably well on movie sound tracks, they are not so good on music. By contrast, better quality (and frequently more expensive) sub-woofers provide a smoother frequency response typically covering from 20 or 25Hz to beyond 110Hz, with a maximum non-linearity of ±3dB across the band. The good point about any subwoofer is that since low frequency sounds are non-directional, the subwoofer can be placed anywhere in your home theatre space. They can be placed out of sight, behind a sofa, even under a table, anywhere you like. Video monitors and projection systems Although we’ve left the subject of screens till last, it is the most exciting aspect of home theatre and the choice is very wide. In the first category of choice are the conventional video monitors which range up to 80cm in conventional 4:3 screens and around 76cm in widescreen (16:9) sets. Funnily enough, because of their wide theatre-aspect ratio, these wide-screen models don’t look as big as equivalent conventional sets. For bigger and better impact though, you can’t go past a projection TV. The picture quality is not as sharp or as bright as conventional picture tube sets but the large screen can give the same ‘larger than life’ impact as the screen in your local cinema. By way of example, the latest Sony VPL-X1000M delivers a dazzling 1100 ANSI lumens of light output and works happily with conventional video, SXGA (1280 x 1024 pixels) and happily up-converts or down-converts the input signals to optimise the SVGA panel’s capabilities. Not everybody wants a projection TV, though and even with 1100 lumens of output, you should still have a darkened room to achieve the optimum visual/optical contrast. The ultimate display? Perhaps the ultimate is “a picture on the wall” without the bulk or complexity of rear projection or even the bulk of a TV set. Such a flat display can be achieved with TFT LCD displays, but in relatively small sizes. That’s not home theatre though, so obviously we have to look further. As I discovered at the Winter CES in Las Vegas, the answer has arrived with at least eight manufacturers offering 42 inch plasma displays. The most exciting plasma display was Pioneer’s magnificent 50 inch display which earned copious ‘oohs!’ and ‘ahhs!’ from the diverse crowd of journalists and marketing personnel attending the show. The advantage of a plasma display is that it can be just hung or placed on the wall, just like a picture. The display is typically 75mm thick and unlike many other large screen systems, can be viewed in a brightly or normally illuminated room. The display is not subject to magnetic distortion and, with appropriate line doubling, offers a picture whose resolution and quality is second to none. As you may appreciate, that sort of performance costs a lot. Don’t lose heart though, as the cost must ultimately drop and my preferred choice (and ultimately yours) will be a plasma display. The developments in home video are truly exciting. The pace of development is accelerating rapidly and we will see a huge range of equipment and software released over the next year or two. At the time of writing, two of the major DVD software distributors in Australia have announced that they intend to simultaneously release the DVD versions of their software with the VHS video tapes to video shops. Given the choice of hiring a DVD instead of a VHS tape, which one would you select? Do you want dazzling pictures, in 4:3 and 16:9 format and with full surround sound? I know which one I would go for . . . SC DVD is the only choice! October 1999  41 NOW EVEN BETTER! Even 42  Silicon Chip LOWER cost Internet access IT'S AS EASY AS A-B-C TO GET CONNECTED! (a) Fill in this form and either post it or fax it to SILICON CHIP – (02) 9979 6503; or (b) Call SILICON CHIP on (02) 9979 5644; 9am-4pm Mon-Fri and we'll guide you through it! (c) WE WILL THEN FAX YOU OR POST YOU your password and EASY setup details. 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If you prepay for three months you avoid paying the setup fee of $10.00 One Month ($10.00 SETUP FEE APPLIES) Three Months (NO SETUP FEE) ❏ Low Vol: $10 + $10 setup fee (5hrs then $2.00/hr) ❏ Low Vol: $30 no setup fee (15hrs then $2.00/hr) ❏ Regular: $20 + $10 setup fee (10hrs then $1.80/hr) ❏ Regular: $60 no setup fee (30hrs then $1.80/hr) ❏ Power: $49.95 + $10 setup fee (25hrs then $1.60/hr) ❏ Power: $149.85 no setup fee (75hrs then $1.60/hr) Note: charges are made on a calendar month basis. When do you wish to start:  straight away  beginning of next month Choose your email address (user name of 2-8 letters), eg, yourname<at>silchip.com.au First Choice:__________________Second Choice:___________________Third Choice:___________________ Choose your Dial-In Location (also known as POP - Point of Presence) from this list: ❏ Sydney (inc outer metro)   ❏ Newcastle   ❏ Wollongong   ❏ Gosford, Windsor, Wiseman's Ferry   ❏ Penrith, Mulgoa, Camden   ❏ Campbelltown, Helensburgh   ❏ Melbourne (inc outer metro)   ❏ Geelong   ❏ Cranbourne, Mornington   ❏ Healesville, Emerald, Pakenham   ❏ Gisborne, Romsey, Kilmore, Kinglake   ❏ Lara, Balliang, Bacchus Marsh  ❏ Brisbane (inc outer metro)   ❏ Gold Coast   ❏ Perth   ❏ Adelaide   ❏ Hobart   ❏ Canberra (Note: Some locations within these areas may be community or STD calls. Please check with your telephone service provider if in any doubt) Initial charges (Credit card charged ONLY after password & setup information have been forwarded): Monthly/3-monthly plan charge: $________ Plus setup fee: $10.00 (if applicable) $ _______ = Total: $ __________ October 1999  43 MAILBAG More coal burning power stations to come I am writing with reference to your publishers letter in the July 1999 edition, entitled “Collie’s New Coal-Burning Power Station”. If only your statement in the opening paragraph were true – “When all of the current issues are concerned, it should be the last of its kind.” Unfortunately for our side of the industry, it is not true and by a long margin at that. I refer you to a number of new coal-fired power generation investments that have, or are about to be committed: (1) Callide C: 840MW black coal in Queensland – under construc­tion; (2) Millmerran: 840MW black coal – Surat Basin Queensland – just granted a generation authority by the state government; (3) Kogan Creek: 840MW black coal – Surat Basin Queensland – undertaking Environmental Impact Study (or equivalent) at the moment. There are another two power stations of similar size also under development – Wondoan and Tarong expansion. Collie at 300MW is relatively insignificant compared to the above. What is worse is that $1 billion in new transmission in­vestments in each of Queensland and NSW is planned over the next five years. The Australian Cogeneration Association (ACA) has serious concerns regarding the proposed investments, specifically that Australia’s commitments to limit the growth of greenhouse gas emissions under the Kyoto protocol will not be met. If built, the Millmerran plant will emit over 6 million tonnes of carbon dioxide per annum. When added to the greenhouse gas emissions of the Callide C power station now under construc­tion, these two developments alone will burden Australia with 12 million tonnes of greenhouse gas emissions per annum. This will increase significantly the adjustment burden on the Australian community to meet agreed emissions reduction targets. The Government cannot hope to develop a credible greenhouse gas strategy if subsidised coal-powered 44  Silicon Chip power stations continue to be built. This is of particular concern because the need for electricity generating capacity can be met by a combination of cogeneration plants, gas-fired power stations and renewable sources having substantially lower CO2 emissions. Ric Brazzale, Executive Director, Aust. Cogeneration Association. Data strobing in FM radio tuner In the June 1999 issue of SILICON CHIP magazine, your FM Radio Tuner project erroneously describes the ISA bus IOR signal as that which is involved in strobing data into your tuner card. In fact, it should be the IOW (I/O Write) signal that is used for this purpose. My IBM AT Technical Reference has this to say: ‘-I/O Read’ instructs an I/O device to drive its data onto the data bus. It may be driven by the system microprocessor or DMA controller or by a microprocessor or DMA controller resident on the I/O chan­nel. ‘-I/O Write’ instructs an I/O device to read the data on the data bus. It may be driven by any microprocessor or DMA con­troller in the system. Franc Zabkar (via email). Bigger power transistor packages needed I have been involved in electronics since the inception of the semiconductor transistor and that means the germanium series, not just the silicon series. Being a bit of a power fanatic my passions lie in the solar industry area but speed control and other electronic species are not exactly out of my bounds. My first introduction to power transistors goes back to the OC16, a germanium PNP power transistor. The transistor case was unique and used copper as the entire encapsulation. The mounting method was a single bolt of around 8mm diameter with the base and emitter leads exiting through the centre of the bolt. After that came the two most common cases that reigned for quite a long period, the TO-3 and the TO-36. The TO-3 was probably the most popular and probably the bane of most users and technicians as the mounting, wiring and insulating was most tedious. The leads were never long enough for the thicker heatsinks and insulating the leads from the heatsink without letting the solder run down the leads was an art in itself. The TO-36 was a little better as the leads were longer and there was only one bolt, which came with the device along with its nut, but generally these packages were more expensive. If one is to look in the back of a D.A.T.A. power semicon­ductor data book one can see the myriad of different styles of power packages that have been invented over the years. Some of these packages like the M-1205 for instance are a much better design than the TO-3. The M-1205 is a direct inversion where the leads exit on the other side of the case making it sit all inside the instrument case and mounting, wiring and insulating all becomes a mere formality but it never took off. Then came the TO-220 and TO-247. These packages were pro­duced with PC boards in mind and the served this purpose well. TO-220 devices serve 90% or more of applications quite well as usually their power dissipation is low. With the advent of the HEXFET, the power or current rating has slowly been increasing over the last few years with the on-resistance falling. We now have 60A transistors in a TO-220 package which once would have been in a TO-36 case, which has far better heat transfer charac­ teristics and heavier leads. The normal equation or rule of thumb with these FETs is to divide the current, in this case 60A, by 4 and this will be the DC continuous current rating of the device (15A). This rating is determined by the ability to transfer the heat to somewhere else. The source lead of a TO220 case is somewhat smaller in cross sectional area than the equivalent piece of flexible wire that would carry 60A. Therefore unless I heatsink the source lead of a TO-220 package, then I am going to add considerable stress to the TO-220 package in the form continued on page 93 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings. Please feel free to visit the advertiser’s website: www.jaycar.com.au ORDER FORM BACK ISSUES MONTH YEAR MONTH YEAR PR ICE EACH (includes p&p) Australi a $A7.00; NZ $A8.00 (airmail ); Elsewhere $A10 (airmail ). Buy 10 or more and get a 10% discount. Note: Nov 87-Aug 88; Oct 88-Mar 89; June 89; Aug 89; Dec 89; May 90; Aug 91; Feb 92; July 92; Sept 92; NovDec 92; & March 98 are sol d out. 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Please have your credit card details ready OR Fax (02) 9979 6503 Fax the coupon with your credit card details 24 hours 7 days a week Mail order form to: OR Reply Paid 25 Silicon Chip Publications PO Box 139, Collaroy 2097 No postage stamp required in Australia October 1999  53 Semiconductor Curve Tracer This semiconductor curve tracer will allow you to dis­play the dynamic characteristics of semiconductors such as tran­sistors, FETs and diodes on an oscilloscope. It uses readily available parts and is easy to use. Design By CHARLES HANSEN* If you look through any semiconductor data book you will find that each device, be it a transistor, junction FET, MOSFET or zener diode, comes with a family of characteristics which tell a lot about its performance as circuit conditions are changed. This tester allows you to generate similar operating curves. It incorporates a collector supply and base step genera­ tor which together produce voltage and current signals that are applied to the device-under-test (DUT). The tester can be used to measure and display a number of bipolar-transistor parameters simultaneously. For example, it can be used to plot collector current (Ic) versus collector volt-age (Vce) characteristics of a tran54  Silicon Chip sistor, determine saturation vol­tage, calculate gain (hFE) and look at the spacing and slope of hFE curves. Nor is the Semiconductor Curve Tracer limited to bipolar transistors; it can also be used to test JFETs, MOSFETs, SCRs, diodes and zener diodes. The big picture Fig.1 is a block diagram of the Curve Tracer, with an NPN transistor shown as the DUT. The block diagram shows the two parts of the circuit, a collector supply and base step generator. The collector supply is essentially a low voltage transformer feeding a bridge rectifier. This supplies the collector current to the transistor as unfiltered DC. The base step generator feeds base current to the transistor, stepping it up in equal incre­ments, starting from zero and increasing to a maximum of nine steps. Note that the emitter of the transistor is grounded and so is one side of the base step generator. The collector supply on the other hand is fully floating which allows the DUT’s emitter to be grounded. Now let us consider current flow in the circuit. The col­lector current Ic flows from the positive side of the bridge rectifier into the DUT’s collector, out the emitter and via the emitter resistor Re back to the negative side of the bridge rectifier. The base step generator on the other hand produces a step current waveform which flows into the base of the DUT, back out through the emitter and then back to the negative side of the base step generator which happens to be grounded. This last point is most important because it means that the base current does not flow through the emitter resistor Re as it would in conventional transistor circuits. Hence, the current flowing through Re is only the collector current. The voltage waveform across Re is inverted by the fol­lowing op amp to correct its sense and then it becomes the Y signal to one channel of the oscilloscope. The collector voltage waveform becomes the X signal to the oscilloscope and the two are combined in a Lissajous display to produce the characteristic family of Ic vs Vce waveforms. Circuit description Fig.2 shows the circuit of Semiconductor Curve Tracer. It has four ICs, four transistors, 21 diodes, a fullwave bridge rectifier and two power transformers. At first sight, it bears no resemblance to the circuit of Fig.1 but stay with us and all will be revealed. The reason why the full circuit has two transformers is that it needs two completely separate power supplies; one to feed the base step generator and various op amps and the other to provide the collector supply circuit. The collector circuit uses transformer T2 which has a 12V centre-tapped winding which is switched by S4 before being fed to the bridge rectifier comprising diodes D18-D21. The resulting unfiltered DC of 10V or 20V (nominal peak voltage) is applied to two poles of a 3-position switch, S6a and S6c. Switch S6 allows the user to select one of three sweep modes: NPN, PNP or AC. The third pole of S6, S6b, is used to ground the base when the circuit is set for the AC mode. The collector current passed by the DUT is monitored by one of six resistors (Re) selected by switch S7 and the voltage across the selected resistor is inverted by op amp IC4b which has a gain of -1. Its output at pin 7 becomes the Y signal to the oscilloscope. The positions of switch S7 increase in a 1.2.5 sequence; ie, 1mA, 2mA, 5mA, 10mA, 20mA and 50mA. These values do not indicate the amount of collector current flowing but relate to the deflection sensitivity of the oscilloscope display; eg, 1mA/div, 2mA/div and so on. In use, S7 is set to produce the optimum Ic display. Base step generator The base step generator comprises a clock, counter, step-level converter and a step amplifier. The clock circuit consists of diodes D1 & D2 and transistors Q1 & Q2. Diodes D1 & D2 derive a 100Hz signal from the Fig.1: block diagram of the Curve Tracer, with an NPN transistor as the DUT. There are basically two parts to the circuit: a collector supply and a base step generator. This photo shows the collector current vs the collector-emitter voltage of an NPN transistor for different values of base current. The increments in the base current are produced by the step generator. secondary winding of transformer T1 and this is supplied to transistors Q1 & Q2 which turn on hard to provide a 100Hz square-wave clock signal to the 4017 decade counter IC1. Nine of its outputs are coupled via resistors and diodes which results in a step waveform with 1V increments and nine steps. Note that the first decoded output (pin 3) is not used and this represents Special Notice *This project and article has been adapted with permission from an article in the May 1999 issue of the American magazine Popular Electronics. The original design did not have a PC board and this has been produced by SILICON CHIP staff. the zero-level base step. The step waveform is fed to trimpot VR1 and op amp IC2a which functions as a unity gain buffer. Switch S3 is included to provide a 1V HOLD setting which is used to check the step genera­tor’s output during initial tests. IC2a drives two op amps, IC2b which is a unity gain invert­er and IC4a which is connected as a comparator. When the step signal at pin 3 of IC4a reaches the DC level set by potentiometer VR2, its output at pin l goes high, and this resets counter IC1 to zero via diode D13 and so the step waveform starts from zero again. In effect, VR2 is used to set the number of steps, up to the maximum of nine. Diode D13 is included to prevent any negative output vol­ tage swing from IC4a from damaging IC1. Switch S1 is used to select between positive polarity steps from IC2a or October 1999  55 negative polarity steps from IC2b. The step signal from S1 drives two circuits. The first is a voltage divider, which provides the gate voltage steps necessary to test FETs. So the first four positions of switch S2 provide step signal increments of 1V, 0.5V, 0.2V and 0.1V. The larger steps are required for power MOSFETs. Voltage to current converter In order to generate the base current steps required to test bipolar transistors, a voltage-to-current converter is required and that function is performed by the dual op amp IC3 and transistors Q3 & Q4. Note that the voltage-to-current con­verter produces an inverted output so S1 selects negative voltage steps to produce positive current steps and vice-versa. The eight output current steps are determined by the resistors selected by switch S2 and the steps are 5µA, 10µA, 20µA, 50µA, 0.1mA, 0.2mA, 0.5mA and 1mA. Finally, the output lines to the oscilloscope input chan­nels are fed via 560Ω resistors, to isolate the scope input ca­pacitance. Similarly, the connections to the collector and emit­ter of the DUT are isolated via ferrite beads. These measures are included to prevent the possibility of spurious oscillation in a device under test (DUT). The oscilloscope waveforms of Fig.4 demonstrate the opera­ tion of the Curve Tracer circuit. The bottom trace is the output of the base step generator while the top trace is the collector current waveform from the output of op amp IC4b. Apart from the already mentioned collector voltage supply involving transformer T2, the power supply of the Semiconductor Curve Tracer is quite conventional. Transformer T1 has a 24V centre-tapped secondary which feeds a bridge rectifier involving diodes D14-D17 to produce positive and negative supply rails. These are fed to positive and negative 3-terminal 12V regulators to produce ±12V. Construction The Semiconductor Curve Tracer is housed in a standard plastic instrument case measuring 260 x 190 x 81mm. There are two PC boards inside, one behind the front panel, accommodating all the circuitry on 56  Silicon Chip the righthand side of Fig.2, and one on the floor of the case, accommodating all the power supply circuitry. Before you begin assembly, check the PC boards for etching faults and for any undrilled holes. While these are relatively rare, it is much easier to check and fix them while the board is blank. PC board 1 Starting on PC board 1, fit the resistors and diodes first, followed by the transistors, regulators, PC stakes and capacitors. The component layout is shown in Fig.3. If you want to use a socket for IC1, fit it now, otherwise leave the 4017 until you have mounted the two power transformers. The PC board has been laid out for 2N2222 TO-18 metal can transistors but they may also be supplied as plastic TO-92 types. If you get the TO-92 type, bend the centre lead towards the flat before you insert them in the PC board. Both the power transformers are PC-mounting types but we do not solder the primary (240VAC) lugs to the board. Instead, bend the primary leads out and solder short lengths of mains-rated hookup wire to them. The secondary lugs are then inserted into the PC board holes and soldered. A cable tie is threaded through the holes in the PC board and used to anchor each transformer firmly in place. The primary wires are then connected to 2-way insulated terminal strips which also clamp insulating shields made of Elephantide to keep unwary fingers away from the mains. Fig.7 shows the dimenensions of the two shields. The tabs at either end fold back and go under the cable ties which secure the transformers. DO NOT OMIT THESE SHIELDS AS THE LIFE YOU SAVE MAY BE YOUR OWN. Check the polarity of the diodes, regulators and capacitors and then mount the board on the floor of the case using the four self-tapping screws. Front panel PC board The front panel board layout is shown in Fig.5. It is assembled in the same way as the main board, beginning with the links then the resistors Fig.2: the circuit has two completely separate power supplies: one to feed the base step generator (Q1, Q2 & IC1) and the various op amps and the other to provide the collector supply circuit. and diodes. The large number of odd value 1% resistors means that you should use your digital multi­meter to check each value as it is installed. We used PC stakes even though the external wires are soldered to the copper side of the board. This prevents the copper pads from lifting. The three rotary switches should be pushed hard against the PC board before soldering the pins. October 1999  57 Fig.3: the parts layout for PC board 1. The board has been laid out for 2N2222 TO-18 metal can transistors but they may also be supplied as plastic TO-92 types. Note that the pin configurations of the two types are different: if you get the TO-92 type, bend the centre lead towards the flat before you insert them in the PC board. Below: the fully-assembled front panel PC board. Note that the fuse (F2) is mounted on the copper side of the board, as shown in the photograph. 58  Silicon Chip The fuseholder and the trimpot are mounted on the copper side of the board to allow access to them. We did not fit the power LED at this stage but we did mount the step control potentiometer (VR2) on the PC board to allow initial testing. Once the tests are completed the LED can be fitted and VR2 can be mounted on the front panel. Don’t forget the wires from the pot lugs to the PC board. Before you solder the toggle switches in place, you must drill all the front panel holes. Use the front panel label as a template. The lefthand rotary switch (S6) must have its detent washer set for three positions (two clicks), then a nut fitted to hold it in position. The centre rotary switch (S7) must be set for six positions before the nut is fitted. The righthand switch uses all 12 positions and does not need a detent but you should fit a flat washer before the nut to keep the front panel spacing correct. Fit a nut and a star washer to each toggle switch and push it into the PC board. Make sure that the 3-position toggle switch (S5) is in the correct place. Mount the front panel on the rotary switches, using a second nut on each one, then make sure that the toggle switches protrude through the front panel far enough to get a nut on their threaded bushes. They should be pushed right up to the PC board but you may have to move them out a little to get everything just right. Once you are satisfied, solder the switch lugs, remove the front panel, fit the label if you haven’t already done so and put it to one side. It can be fitted after the unit has been tested and is working properly. We now come to the most critical stage, the mains wiring. As you can see from the wiring diagram of Fig.6, we have kept it simple. The mains switch is mounted on Fig.4: these oscilloscope waveforms demonstrate the opera­tion of the circuit. The bottom trace is the output of the base step generator, while the top trace is the collector current waveform from the output of op amp IC4b. the back panel close to the fuseholder and mains cord entry. We used a double pole switch, which ensures that both the Active and the Neutral are disconnected in the off position. Naturally, all the mains wir­ing, including that to the two transformers, must be run in 250VAC-rated hookup wire. Make sure you use a generous length of heatshrink to shroud the fuseholder and the switch. Each wire (or pair of wires in the case of the transformer leads) should be individually sleeved on the power switch before the larger outer sleeve is fitted. Twist the mains leads together as shown and secure them with cable ties, so that if a lead comes adrift, it can not contact any other parts. Also ensure that there are no strands of wire protruding from the terminal blocks on the PC board. We fitted two BNC connectors to the rear panel for connec­ tion to the oscilloscope, which means you will need two BNC to BNC coaxial leads. Quite often it is just as convenient to use the existing oscilloscope probes and to this end we have also fitted a couple of 3mm screws as tie points adjacent to, and wired in parallel with, the BNC sockets which lets you clip the probes straight onto them. Of course you will also need to clip the earth wire of one of the probes onto one of the BNC sockets. The wiring between the two boards must be run as shown in Fig.6. Testing Re-check your wiring between the two PC boards and make sure you have fitted the mains fuse in the fuseholder. Turn the mains switch on and read the resistance between the Active and Neutral pins on the mains plug. Our unit measured 214Ω and we would expect yours to be within 10% of this value. Also check for zero resistance between the Earth pin on the mains plug and the metal shells of the BNC connectors. Once these tests are satisfactory, apply power to the unit and check the ±12V rails from the 3-terminal regulators. Measure the DC voltage at the three PC stakes near the regulators on the main board. With the centre one as earth -12V should be present on the stake nearest the board edge and +12V on the other. Also check the AC voltages from transformer T2. If the AC is not present you have forgotten to solder a transformer pin or else the transformer is faulty. If the DC voltages Fig.5: the parts layout for the front panel board. October 1999  59 Fig.6: follow this diagram to install the mains wiring and to complete the external wiring to the PC boards and rear panel. Note that the two mains transformers have different secondary voltages, so don’t get them mixed up. 60  Silicon Chip Resistor Colour Codes  No.    1    1    1    4    1    1    1    1    1    1    1  13    1    1    1    4    1    1    1    2    1    2    1    5    2    1    2    2    2    1    2 Value 1MΩ 560kΩ 470kΩ 100kΩ 82kΩ 51kΩ 30kΩ 27kΩ 22kΩ 15kΩ 12kΩ 10kΩ 8.2kΩ 7.5kΩ 5.6kΩ 5.1kΩ 3kΩ 2.7kΩ 2.4kΩ 2.2kΩ 2kΩ 1.8kΩ 1.5kΩ 1kΩ 560Ω 510Ω 200Ω 100Ω 51Ω 20Ω 10Ω 4-Band Code (1%) brown black green brown green blue yellow brown yellow violet yellow brown brown black yellow brown grey red orange brown green brown orange brown orange black orange brown red violet orange brown red red orange brown brown green orange brown brown red orange brown brown black orange brown grey red red brown violet green red brown green blue red brown green brown red brown orange black red brown red violet red brown red yellow red brown red red red brown red black red brown brown grey red brown brown green red brown brown black red brown green blue brown brown green brown brown brown red black brown brown brown black brown brown green brown black brown red black black brown brown black black brown 5-Band Code (1%) brown black black yellow brown green blue black orange brown yellow violet black orange brown brown black black orange brown grey red black red brown green brown black red brown orange black black red brown red violet black red brown red red black red brown brown green black red brown brown red black red brown brown black black red brown grey red black brown brown violet green black brown brown green blue black brown brown green brown black brown brown orange black black brown brown red violet black brown brown red yellow black brown brown red red black brown brown red black black brown brown brown grey black brown brown brown green black brown brown brown black black brown brown green blue black black brown green brown black black brown red black black black brown brown black black black brown green brown black gold brown red black black gold brown brown black black gold brown are not right check the diode and capacitor polarities as well as the regulator orientation. Using the curve tracer The front panel board has been laid out so that when all the toggle switches are down (on) you have the safest mode to measure a transistor. The collector DC supply is set to Fig.7: this diagram shows the dimensions of the two Elphantide insulating shields which cover the mains terminals of the power transformers. This photo shows how the front panel is attached to the vertical PC board by fitting it over the switch shafts. October 1999  61 Fig.8 (left): this is the full-size artwork for the front panel. Above: although not shown here, the mains wiring should be secured with cable ties so that if a lead does come adrift, it cannot contact other parts. 62  Silicon Chip Above: the two screws adjacent to the BNC sockets on the rear panel are intended to take CRO clips leads if you don’t have a BNC-to-BNC cable. Table 1: Test Connections Device Collector Polarity Step Polarity BIPOLAR N PN PN P +NPN -PNP + - JF E T N-Channel P-Channel +NPN -PNP + - MOSFET N-Channel P-Channel +NPN -PNP + - Parts List 10V, the collector has the 100Ω load resistor switched in, the steps are set to normal and the polarity is set for an NPN transistor. Both X and Y channels of your oscilloscope must be DC-coupled but because the frequencies being displayed are quite low in frequency, you don’t need a wide bandwidth on any of the channels. The scope’s vertical input should be set to the 0.1 volt/div scale to provide proper collector current readings as indicated by the scale of switch S7. The scope’s horizontal input should be set to the 1V/div scale to provide appropriate collec­tor-emitter voltage readings. If you are using a single channel scope, turn the timebase switch to the X or external position. A two-channel scope with an XY timebase switch position can use one channel as the X channel and the other as the Y channel. Table 1 gives the scope connections and polarities for bipolar and field-effect devices; that table can be modified as required (to match your 1 PC board, 152 x 106mm, code 04110991 1 PC board, 239 x 71mm, code 04110992 1 plastic case, 260 x 190 x 81mm 1 12-0-12V PC-mounting power transformer (T1); Altronics M-7124 or equivalent 1 6-0-6V PC-mounting power transformer (T2); Altronics M-7112 or equivalent 1 DPDT PC-mounting toggle switch (S1) 1 single-pole 12-position PC mounting rotary switch (S2) 2 SPDT PC-mounting toggle switch (S3,S4) 1 single-pole 3-position PCmounting centre-off toggle switch (S5); Altronics S-1332 or equivalent 1 3-pole 4-position PC-mounting rotary switch (S6) 1 2-pole 6-position PC-mounting rotary switch (S7) 1 DPDT panel-mount mains rocker switch (S8) 1 3AG safety fuseholder 1 500mA 3AG fast-blow fuse (F1) 1 500mA M205 fast-blow fuse (F2) 2 M205 PC-mount fuse clips 1 250VAC mains cord with moulded 3-pin plug 1 cordgrip grommet to suit mains cord 2 chassis-mount BNC connectors 3 22mm knobs; Jaycar HK-7022 or equivalent 1 16mm knob; Jaycar HK-7020 or equivalent 1 5kΩ horizontal trimpot (VR1) 1 10kΩ 16mm PC-mounting potentiometer (VR2) 1 red banana socket 1 red banana plug 1 black banana socket 1 black banana plug 1 yellow banana socket 1 yellow banana plug 2 small ferrite beads scope) and attached to the top of the tester as a reference. The step polarity and the collector vol­tage polarity switches should be set to suit the DUT. CAUTION: some of the Curve Tracer’s controls, if set too high, could cause damage to the DUT. Its base current capability is high enough to drive most power transistors to maximum collec­tor current. If the Curve 2 2-way light-duty insulated terminal blocks 4 3mm x 10mm M3 screws 6 3mm M3 nuts 4 3mm toothed washers 4 6g x 6mm self-tapping screws 4 100mm cable ties Hookup wire, tinned copper wire Semiconductors 1 4017 decade counter (IC1) 2 LF412 dual low-offset op amps (IC2, IC3) 1 NE5532 dual op amp (IC4) 2 2N2222 NPN transistors (Q1, Q2) 1 BC639 NPN transistor (Q3) 1 BC640 PNP transistor (Q4) 1 7812 12V regulator (REG1) 1 7912 -12V regulator (REG2) 1 5mm green LED (LED1) 13 1N914,1N4148 small signal diodes (D1-D13) 8 1N4004 power diodes (D14-D21) Capacitors 2 470µF 25VW PC electrolytic 2 10µF 16VW PC electrolytic 3 0.1µF monolithic ceramic 2 27pF ceramic disc Resistors (0.25W, 1%) 1 1MΩ 1 3kΩ 1 560kΩ 1 2.7kΩ 1 470kΩ 1 2.4kΩ 4 100kΩ 2 2.2kΩ 1 82kΩ 1 2kΩ 1 51kΩ 2 1.8kΩ 1 30kΩ 1 1.5kΩ 1 27kΩ 5 1kΩ 1 22kΩ 2 560Ω 1 15kΩ 1 510Ω 1 12kΩ 2 200Ω 13 10kΩ 2 100Ω 1 8.2kΩ 2 51Ω 1 7.5kΩ 1 20Ω 1 5.6kΩ 2 10Ω 4 5.1kΩ Note: all rotary switches require two nuts. Tracer is set to the high collector-supply-voltage range and the 50mA/div range at the same time, the connected transistor can heat up rapidly and could be destroyed. Be sure to always double-check the pinout of all devices and make sure that the correct collector-voltage polarity and base-step polarity are applied to the DUT. SC October 1999  63 AUTONOMOUSE HEROBOT T   Last month, we described the three separate PC board assemblies that make up the Autonomouse. This month, you have to assemble these to form a chassis, mount the two motor/ gearbox assemblies, fit the wheels and complete the wiring. Part 2: By JOHN CLARKE T HE MOTOR/GEARBOXES are mounted on the copper side of board 3, as shown in Fig.10. Each unit is located with two 6mm tapped spacers near the drive shaft and two 9mm spacers at the motor end. Two mounting plates (20 x 35mm) cut from PC board or similar material are used to clamp the motor ends of the drives in place with 9mm long M3 screws. The standoffs are secured to the front of the PC board with M3 x 6mm screws. Note that some holes are close to adjacent PC tracks and you should use insulat­ ing washers under any screw or spacer which could cause a short between tracks. Rear panel Cut a piece of double-sided PC board 114 x 69mm and posi­tion it at right angles along the back edge of board 1, adjacent to the 2200µF capac64  Silicon Chip itor. It should protrude by about 1mm below board 1’s edge so the two edges can be soldered together. The right angle assembly should then be braced with a strip of 35mm long 0.75mm sheet brass, soldered to both board edges, as shown in one of the photos. Wheels & castor Making the wheels requires a little ingenuity. You could use wheels from a toy or make them from turned wood. We made ours by cutting the cheeks off two 200g Multicore solder reels. Each wheel was made by clamping two cheeks together with a 30mm alu­ minium hub on each side. The resulting wheels were 64mm in dia­meter, to give sufficient ground clearance for the robot. To attach the wheels to the drive shafts, we drilled a hole in the centre of the hubs which were slightly too small for the 15mm long tapped spacers which were then pressed into the hubs using a vice. The tapped spacers were then soldered to the gear­ box drive shafts. While we went to the trouble of making our own trailing castor, it turns out that you can buy a 30mm castor from hardware stores. You will need to make up the castor mounting brack­et for it though. This consists of a 40 x 60mm piece of single-sided PC board and two 40 x 40mm right-angle triangular pieces of PC board attached as shown in Fig.11. You will need to drill four holes in the main piece to mount the castor. The three pieces can be soldered together and the castor mounted on it but the assembly is not soldered to the rear panel of the robot just yet. Attach 15mm spacers to the front of board 3, the top of board 2 and top Fig.10: this diagram shows how the battery carrier sits above board 2 and how the motor drives are clamped to the copper side of board 3 using two mounting plates cut from PC board material – see text. October 1999  65 This is what the chassis looks like prior to fitting board 2 into position. Note how the motors are attached to board 3 which sits at the front of the unit, between the two large driving wheels. of board 1 using M3 x 6mm screws. Now secure the LED1 edge of board 3 to the transistor end of board 1 using a couple of short lengths of tinned copper wire soldered to the copper side of both boards. The soldering should be done to allow the wire to bend as a hinge joint. Mind you, you cannot bend it often otherwise the wires will break. The next job is to cut out the battery mounting plate. This measures 75 x 110mm and can be made from plastic or metal, etc. Drill holes in the corners to suit the stand­offs on board 1. Wiring it up This under-chassis view shows how three wire loops are fitted to the leading edge of board 1. The looped ends of these are soldered to the bottom of board 3 which has to be pushed against board 1 (the boards here are shown separated). 66  Silicon Chip Wire up the robot as shown in the diagram of Fig.12. Make sure that the various interconnecting wires are long enough to pass under the battery mounting plate which mounts on top of the spacers on board 1. You will need to drill holes in the rear panel for the switch and flashing LED. The LED mounts on the rear panel within the castor mounting bracket in a 5mm bezel. Solder two 9mm tapped brass spacers to the sides of the triangular bracket to support the red acrylic. Place the battery platform in position and attach it with four M3 x 6mm screws. Board 2 goes on the top of the assembly so far. So solder board 2 to the vertical edge of board 3 and to the rear panel, at the corners. Just tack-solder the boards at the corners. If you apply a lot of solder it will be difficult to disassemble the robot if you have to do any troubleshooting. The two wheels for the robot can be permanently soldered in place after the drive-shafts have been cut to length. Make sure that there is sufficient clearance for the wheels before cutting. The shaft ends are then soldered to the brass spacers in the wheel hubs. Now that the wheels are in position, you can solder the castor bracket to the rear panel. Make sure that the robot will be level when sitting on its wheels and castor. Bend IRD1 and IRD2 so that they face toward the outside corners and adjust IRLED1 and IRLED3 to the same angle. IRLED1 & IRLED3 should have short lengths of black plastic tubing over them to prevent the light from the sides being received. Testing Attach the battery packs with switch S1 off, then wind VR3 & VR4 (on the underside of the robot) fully clock­ wise. This will prevent the motors from running for the time being. Now switch on the power. The LED chaser at the front of the robot should be running from top to bottom and the rear LED should be flashing. If not, switch off power and check your wiring. Next, rotate VR2, on top of board 2, fully clockwise. Now place your hand about 60mm away from the IRLED3 and IRD2 pair and slowly adjust VR1 until the circular chaser starts up. Move your hand further away and adjust VR1 again to start the chaser. If the front chaser goes backward during these tests, you will need to take your hand away and wait for this reversing Fig.11: the castor bracket is made using single-sided PC board material, while double-sided PC board material is used for the rear panel. You can attach the castor either by using four screws and nuts or by gluing it. The two battery holders sit on an elevated plastic shelf attached to board 1. Power comes from eight AA alkaline cells. October 1999  67 Fig.12: this diagram shows how the three PC boards are wired togeth­er. Make sure you leave the wires long enough to pass under the battery carrier on board 1. action to stop before you can readjust VR1. You should be able to get a range of about 100mm although wheth­er that much is really necessary is debatable. Any sensitivity adjustments should now be done with VR2. Turning VR2 anticlock­wise will reduce the sensitivity. Adjust trimpots VR3 & VR4 to start the motors running. Adjust them to 68  Silicon Chip run at the same speed. Note that the wheels may be operating in the wrong direction in which case you simply swap the motor leads. Check that the robot runs on the floor and will turn away from obstructions. Adjust the speed to give smooth running. You will find that the robot runs best on smooth flooring and will tend to stall on carpet. Adjust the sensitivity for best re- sults. Low sensitivity to obstacles gives best results when the robot is running down a hallway. Note that the robot may not respond well to obstacles which are very dark or highly textured, such as cushions. This is because the infrared light is absorbed rather than reflected back to the robot sensors. Finally, place the red acrylic on the robot. The 60 x 90mm piece is for ELECTRONIC COMPONENTS & ACCESSORIES •  RESELLER FOR MAJOR KIT RETAILERS •  PROTOTYPING EQUIPMENT •  CB RADIO SALES AND ACCESSORIES •  FULL ON-SITE SERVICE AND REPAIR FACILITIES •  LARGE RANGE OF Ph (03) 9723 3860 Fax (03) 9725 9443 Come In & See Our New Store M W OR A EL D IL C ER O M E ELECTRONIC DISPOSALS (COME IN AND BROWSE) Truscott’s ELECTRONIC WORLD Pty Ltd ACN 069 935 397 27 The Mall, South Croydon, Vic 3136 email: truscott<at>acepia.net.au www.electronicworld.aus.as We made our own trailing castor but you can buy a 30mm castor from hardware stores. You will need to make up the castor mounting bracket for it, though. P.C.B. Makers ! If you need: •  P.C.B. High Speed Drill •  P.C.B. Guillotine •  P.C.B. Material – Negative or Positive acting •  Light Box – Single or Double Sided – Large or Small •  Etch Tank – Bubble or Circulating – Large or Small •  U.V. Sensitive film for Negatives •  Electronic Components and •  •  This photo shows how the motor ends of the drives are clamped to board 3 sing standoffs and two pieces of PC board material. the front, the 60 x 140mm piece is for the top and the 60 x 59 piece is for the tail. These are secured with M3 x 6mm screws secured into the standoffs through holes in the acrylic. Your Autonomouse can now be let loose, to wander about at will. Have SC fun! Equipment for TAFEs, Colleges and Schools FREE ADVICE ON ANY OF OUR PRODUCTS FROM DEDICATED PEOPLE WITH HANDS-ON EXPERIENCE Prompt and Economical Delivery KALEX 40 Wallis Ave E. Ivanhoe 3079 Ph (03) 9497 3422 FAX (03) 9499 2381 •  ALL MAJOR CREDIT CARDS ACCEPTED October 1999  69 PRODUCT SHOWCASE Code-Hopping High Security UHF Remote Switch from Altronics Altronic Distributors (Perth) have available a high security but relatively low cost UHF remote switch. It offers three operating modes and a code-hopping data signal which prevents the code being “learnt” by close-by receivers. 387 billion code combinations are possible. Altronics have already found a ready market in medium to high security alarm installations and remote control devices requiring a high level of security. Operation is in the 433MHz UHF band and the receiver operates from a nominal 12V DC supply (not included). The transmitter is keyring-sized and features two push buttons. Button A or B can be pressed individually or both buttons together for the third mode. The UC-215 receiver is similarly small in size (100 x 72 x 27mm) with either an internal antenna or a small (10cm) external antenna. A higher gain external antenna (50Ω) can also be connected for longer range. With standard antenna, the range is around 30 metres. There are two relay outputs which can be set up to momentary (1 second) or latch operation. The third output is via an on-board transistor. With a recommended retail price of $110 including one keyring transmitter, the Cat. A-1018 UHF Remote Control Switch is available from the Altronics retail store in Perth (Mail Orders freecall 1800 999 007). Trade enquiries to Altronic Distributors, 174 Roe St Perth (Phone 08 9328 2199, Fax 08 9328 4459). Ultra DMA 66 HDD PCI IDE Controller Microgram Computers have the answer for users who want to add fast, large hard disks to older motherboards: their Ultra DMMA66 IDE controller has two enhanced Ultra DMA 66 IDE ports, supports up to four IDE devices and co-resides with existing motherboard IDE controllers. This enables users to break the 8.4GB drive barrier and also use the higher speed UDMA66 drives. It is supplied with a two-drive cable and drivers for both Windows 9x and NT4. For more information, call Microgram Computers on (02) 4389 8444, fax (02) 4389 8388, or visit the website www. mgram.com.au 70  Silicon Chip Voice Recognition Module Supplier In response to many enquiries from S ILICON C HIP readers after the publication of the Voice Recognition Experimenter’s Kit in the August 1999 issue, the Australian distributors of Sensory Inc. products, Adilam Electronics, have announced that they will be selling the Voice Recognition module used in the project for A$80.00 + $12 for delivery anywhere in Australia. This compares very well to the U$50.00 that is shown on the Sensory Web site. It will be much easier to purchase the module from Adilam and it will probably cost less than buying them direct from Sensory. Adilam will ship by overnight delivery. Please contact your closest Adilam Electronics office: Melbourne (03) 9761 4466; Sydney (02) 9584 2755; Brisbane (07) 3377 9555; Adelaide (08) 8212 6665; Perth (08) 9274 0522; Christchurch (NZ) (03) 366 2577. Bargain phone answering machine from Oatley Maintaining their reputation as the place to go for a bargain, Oatley Electronics has purchased a job lot of fully-featured, Austel-approved Telephone Answering Machines, ready to plug in and use, and are selling them for $25.00 each – including a tape, manual, phone lead and plug-pack supply. The TAM features one-touch operation, power fail protection, VOX recording, remote message retrieval and has music playing before the beep tone. It can also be used as a remote room monitor. It measures 120 (W) x 175 (D) x 55mm (H) and is only available from Oatley Electronics, PO Box 89 Oatley NSW 2223. Phone (02) 9584 3563, Fax 9584 3561, or email oatley<at>world.net Oatley Electronics now has a retail shop open on Friday afternoons and Saturday mornings for surplus and special sale items. The address is unit 5, 51b Anderson Rd, Mortdale. MAX CDPAK: CD, DVD & laser disk repair kit While audio CDs, data CD-ROMs, laser disks, photo CDs and DVD have enjoyed massive acceptance and usage, early claims about their nearbullet-proof surfaces have proved not to be the case. CDs can easily be scratched and, especially in the case of data CDs, the content damaged or even lost. With this in mind, DIA Multimedia Distribution has released the MAX CD PAK, a repair and maintenance kit designed to clean and maintain all the common disc formats in use today. The kit includes a bottle of CD Quick Clean to clean and protect the disc surface, a pack of CD Quick Wipes for a quick clean-up and the CD Playright repair kit itself, a scratch repair system which can “fix” up to 12 CDs. In addition there’s a 20-CD flipstand and three spare CD jewel cases. PCB POWER TRANSFORMERS 1VA to 25VA The kit has a recommended retail price of $59.95 and will be available from record stores and CD retailers shortly. All items are also available individually. Trade enquiries should be directed to DIA Multimedia Distribution, 748 North Rd, Ormond East, Vic 3204. Tel (03) 9576 7122, Fax (03) 9576 7011. New 3dfx Voodoo3 3500 Mini DIN relay from TV graphics accelerators Siemens Innovision, the sole Australian importer of Voodoo 3 graphics accelerators and 3dfx produces, has announced a new top-end model to the top-selling range. The Voodoo3 3500TC gives maximum PC graphics performance, creating superior graphics quality/realism and ineractivity. Based on the acclaimed Voodoo3 graphics accelerator technology, the new card combines the most powerful 3D and 2D graphics with complete TV tuner and multimedia functionality, all on a single AGP board. It supports MPEG2, DVD and high-resolution displays and will allow DVD movies to be played at 30 frames per second. Operating at 183MHz, it has a resolution up to 2047 x 1536 pixels. Voodoo3 accelerators are available at leading computer retailers throughout Australia. For more information, contact Innovision Technology on (03) 9853 6389, fax (03) 9853 84709. Looking for a small, high capacity relay? This new Schrack-relay PT from Siemens Electromechanical Components (Siemens EC) could fit the bill. It’s just 29mm high but comes with two, three or four changeover contacts capable of switching twelve, ten or six amps respectively. Each is available with an AC or DC coil and with plug-in or PC board terminals. Further details and specifications from Siemens EC via email, infoserv<at> scn.de Manufactured in Australia Harbuch Electronics Pty Ltd 9/40 Leighton Pl. HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 Digital Reader for Maps Dick Smith Electronics has a handy Map Measuring Meter which accurately measures the distance between two points on a map, plan or even a physical object. The user simply traces the line or path to be measured with the serrated wheel on the instrument, with the length in millimetres shown on the digital display. An inbuilt calculator can then be used to scale the reading to true units. There’s also a magnifying glass to make map reading even easier. With a recommended retail price of $39.95, the Cat Q-1399 Digital Map Measuring Meter is available from all Dick Smith Electronics stores and resellers or via mail order on 1300 366 644. CD-R, CD-W discs from $2.10 each Jaycar Electronics have introduced new ranges of recordable and rewritable CDs with prices for the CD-R as low as $2.10 each in 100-packs without jewel cases. The “Platinum” range of recordable CDs is silver/silver with 650MB/74 minute capacity. Single discs start at $2.85 in jewel cases. The “Avalon” CDs are rewritable and are priced at $7.95 each or $6.95 each for ten or more. The discs are available at all Jaycar Electronics stores and resellers throughout Australia. For more information contact Jaycar Electronics, (02) 9743 5222. October 1999  71 High Performance LeCroy colour ’scopes The new LeCroy LC684D family of digital oscilloscopes (DSOs), available from Trio Electrix (the new LeCroy representative for Australia and New Zealand) feature a 10.4" flat panel color display, 1.5GHz bandwidth and sampling rates up to 8GS/s. They also offer long memories (up to four Mbytes per channel or 16 Mbytes on a single channel) to capture complex signals with better accuracy and improve the ability of the DSO to zoom in on important details. The oscilloscopes start with 1.5GHz front end amplifiers and 2GS/s ADCs on each channel (cascadable to 8GS/s on a single channel). In addition, these DSOs contain proprietary trigger ICs which allow users to trigger on 600psec. This is useful in debugging both high-speed digital and analog circuits. They can also “play” a zoomed version of the signal in forward or reverse without the need to turn any knobs. All oscilloscopes in the LC series offer a display mode that emulates the brightness graded intensity of analog scopes –even for single shot signals. For more details on the LeCroy range of oscilloscopes, contact Trio-Electrix, PO Box 1158, Baulkham Hills, NSW 1755 Phone. 02-9836-0072 Multifunction DMM test probe If you use a multimeter, you know how handy a third hand and 25 fingers could be. Jaycar Electronics can’t give you that, but this DMM probe is the next best thing. It’s compatible with all DMM and analog meters and gives audible and visible warnings for a variety of functions. What’s more, there’s an inbuilt light for those dark PC board corners. It's priced at $8.95. For more information, contact Jaycar Electronics, 8-10 Leeds St, Rhodes, NSW 2138, Phone (02) 9743 5222, or any Jaycar ElectronSC ics store. IN YOUR NEXT ISSUE OF Items planned for the November issue*, due on sale at your newsagent October 27. Subscribers receive their copies a little earlier. FOLDBACK SPEAKERS Essential for all live performances . . . but have you ever tried to buy a set? Sure you can get them. If you have deep pockets, that is! Build your own top quality foldbacks and enjoy the difference! PIC-BASED TINY SPEED ALARM It all goes into a case 80 x 52 x 30mm so it will fit anywhere. And it could save you big $$$ in speeding fines. A must for every driver these days! * These features currently in production but are subject to alteration Even more great projects to build: • Programmable Robot • Micro-controlled XMAS TREE Plus all the popular features: • Serviceman's Log  •  Circuit Notebook   • Computer hints & tips •  Vintage Radio  • Product Showcase  •  Ask SILICON CHIP  SUBSCRIBE TO SILICON CHIP AND NEVER MISS AN ISSUE As a subscriber, you will not only receive your copy earlier – you will actually save money - AND SILICON CHIP picks up the postage! And don't forget, as a subscriber, you qualify for a 10% discount on all SILICON CHIP merchandise (subscriptions excepted!) Do you want YOUR product or service showcased to Australasia's most important electronics marketplace? 72  Silicon Chip CALL ME: RICK WINKLER on (02) 9979 5644 and let me explain how cost effective the SILICON CHIP ELECTRONICS SHOWCASE can be for YOU! L LECTRONICSHOWCASELEC SPEAKER SALE For the very first time we are having a sale of selected loudspeaker drivers from the prestige MOREL line. On sale are two drivers: UNIVERSAL WIRELESS DEVELOPMENT SYSTEM Linx RF modules from Clarke & Severn Electronics offer a simple, efficient and cost-effective method of making a product wireless. Want to know more? Contact CLARKE & SEVERN ELECTRONICS PO Box 1, Hornsby NSW 1630 Ph (02) 9482 1944 Fx 9482 1309 email: sales<at>clarke.com.au www.clarke.com.au MW 265 EMC Technologies' internationally recognised Electromagnetic Compatibility (EMC) test facilities are fully accredited for emissions, immunity and safety standards. 222mm Shielded Woofer, Fs 30Hz ,Vas 88.6L Qts 0.44 Power 150W Hexatech voice coil Normally $190 EMC Technologies DMS 30S Melbourne: (03) 9335 3333 Sydney: (02) 9899 4599 Failed hard disk drive? OLD out, NEW in EASY NOW $130 27mm Shielded Dome Tweeter, 94mm dia. Fs 650Hz Power 200W Hexatech voice coil Double chambered Sens 90dB Normally $129 NOW $75 All other MOREL products available – many ex-stock We are sole Australian Distributors for: Hot-Swap IDE RAID Array Cat. 2808 •  CLIO Electro-Acoustic Measurements •  SOFIA Vacuum Tube Curve Tracer •  JASPER Power Router Circle Jigs $1299 Australian Audio Consultants PO Box 11, Stockport SA 5410 Web site: Email: Phone / Fax 08-85-282-201 E-mail aac<at>rbe.net.au www.mgram.com.au info<at>mgram.com.au BUSINESS FOR SALE: SWITCHMODE POWER SUPPLIES 25W500W Extensive Range Escape to the sun in beautiful Coffs Harbour! • • • • •   • • •   • Stable electronic retail business Easily run by husband and wife team. Agent for GSM carrier Access to large electronics suppliers (niche market). Very strong customer base inc Government depts and schools etc. Five year rental option on current highway premises. Full figures available. Current owners (12 years) are moving to a new business. Price only $55,000 + SAV. Enquiries: phone (02) 6652 5684 or fax (02) 6651 3731 R.T.N • Basic Stamps, SX chips and tools. • OZ-made boards and development tools • Best pricing on temp, a/d, rtc kits • New Xilinx PLCC44 development system • New OZ made serial LCD module 2*16 • Stepper and R/C servo motor chips • New super catalog on CD Rom with 40 meg of  Stamp related data. Now available via SAE and  our cost $4.50, or free with orders over $125 Phone/Fax 03-9338-3306 HTTP://people.enternet.com.au/~nollet Email: nollet<at>mail.enternet.com.au MicroZed Computers GENUINE STAMP PRODUCTS FROM Scott Edwards Electronics microEngineering Labs & others Easy to learn, easy to use, sophisticated CPU based controllers & peripherals. PO Box 634, ARMIDALE 2350 (296 Cook’s Rd) 6 Sarich Court, Technology Park, Bentley WA 6102 Ph: 08 9470 1177 Fax 08 9470 2844 web: www.computronics.com NEW FROM QUESTRONIX DVS5 Video & Audio Distribution Amplifier Ph (02) 6772 2777 – may time out to Mobile 0409 036 775 Fax (02) 6772 8987 http://www.microzed.com.au Most Credit Cards OK DVS5 Video & Audio Distribution Amplifier VGS2 Graphics Splitter Five identical Video and Stereo outputs plus h/phone & monitor out. S-Video & Composite versions available. Professional quality. VGS2 Graphics Splitter High resolution 1in/2out VGA splitter. Comes with 1.5m HQ cable and 12V supply. Custom-length HQ VGA cables also available. Check our NEW website for latest prices and MONTHLY SPECIALS www.questronix.com.au Email - questav<at>questronix.com.au Video Processors, Colour Correctors, Stabilisers, TBC's, Converters, etc. QUESTRONIX All mail: PO Box 548, Wahroonga NSW 2076 October 1999  73 Ph (02) 9477 3596 Fax (02) 9477 3681 Visitors by appointment only CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates. Audio distribution amplifier This circuit allows a balanced audio feed to be distributed to multiple points, such as in a sound studio. Very low noise figures and a good frequency response were required so the circuit was designed using NE5534AN op amps throughout. The outputs will deliver up to +16dBm into a 600Ω balanced load, which is more than sufficient for most applications. The 10kΩ pot marked CMR allows for adjustment of common mode rejection and the gain pot allows the output to be trimmed to the correct level. It is important that the BD139/140 pairs in the output stages be mounted on suitable heatsinks, as they will get quite hot when driving at high levels. S. Williamson, Hamilton, NZ. ($30) Automotive fuse monitor This circuit came about after an incident with the family car, which could have cost an engine. While driving in the city in winter, in pouring rain, I noticed steam evaporating off the bonnet and it drew my attention to the temperature gauge which was steadily climbing. There is no idiot light in the VN Commodore to warn of an increase in temperature. In turned out that the fuse supplying the radiator-cooling fan was blown. However, if the blown fuse was not discovered in time, the result would have been a cooked engine. This is why this fuse monitor was developed but it could be used to monitor any fuse in a 12V circuit. Op amp IC1 is wired as a comparator with its non-inverting input (pin 3) referred to +6V while the inverting 74  Silicon Chip input (pin 2) is connected to the output side of the fuse being monitored. While ever the fuse is intact, pin 2 is above pin 3 and the output (pin 6) is low. If the fuse blows, pin 2 will be low and pin 6 will go high, to turn on transistor Q1 to operate the warning buzzer and light up LED1. Switch S1 is included to defeat the audible alarm but leaves the LED lit until the fault condition is resolved. A. Dollin, Taree, NSW. ($30) Low cost SLA battery charger This circuit was built to take advantage of low cost 14V DC plugpacks and power Mosfets currently available from Oatley Electronics. Essentially, power Mosfet Q1 works as a current source to charge the battery at a rate set by the voltage applied to its gate. This is limited to 10V by ZD1. As the voltage across the battery rises, the zener diode string comprising ZD2, ZD3 and D2 will ultimately conduct and turn on transistor Q2 because of the voltage impressed across the 1.2kΩ resistor between its base and emitter. Q2 then turns on Q3 and this removes the gate voltage from Q1, turning it off and stopping the charge. In practice, the prototype circuit provides full charge to the battery if its voltage is below 13.46V and the charge is progressively cut off as the battery voltage rises to 13.72V. The circuit then pauses until the battery voltage drops back to 13.46V whereupon full charging resumes for 10 seconds or so and then the cycle repeats. The bipolar transistors can be virtually any small low signal types while the Mosfet was a BUK453. Zener diodes ZD2 & ZD3 must all be 1W types which normally operate with about 10mA but here they operate at about 0.5mA, close to their “knee-point” voltage in the sensing circuit. The LED lights brightly when the circuit stops charging and dimly when it is charging. The 10V zener protects the gate of the Mosfet as the input from the 12V DC plugpack may be 18V or more. The charge current to low-capacity SLA batteries can be limited by placing a suitable power resistor in series with the positive or negative lead to the plugpack. Finally, the cut-in and cutout operation of the circuit may be changed by altering the value of the 1.2kΩ base-emitter resistor for Q2. Victor Erdstein Highett, Vic. ($30) 18W fluorescent light inverter uses ferrite rod This fluorescent light inverter uses just one transistor and a transformer wound on a ferrite rod. The clever component is the transformer; it performs three functions. Firstly, it acts as a feedback component for the transistor to create an oscillator circuit. Secondly, it provides a high voltage (over 2kV) to strike the fluorescent tube and thirdly it supplies energy to keep the tube illuminated. The transformer has three windings. The 20-turn primary is switched by the transistor and the resulting primary voltage of around 24V peak-to-peak (plus considerable spikes) is stepped up in the 960-turn secondary. Positive feedback is applied from the third winding to the base of the transistor to ensure that the circuit oscillates continuously. The ferrite core of the transformer is an antenna rod from a transistor radio. You can use a slab antenna but I chose to use an antenna rod 6cm long and 9mm in diameter. The primary winding is the first to be wound, on 45mm of the rod, using 20 turns of 0.5mm diameter enamelled copper wire. Use grease-proof paper as the interlayer insulation. The second winding is the feedback winding and consists of six turns of 0.3mm wire wound in a spiral fashion so that it is lies over the full length of the primary winding. The secondary winding consists of 960 turns of the 0.3mm wire. The feedback winding must be connected the right way around so that the transistor gets positive feedback. When first powered up, connect the 3Ω safety resistor in the positive line and connect the feedback winding. Then turn the circuit on and off very quickly and if the fluorescent tube doesn’t come on immediately, the feedback winding is the wrong way around. The safety resistor allows a limited current to flow through the circuit and the transistor will not be damaged. Once the correct feedback connection has been established and the fluorescent light comes on correctly, remove the 3Ω resistor and the circuit is ready to use. However, you must not use the circuit without the fluorescent tube connected because it provides loading for the transformer and has a damping effect on the spike voltages applied to the transistor’s collector each time it switches off. J. Draper, Glenview, Qld. ($30) October 1999  75 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG Jim Birtchnell and his radios This month, we meet a keen collector of vintage radios and discuss some of his favourite sets, or rather, what could be anyone’s favourites. The sets range from the early 1920s right up to the 1960s and most have been restored to a high standard. Meet Jim Birtchnell. Vintage radio collectors and restorers all start their hobby – or is it a passion? – from a point of not knowing much about it. Many start through reading columns such as this in electronics magazines, others through friends or just happening to go to an event where vintage radio may be one of several activities featured. Interests will probably change from the time of taking up the hobby, as the collector gets firmly established in the pas­time. Often one wonders what other collectors do and would like to know a little about them, and how they go about various activ­ities within the hobby. This is the reason for this month’s article. Jim started to get serious about vintage radio in about 1990. He has had a working knowledge of radio all his life, stretching back to an earlier time when Howard Radio of Richmond in Victoria manufactured radios. Jim has certainly seen many developments in radio during his life. He admits to being 84 and I’d say a youngish 84 at that, being fit and keen on his many Radiograms produced in the 1950s were fine pieces of cabinetwork, as demonstrated by this example. What’s that PC monitor doing on top of the gramophone? 76  Silicon Chip hobbies. He was a bit camera-shy, so the reader won’t get a look at this handsome fellow. Many collectors are members of vintage radio clubs and Jim is no exception. He is a member of the Vintage Radio Club of North East Victoria Inc which has about 30 members. Jim joined the club in around 1994 and this is where I got to know him. He has been a regular at the meetings and contributes in various ways with interesting equipment he brings along for the “show and tell” sessions or getting involved in the buy, sell and general horse-trading that goes on between members from time to time. Jim’s Collection His collection features around 65 sets that have been re­ stored, ranging from an Atwater Kent model 20 5-valve TRF (tuned radio frequency) set from the 1920s to HMV Little Nipper 5-valve sets from the 1960s. A few wrecked sets are a source of parts for some of the restoration work. I asked him what his favourite set was, to which he replied “I don’t have any particular favourite set”. However looking at the beautiful, lovingly restored Atwater Kent 20, it would be hard for me not to say that set would be my favourite, and from the photograph you can see why I might think that way. This model consists of five triode valves, with the first three as tuned stages with a separate control for each tuned circuit, plus two audio stages. I described one of its stablemates, the Atwater Kent 7-valve model 32, in the February 1999 issue of SILICON CHIP. Atwater Kent had progressed to single-knob tuning in this later set. I asked Jim if he had any particular theme in his collec­tion, to which he replied, “anything that comes along If you’re seriously into vintage radio you need a spacious workbench and a reasonable line-up of test equipment. Included here is a valve tester, RF generator and a vacuum tube voltmeter (VTVM). similar sets of the era and the larger the antenna connected to it, the better it will go. at the right price”. I gather from talking with Jim that he can sniff out a bargain at 100 paces. He said that it is a matter of keep­ing your eyes open for sets from various sources, such as antique and secondhand dealers, deceased estates, letting it be known around the area that you collect this “old junk, I’ll save you a trip to the tip”, etc, and horse-trading with other collectors. Auctions, he believes, are a dead loss, at least in his area. From the photographs it can be seen that the wooden cabinet sets in particular are extremely well restored and in some cases the cabinets have been made, which he really enjoys doing. One of Jim’s other hobbies is wood working and restoring old furniture, so no wonder the quality of restoration is so high. Cabinets are sometimes polished with French Polish but more commonly Mirror­ tone lacquer is used to finish them off. I asked Jim if he did all of the restoration of his sets, to which he replied Test equipment that he did most of it. He restores the cabinets and does the routine chassis clean ups, replacing valves and capacitors. The alignment of the IF stage(s), oscillator and RF stages he gets a mate to do. This attitude is a wise one. Don’t try and do something that isn’t your cup of tea. It’s so much better to get someone skilled in that area to do the job and maybe you can help that person with something they are not so good at. One particularly interesting set of Jim’s is a replica Rice Neutradyne. I asked Jim why he built this radio and he replied that he saw it in an early wireless magazine and decided he would like to build a replica. Most of the pieces came from the USA as he said the bits he wanted were generally cheaper and more readi­ly available over there than here. The Formica panel was obtained in Melbourne and the actual construction time was around two months. The unit performs on a par with Jim’s workbench can be seen in one of the photographs. It is not a particularly big bench but big enough for any restora­tion work on receiver chassis. It occupies an area towards one corner of what is really his woodworking centre. The instruments can be seen at the back of the bench, with the latest set being restored towards the front of the bench. Work on cabinets is done on a different bench within his rather large workshop. Jim has quite a useful range of test equipment and tools to aid in getting his collection up and going. Aside from the normal run of hand tools, he has a vice for small metal bashing jobs. The electronic test equipment consists of a test speaker, a vacuum tube voltmeter, a Leader LSG11 signal generator, analog and digital multi­ meters and a Calston 223A Valve Tester/Multimet­er. The test speaker is a handy device as it can substitute for the speaker October 1999  77 ston valve tester is in itself a vintage piece of test gear. It will test for valve emission and shorts and is particularly handy if no replacement valve is available when a set is being restored. Most restorers will not require more elaborate test gear than this, unless they are trying to find quite elusive faults. You can always ask a mate for some assistance under those circum­ stances. Spares are kept in small drawers and boxes and quite a reasonable supply of bits and pieces is on hand. Other activities To many collectors, an Atwater Kent receiver is the “holy grail”, as typified by this model 20 5-valve TRF set from the 1920s. Jim has other hobbies too, snooker being one of his main pastimes, and the snooker table and the vintage radio display share the one room. In addition to his wood working, CB radio and old gramophones hold his interest. I asked him how he repaired broken springs in wind-up gramophones to which he said he didn’t, as there was someone more skilled at the task in Adelaide. Cer­tainly the people with particular skills are spread far and wide. Sometime not too far in the future Jim can be expected to be heard on the amateur radio bands as a Novice Amateur Radio operator. He is busy doing a correspondence course on amateur radio with the Wireless Institute of Australia. His existing radio know­ledge along with what he is currently learning will soon make this a reality. Once Jim has his licence, his Yaesu FT101 amateur high frequency transceiver will be put to good use on transmit as well as receive. Good luck with your exams Jim. Insuring your collection Jim’s interest in vintage radio is wide ranging and his collection ranges from valve sets produced in the 1920s through to the 1960s. and speaker transformer in a set to find out what is going on in the audio output stage. The combination of the vacuum tube voltmeter, the analog multimeter and the digital multimeter allows testing various sections of a set at the same time and in assessing what is going on. I use short insulated leads with a small alligator clip on each end to connect the test probe of the meter 78  Silicon Chip to a specific part of the set I want to monitor. These can often be bought ready made up in a pack of several leads at some of the stores that cater for electronics buffs. The Leader LSG11 signal generator is ideal for doing align­ ments and generally sending signals through the set. These have been a very popular generator here in Australia. The Cal- An interesting point came out of the this visit with Jim Birtch­nell. He has taken photographs of his collection for insurance purposes and maybe many of us should do the same thing, particu­ larly where valuable items are concerned. Valuable pieces may need to be valued independently and placed on the insurance documents; something to think about. We don’t like to think that someone would want to steal our pride and joy but it could hap­pen, or maybe a fire could destroy your collection. My thanks to Jim for the opportunity to see and write about his collection and to talk about what collecting SC means to him. A comprehensive programmable touchscreen remote con­troller A huge variety of electronic equipment these days comes with an infrared remote control. From the everyday TV set, VCR and audio entertainment systems, remote controls are now used for projec­tion TV systems, pay TV, airconditioners, room lighting, cur­tains, burglar alarms and so on. By LEO SIMPSON JBL’s “Take Control” TC1000 I F YOU HAVE a component audio system, you are likely to have separate remote controls for the DVD or CD player, tape deck, tuner and so on. So much so that many homes may have five or six separate remote controls in the living room. In my own case, I have three remote control units in the family room just to watch TV plus several more in the lounge room where the main stereo system is. Thank goodness I don’t presently have it all combined in the one room, together with a home theatre system. That’s not to say that I won’t have this sort of setup in the future though. Clearly, most homes now have “remote control anarchy” and there are just too many remotes with teensy-weensy buttons, to many to keep stocked with batteries, too many to lose, drop or otherwise become unusable. What is the answer? No-one would suggest going back to the days when all entertainment equipment was solely controlled by knobs and switches on the front panels - perish the thought! There have also been some “learning remotes” which are intended to take over the functions of one or more remotes but there is a limit to how many multi-purpose buttons which can be fitted on to a remote control and how do you remember all the func­tions in any case! This problem has been growing for some time and now a new concept in remote controls has been introduced. Called the “Take Control” TC1000 (we hate the name but never mind) by JBL and Microsoft, it is quite different in approach. As shown in the photo, it has a large liquid crystal display (LCD) and just four buttons and a roller knob on its control panel. It is a fairly bulky but comfortable to hold in the hand October 1999  79 The Take Control Editor While you can do all the normal setup and programming of the TC1000 via its on-screen menus, you can also add considerable enhancements if you hook it up to your computer via a serial cable. This CD ROM is supplied with the unit and you can use it on any Windows 95/98/ NT system. Making the system work is easy – you just load the CD ROM and follow the on-screen prompts to add devices and to configure the controls. and quite heavy too, at 380 grams. Two buttons labelled + and - are there merely to control the audio volume on whatever equipment you are using. Then there are two buttons on the righthand side which provide back-lighting for the LCD screen and one to mute the sound, handy when those pesky commercials are on. On the lefthand side is the menu button. Pressing this brings up the opening screen on the TC1000 and then you can scroll up or down the display using the rolling selector to pick the function you want. Say you want to watch a video. You scroll to that bar and then press the selector to bring up another display with 10 buttons on screen. The TC1000 is now ready to control all the functions which may be involved: those of the VCR and TV plus the sound system if that is involved. For example, you can press Play, Rewind, Fast Forward, Pause, Stop and so on, just as you would with a normal VCR remote control. The on-screen display fades after a few seconds (the time is also programmable) so that the batteries are conserved. To bring it up again, just press anywhere on the screen and you can resume control as before. Naturally you can use the volume up, down and mute buttons at any time, without the need to touch the screen. Much the same approach applies if you want to watch TV. Rolling the Fig.1: the “Take Control Editor” launches when you load the CD-ROM. It provides an easy way of adding extra devices and customising the control layout. 80  Silicon Chip selector to “Watch TV” and pressing it brings up a 10-button screen so you can turn on the TV and select channels. Setting up the TC1000 is easy. In my case, I wanted to set it up to run a Philips TV, Sharp VCR and Jerrold Cable TV selec­tor. You just go to the Home menu, scroll to “Device Setup” and click it and then press “Add” on the Devices screen. You then scroll down the list and pick the one you want to add. In my case I wanted to add all three devices so I first of all picked “Cable Box”. You then scroll down through an astonishingly long list of more than 80 brands (fortunately they’re in alphabetical order). I selected Jerrold, and was told that there are eight different models to pick from. The TC1000 then leads you through a test procedure whereby you attempt to power up the cable box. When you finally do (in my case it was the seventh attempt) it informs you that you are now set up to control your Jerrold cable box. And lo and behold I was. I then went through the same procedure for VCRs. Would you believe it caters for 140 different brands of VCR and again, all the different models within each brand? By the time I had finished with the setup for the TV I was almost overcome with admiration for the amount of effort that must have gone into the development of this device. When I was finished I could control both the cable box and TV if I just wanted to watch TV and if I wanted to watch a tape, I could do the same. I know Fig.2: clicking the “Devices” option brings up this dialog. It shows the devices that have already been installed and lets you edit these and add new devices. Fig.3: to add a new device, you first select the device category as shown in this dialog. If the device isn’t listed, the TC1000 can learn from the existing controller. the average child would take to this device like a duck to water but I still find such things amazing. The fact that this device can store such a huge variety of codes made me go to the handbook to see how much memory it has. Alas it doesn’t say but it is non-volatile because it does not lose the settings if you remove the batteries. By the way, you can easily delete any device that you may have programmed in and if you have a device that is not included in the comprehensive lists, there is a procedure whereby the TC1000 will learn all the relevant codes. But wait, there’s more. While you can do all the normal setup and programming of the TC1000 via its on-screen menus, you can also add Fig.4: after you select the device brand, you disconnect the unit from the PC and follow the instructions on the TC1000’s display to complete the setup. considerable enhancements if you hook it up to your computer via a serial cable. The TC1000 comes with CD ROM and you can use it on any Windows 95/98/NT system. Making the system work is easy. You just insert the CD ROM and it comes up with a prompt screen to tell you how to connect the TC1000 to your PC’s serial port. It then finds it and asks whether you want to synchronise your TC1000. Clicking yes brings up another screen and it tells you it has found extra devices; in other words, the devices that are already programmed into the TC1000. You can then go through a number of screens to add or delete functions or customise in particular ways to suit your wants. Overall, as I have already indicat- Fig.5: once a device has been added, you can edit its control layout by adding or deleting buttons and by moving them to new locations on the activity screen. ed, this is a very impres­sive product, considering the huge amount of effort which must have gone into its development. Is it perfect? No. I would have liked better contrast on the LCD screen, particularly when you are using it in brightly lit rooms. It does have a contrast adjust procedure but I still found it a bit weak. On the other hand, the screen can be backlit so you can use it in dark rooms as well, which is not the case with the vast majority of remote controls. It works well in large rooms too, so it must have good infrared output. The price of the JBL “Take Control” TC1000, complete with CD-ROM and serial cable is $669. For further information, contact the Australian distributor for JBL, Convoy InternaSC tional. Phone 1 800 817 787. Fig.6: if it’s necessary for the TC1000 to learn from an existing remote control, the “Take Control Editor” takes you through the procedure step by step. October 1999  81 YZ TABLE WITH STEPPER MOTOR CONTROL Part.6: Pen Holder & Plotting Procedure We hope you didn’t break any drills playing around with the XYZ table and the software last month. In this final article, we describe the pen holder and the plotting software. By RICK WALTERS While it may seem a bit back-tofront to have presented the article to drill a PC board before running one to plot it, the reason is quite simple. It was a much easier task for us to develop the drilling project rather than the plotting one. This month, plot it we shall. But before talking about plotting, we need to briefly discuss pens and the pen holder. One of the major problems with plotting is finding a suitable pen which will draw satisfactorily on the copper laminate. Also the ink in the pen must be waterproof to allow it to stand up to the etching process. Once we have found the pen, we need to be able to clamp it securely to ensure consistent relocation each time we fit it. The diagram of Fig.1 shows how the pen holder was made. The top lip and turned body fit neatly into the plastic drill clamps and ensure consistent location and positioning of the pen. If you use a different brand of drill stand you will quite likely have to Extract from PCBDRAW.BAS 5570 5580 5590 5600 5610 WHILE NOT EOF(2) INPUT# 2,X$,Y$ XNEW = VAL(X$): YNEW = VAL(Y$) IF RIGHT$(X$,1) < “:” THEN 5630 ‘not P (U or D) IF RIGHT$(X$,2) = “PU” THEN GOSUB 7230 ELSE IF RIGHT$(X$,2) = “PD” THE GOSUB 7130 5620 DPEN = RIGHT$(X$,2) ‘store new value 5630 WHILE XNEW <> XOLD OR YNEW <> YOLD: GOSUB 3030: WEND ’move to new X & Y position 5640 WEND 82  Silicon Chip modify the holder shape to fit your clamps. Our prototype was turned up in mild steel while the threaded insert was in brass. Software The software files we need for plotting the PC board are as follows: PCBDRAW.BAS, PCBDRAW.EXE, DRWSETUP.BAS, DRWSETUP.EXE, DRWSETUP.FIL, PENTEST.BAS and PENTEST.EXE. You will see that they follow a similar sequence to those supplied in the July issue which allowed you to drill the PC board. The first two are the programs that actually draw the PC tracks and these will be described shortly. The next two are the setup files which allow you to set the maximum X and Y co-ordinates, the motor stepping rate, the XY card address, the Z card address, the fast and slow pen down positions and select the parallel port you wish to use. All the values except for the fast and slow pen will be the same as you used in the DRLSETUP program. DRWSETUP.FIL is the file which stores these parameters and it is accessed by both PCBDRAW. BAS and PCBDRAW.EXE. The PENTEST programs work in the same manner as the DRLTEST programs described previously, allowing you to set the distance the pen sits above the PC board when it is not drawing and the amount of pressure it applies to the copper while it is actually drawing. It will most likely take you a couple of attempts to get these positions just right. Again, as with PCBDRILL, PCB­ DRAW lets Protel do most of the hard work. We use the values in the plotter file, generated by Protel, to move to the X and Y co-ordinates, then the pen up and pen down instructions to control the Z-axis motor. A small PC board called TRACKS.PCB, which consisted of a number of tracks of increasing thickness from 10 to 60 thou, was laid out as a test board then Protel was used to generate the plot file called TRACKS.PBL. This text file is listed in Table 1. Plotter file We elected to use the Roland GL1 plotter file as this plotter was the one we used at SILICON CHIP and our copy of Protel was set up for this device. After the preamble the first significant entry is PU102,102; ie, pen up then move to X102,Y102. The next entry PD102,203; says draw (pen down) a line from X102 to Y203 and so on. This line is the vertical corner mark. The pen point thickness is given to Protel as part of the setup procedure and if you trace the next few values you will see that the pen (12 thou) draws another vertical line then a diagonal line, moves in a 5 thou arc and redraws the line, ie, the track is 17 thou wide. Actually, it should be 20 thou but who’s going to argue about 3 thou? Protel suggest that you experiment with the pen width setting until you find the best value for the particular pen you are using. They actually recommend using 13 thou for a 0.3mm (11.8 thou) pen. The program continues to read through the file, lifting and lowering the pen until it finds the entry SP0; at which time it has reached the end of the useful data, so the program terminates. Creating a temporary file That is the big picture but as the saying goes, the devil is in the detail. To make things easier for the software we first open a new file called PCBDRAW.TMP, then search through the PBL file until we locate SP1;. We then move PU from the beginning of the X entry to the end; ie 102PU, then save 102PU,102 in the new file. At the same time we store the X and Y values in XBIG and YBIG. Each entry is changed in a similar manner and written to the new file. Fig.1: the pen holder details. The top lip and turned body fit neatly into the plastic drill clamps and ensure consistent location and positioning of the pen. The prototype was turned up in mild steel while the threaded insert was in brass. If the new X or Y value is bigger than the saved BIG value then it replaces that value. At the end of this subroutine if the XBIG or YBIG value exceeds the value you have allocated to the X maximum or Y maximum values in the setup program the PCBDRAW program will terminate, writing an error message on the screen indicating an out of limits condition. Assuming there is no error message the pen will then move to the fast down position, the software will read the first entry in the TMP file and (in this case) the table will move to 102,102. Why rewrite the file you may ask? There are two reasons; the first is because we had to read through the file anyway to find the maximum X and Y values. The second is because the value of PU102 in Basic is zero, but the value of 102PU is 102. Thus it is a little quicker to compute the next X and Y values and with older machines we need to save as much time as we can, although in the long run the time taken by the X and Y mechanical movements will be the limiting factor. Plotting The X and Y co-ordinates will be read and the pen moved up and down until the end of the file is reached. The computer’s speaker will then beep to alert you to this fact, the message “Drawing completed. Homing table.” will be displayed and the table will return to 0,0. The motors will then be de-energised and the TMP file will be deleted before the program closes. As with the drilling program, if any keyboard key is pressed while the program is running, the computer’s speaker will beep to acknowledge the keypress, a message to this effect will be printed at the bottom of the screen, then the pen will home and the program will terminate. If you look at the Basic listing (from October 1999  83 The photograph above shows how the pen holder goes together (note that the spring that fits over the ink reservoir is missing), while at right is the completely assembled unit. The unit is secured by the plastic drill clamps but if you use a different brand of drill stand to ours, you may have to modify the holder shape to fit your clamps. our web site or on the floppy we can supply), you will see that a lot of the code is identical or very similar to PCBDRILL. The initialisation, opening screen, X and Y axis movement, pen control and file code are identical. The plot file (PBL) structure is different to the text (TXT) file used in the drilling program and it needs different software to process it. Subroutine 5000 does this. You will note that on line 5550 we use DPEN to keep track of the pen position. PEN is a reserved word in GW Basic, and if you look at line 1030 you will see we defined words starting with D as strings, thus DPEN allows us to keep track of PU and PD (pen up and pen down) commands. So all we have to do is read through the file, moving to the X and Y positions as dictated by the file values and take the pen up or down. This is done in lines 5570 to 5640 (see panel at start of article). The software keeps looping through the six lines 5580 to 5630 until the end of the file is reached, then the program terminates as explained previously. First PC board The first PC board we plotted and drilled is shown in the accompanying photo. All the plotting and drilling defects are due to the excessive backlash in the drillstand mechanism, not the XY table. It is not a huge amount but by the time it reaches the pen tip or drill point it can be quite a few thou. Hopefully, your drill stand mech­ anism is better in this regard than the one we used. Normally, the PC board is etched before it is drilled and during the drilling process the drill tip wanders to the pad centre which has been etched away. In the present setup, the drill tip will have no guide to the pad centre and can wander a little in any direction before beginning to make the hole. We had about 25mm of the 0.8mm drill protruding from the drill chuck and this contributed to the problem. A shorter length would probably have helped. More on pens This photo shows the test PC board that we plotted and drilled. Note that the plotting and drilling defects are due to the excessive backlash in the drill stand mechanism that we used, not the XYZ table. 84  Silicon Chip Back to the pen: the only pen we found to be really usable with our Roland plotter was a refillable type, which was quite messy to use, as the ink had to be washed out and the pen cleaned thoroughly each time a plot was done. The ink is a waterproof type which comes in 22ml bottles but a bottle this size is sufficient for a great number of plots. To our disappointment, this pen proved to be unsuitable for the XYZ table as the writing speed was too slow, causing the ink to flow into blobs whenever a pad was drawn. Even when plotting long tracks the ink tended to puddle. The plot in the photograph was done with a Pentel type CVP 0.35mm tip pen. The ink in this pen is not waterproof but the photo gives an indication of the result you can expect. We are led to believe that the Pentel type CPF, which is used to plot on film, contains a waterproof ink so we are chasing one at the moment. We will publish the outcome as soon as we get hold of it and can test it. Setting up plot files Just as we set up Protel to generate drill files last month, this time we have to set it up to create the correct plot files for drawing. You did most of the difficult work last month setting up the directories. All we need to do now is to allocate the correct plotter driver to create files that can be read by our software. Load TRAXPLOT or EASYPLOT, move down to SETUP (press Enter) and move down to PLOTTER (press Enter). The type of plotter we need is ROLAND RD-GL 1. If there is a different type press Enter and either you will be presented with a list of plotters or asked for a path to where you have saved the plot files. Move down to the correct one then press Enter again. Move down to DEVICE and press Enter. Move right down to FILE and press Enter once more. If you have loaded a file it should then read DEVICE C:<at>Filename. We’re nearly there now. Move down to OPTIONS (Enter) and if type of plot reads BOTTOM LAYER you are set otherwise press Enter and select it. Lastly, move down to FLIP LAYER SETUP and ensure that they all show normal. Pressing Enter will toggle the entry. Right, all done, now keep pressing Escape until you get back to the FILE menu from whence you can exit the program. To generate a plot file you must first load TRAXPLOT then a file, move Table 1: Protel Tracks.pbl Test Plot File ∧[.<at>; 1:IN; SP; VS10; SP1; PU102,102; PD102,203; PU203,203; PD203,381,200,384,353,536,357,537,360,534,358,531,206,378, 202,377,199,380,200,384,203,381,356,533,356,540,635,540,640, 538,642,533,640,529,635,527,356,527,351,529,349,533,351,538, 356,540,356,533,635,533,641,540,819,362,822,358,822,353,819, 349,815,347,810,347,806,349,629,527,626,531,626,536,629,540, 633,542,637,542,641,540,637,536,815,358,811,353,633,531,637, 536,635,533,813,356,827,356,827,152,826,148,824,143,820,140, 815,138,810,138,806,140,802,143,799,148,799,152,799,356,799, 360,802,365,806,368,810,370,815,370,820,368,824,365,826,360, 827,356,818,356,818,152,807,152,807,356,818,356,813,356,813, 152,813,133,559,133,554,134,549,136,545,139,542,143,540,147, 539,152,540,157,542,162,545,166,549,169,554,171,559,172,813, 172,818,171,822,169,826,166,830,162,831,157,832,152,831,147, 830,143,826,139,822,136,818,134,813,133,813,142,559,142,548, 152,559,163,813,163,824,152,813,142,813,150,559,150,559,155, 813,155,813,150,813,152,559,152,542,135,364,313,361,317,358, 321,357,326,357,331,357,337,359,341,362,346,366,349,370,352, 375,354,380,355,385,354,390,353,394,351,398,347,576,170,579, 166,582,161,583,156,583,151,582,146,581,141,578,137,574,133, 570,131,565,129,560,128,555,128,550,130,546,132,542,135,546, 139,368,317,363,335,376,348,394,343,572,165,577,148,564,135, 546,139,550,144,372,321,372,339,390,339,568,161,568,144,550, 144,554,148,377,326,385,335,563,157,554,148,559,152,381,330, 559,153,559,152,381,330; PU203,102; PD102,102; PU102,508; PD102,610,203,610; PU914,610; PD1016,610,1016,508; PU1016,203; PD1016,102,914,102; SP0; SP; IN; down to PLOT, then confirm YES to CONFIRM PROCEED WITH PLOT. The message “PLOT FILE GENERATED C:<at>FILENAME.PBL Press any key to continue” will display, and upon pressing a key you will be returned to the FILE menu from whence you can exit. Running PCBDRAW will now find the PBL file and draw it. Well that wraps up this series. We hope those of you who were interested in the project will give us some feedback on your successes or otherwise and any problems you might have experienced. Free EasyTrax software The EasyTrax software is available FREE from the Protel web site (ie, protel.com.au). But note that they will not provide any support for it; you are on your own! However, after you play around with it for a while you will find it rather easy to use, as the drop down menus guide you through SC each step. October 1999  85 TECHNICAL LOOK: TEN NEW NEW! TCP/IP EXPLAINED By Philip Miller. Published 1997. $ 90 This concise and practical book offers readers an in-depth understanding of the Internet Protocol suite. It assumes no prior knowledge of TCP/IP, only a basic understanding of LAN access protocols, explaining all the elements and alternatives. It leads the reader through the Internet protocols, combining study questions with reference material. Examples of network designs and implementations are given. 518 pages, in paperback, at $90.00. LOCAL AREA NETWORKS: An Introduction to the Technology NEW! SETTING UP A WEB SERVER A complete reference for anyone setting up a web server. Covers all major platforms, soft­ ware, links and web techniques. It details each step required to choose, install and configure the hardware and software elements, create an effective site and promote it successfully. The book covers the main web server software applications, how they differ, and which work best in each environment. 273 pages, in paperback, at $65.00. NEW! 65 NEW! By Tim Williams. First published 1991 (reprinted 1997). THE CIRCUIT DESIGNER’S COMPANION By PK McBride & Nat McBride. Published 1999. $ O R D E R H E R E 29 95 If you want to create web pages for your business or your own home site, but don't know where to start . . . or if you have some experience of Web page design and now need to master all aspects of HTML form then “HTML4.0 Made Simple” is for you. it uses a combination of tutorial approach, carefully focussed examples and quick reference guides. 198 pages, in paperback, at $29.95.      TCP/IP EXPLAINED.............................................$90.00  LOCAL AREA NETWORKS..................................$65.00  HTML 4.0 MADE SIMPLE...................................$29.95  SETTING UP A WEB SERVER.............................$65.00  THE CIRCUIT DESIGNER’S COMPANION...........$59.95  ELECTRIC MOTORS AND DRIVES......................$59.95  UNDERSTANDING TELEPHONE ELECTRONICS....$55.00  AUDIO ELECTRONICS........................................$79.00  GUIDE TO TV & VIDEO TECHNOLOGY...............$55.00  EMC FOR PRODUCT DESIGNERS.......................$95.00  THE ART OF LINEAR ELECTRONICS..................$80.00  INTERNET HOME PAGES MADE SIMPLE...........$24.95  DIGITAL ELECTRONICS .....................................$59.95  ESSENTIAL LINUX..............................................$85.00               ORDER TOTAL: $............. 86  Silicon Chip Includes grounding, printed circuit design and layout, the characteristics of practical active and passive components, cables, linear ICs, logic circuits and their interfaces, power supplies, electromagnetic compatibility, safety and thermal management. Aimed at the practising designer who needs straight­ forward, easy-to-follow advice. 302 pages, in paperback, at $59.95. $ HTML 4.0 MADE SIMPLE 65 $ By John E. McNamara. 2nd edition 1996. Intended for those who want to become more familiar with local area networks (LANs) without facing the challenge of a 400-page text. The goals of the book are to give prospective LAN users or purchasers familiarity with the concepts involved and to provide a head start for reading more detailed texts. 191 pages, in paperback, at $65.00. NEW! By Simon Collin. Published 1997. $ 59 95 ELECTRIC MOTORS AND DRIVES NEW! By Austin Hughes. Second edition published 1993 (reprinted 1997). This book is for non-specialist users of electric motors and drives. The author explores most of the widely-used modern types of motor and drive, including conventional and brushless DC, induction motors (mains and inverter-fed), stepping motors, synchronous motors (mains and converter-fed) and reluctance motors. 339 pages, in paperback, at $59.95. 59 95 $ Your Name_________________________________________________ PLEASE PRINT Address ___________________________________________________ ___________________________________ Postcode_______________ Daytime Phone No. (______) __________________________________ STD  Cheque/Money Order enclosed OR  Charge my credit card –  Bankcard   Visa Card   MasterCard Signature_________________________ Card expiry date______/______ PLUS P&P (if applic): $.............. TOTAL$ AU.................... ALL TITLES SUBJECT TO AVAILABILITY. PRICES VALID FOR MONTH OF MAGAZINE ISSUE ONLY. BOOKSHOP WANT TO SAVE 10%? SILICON CHIP SUBSCRIBERS AUTOMATICALLY QUALIFY FOR A 10% DISCOUNT ON ALL PURCHASES! TITLES AVAILABLE! $ UNDERSTANDING TELEPHONE ELECTRONICS By Stephen J. Bigelow. Third edition published 1997 by Butterworth-Heinemann. 55 (To subscribe, see page 53) A very useful text for anyone wanting to become familiar with the basics of telephone technology. The 10 chapters explore telephone fundamentals, speech signal processing, telephone line interfacing, tone and pulse generation, ringers, digital transmission tech­ niques (modems & fax machines) and much more. Ideal for students. 367 pages, in soft cover at $55.00. AUDIO ELECTRONICS   GUIDE TO TV & VIDEO TECHNOLOGY $ By John Linsley Hood. First published 1993. NEW SECOND EDITION 1998. 80 All you need to get started. Create and design your own Internet home pages that include both text and graphics, using this practical, easy to follow, jargon free guide. This edition has been enhanced and updated and now covers HTML 4.0. 182 pages, in paperback, at $24.95. 79 $ Eugene Trundle has written for many years in Television magazine and his latest book is right up to date on TV and video technology. The book includes both theory and practical servicing information and is ideal for both students and technicians. 382 pages, in paperback, at $55.00. 55 EMC FOR PRODUCT DESIGNERS NEW! P&P Add $A5.00 per book – Orders over $100 P&P free in Australia. NZ: Add $A10 per book, $A15 elsewhere 24 95 $ DIGITAL ELECTRONICS –  A PRACTICAL APPROACH By Richard Monk. Published 1998. $ 59 95 With this book you can learn the principles and practice of digital electronics without leaving your desk, through the popular simulation applications, EASY-PC Pro XM and Pulsar. Alternatively, if you want to discover the applications through a thoroughly practical exploration of digital electronics, this is the book for you. A free floppy disk is included, featuring limited function versions of EASY-PC Professional XM and Pulsar. 249 pages, in paperback, at $59.95. ESSENTIAL LINUX By Steve Heath. Published 1997. By Tim Williams. First pub­­lished 1992. Second edition 1996. Widely regarded as the standard text on EMC, this book provides all the information necessary to meet the requirements of the EMC Directive. It includes chapters on standards, measurement techniques and design principles, including layout and grounding, digital and analog circuit design, filtering and shielding and interference sources. The four appendices give a design checklist and include useful tables, data and formulae. 299 pages, in soft cover at $95.00. NEW! By Lilian Hobbs. First published 1996. Second edition 1999. By Eugene Trundle. First pub­­lished 1988. Second edition 1996. $ This practical handbook from one of the world’s most prolific audio designers has been updated and amended to make it the leading practical source of information for those interested in linear electronics and its applications, particularly in the world of audio design. 348 pages, in paperback, at $80.00. DESIGNING INTERNET HOME PAGES MADE SIMPLE By John Linsley Hood. First published 1995. Second edition 1999. This book is for anyone involved in designing, adapting and using analog and digital audio equipment. It covers tape recording, tuners and radio receivers, preamplifiers, voltage amplifiers, audio power amplifiers, compact disc technology and digital audio, test and measurement, loudspeaker crossover systems, power supplies and noise reduction systems. 375 pages in soft cover at $79.00. THE ART OF LINEAR ELECTRONICS NEW! 95 $ Provides all the information and software that is necessary for a PC user to install and use the freeware Linux operating system. It details, setp-by-step, how to obtain and configure the operating system and utilities. It also explains all of the key commands. The text is generously illustrated with screen shots and examples that show how the commands work. Includes a CD-ROM containing Linux version 1.3 and including all the interim updates, basic utilities and compilers with their associated documen­ tation. 257 pages, in paperback, at $85.00. 85 $ NEW! POST TO: SILICON CHIP Publications, PO Box 139, Collaroy NSW, Australia 2097. OR CALL (02) 9979 5644 & quote your credit card details; or FAX TO (02) 9979 6503 DO ecember ctober 1999  87 Silicon Chip Back Issues September 1988: Hands-Free Speakerphone; Electronic Fish Bite Detector; High Performance AC Millivoltmeter, Pt.2; Build The Vader Voice. April 1989: Auxiliary Brake Light Flasher; What You Need to Know About Capacitors; 32-Band Graphic Equaliser, Pt.2; The Story Of Amtrak Passenger Services. May 1989: Build A Synthesised Tom-Tom; Biofeedback Monitor For Your PC; Simple Stub Filter For Suppressing TV Interference; The Burlington Northern Railroad. July 1989: Exhaust Gas Monitor; Experimental Mains Hum Sniffers; Compact Ultrasonic Car Alarm; The NSW 86 Class Electrics. September 1989: 2-Chip Portable AM Stereo Radio (Uses MC13024 and TX7376P) Pt.1; High Or Low Fluid Level Detector; Studio Series 20-Band Stereo Equaliser, Pt.2. October 1989: FM Radio Intercom For Motorbikes Pt.1; GaAsFet Preamplifier For Amateur TV; 2-Chip Portable AM Stereo Radio, Pt.2; A Look At Australian Monorails. November 1989: Radfax Decoder For Your PC (Displays Fax, RTTY & Morse); FM Radio Intercom For Motorbikes, Pt.2; 2-Chip Portable AM Stereo Radio, Pt.3; Floppy Disc Drive Formats & Options; The Pilbara Iron Ore Railways. January 1990: High Quality Sine/Square Oscillator; Service Tips For Your VCR; Phone Patch For Radio Amateurs; Active Antenna Kit; Designing UHF Transmitter Stages. February 1990: A 16-Channel Mixing Desk; Build A High Quality Audio Oscillator, Pt.2; The Incredible Hot Canaries; Random Wire Antenna Tuner For 6 Metres; Phone Patch For Radio Amateurs, Pt.2. March 1990: Delay Unit For Automatic Antennas; Workout Timer For Aerobics Classes; 16-Channel Mixing Desk, Pt.2; Using The UC3906 SLA Battery Charger IC; The Australian VFT Project. April 1990: Dual Tracking ±50V Power Supply; Voice-Operated Switch (VOX) With Delayed Audio; 16-Channel Mixing Desk, Pt.3; Active CW Filter; Servicing Your Microwave Oven. June 1990: Multi-Sector Home Burglar Alarm; Build A Low-Noise Universal Stereo Preamplifier; Load Protector For Power Supplies; Speed Alarm For Your Car. July 1990: Digital Sine/Square Generator, Pt.1 (covers 0-500kHz); Burglar Alarm Keypad & Combination Lock; Build A Simple Elec­ tronic Die; A Low-Cost Dual Power Supply; Inside A Coal Burning Power Station. August 1990: High Stability UHF Remote Transmitter; Universal Safety Timer For Mains Appliances (9 Minutes); Horace The Electronic Cricket; Digital Sine/Square Generator, Pt.2. September 1990: A Low-Cost 3-Digit Counter Module; Build A Simple Shortwave Converter For The 2-Metre Band; The Bose Lifestyle Music System (Review); The Care & Feeding Of Nicad Battery Packs (Getting The Most From Nicad Batteries). October 1990: The Dangers of PCBs; Low-Cost Siren For Burglar Alarms; Dimming Controls For The Discolight; Surfsound Simulator; DC Offset For DMMs; NE602 Converter Circuits. March 1992: TV Transmitter For VHF VCRs; Thermostatic Switch For Car Radiator Fans; Coping With Damaged Computer Directories; Guide Valve Substitution In Vintage Radios. April 1992: IR Remote Control For Model Railroads; Differential Input Buffer For CROs; Understanding Computer Memory; Aligning Vintage Radio Receivers, Pt.1. May 1992: Build A Telephone Intercom; Electronic Doorbell; Battery Eliminator For Personal Players; Infrared Remote Control For Model Railroads, Pt.2; Aligning Vintage Radio Receivers, Pt.2. November 1990: How To Connect Two TV Sets To One VCR; Build An Egg Timer; Low-Cost Model Train Controller; 1.5V To 9V DC Converter; Introduction To Digital Electronics; Build A Simple 6-Metre Amateur Band Transmitter. December 1990: The CD Green Pen Controversy; 100W DC-DC Converter For Car Amplifiers; Wiper Pulser For Rear Windows; 4-Digit Combination Lock; 5W Power Amplifier For The 6-Metre Amateur Transmitter; Index To Volume 3. January 1991: Fast Charger For Nicad Batteries, Pt.1; Have Fun With The Fruit Machine; Two-Tone Alarm Module; LCD Readout For The Capacitance Meter; How Quartz Crystals Work; The Dangers of Servicing Microwave Ovens. February 1991: Synthesised Stereo AM Tuner, Pt.1; Three Low-Cost Inverters For Fluorescent Lights; Low-Cost Sinewave Oscillator; Fast Charger For Nicad Batteries, Pt.2; How To Design Amplifier Output Stages. March 1991: Remote Controller For Garage Doors, Pt.1; Transistor Beta Tester Mk.2; A Synthesised AM Stereo Tuner, Pt.2; Multi-Purpose I/O Board For PC-Compatibles; Universal Wideband RF Preamplifier For Amateur Radio & TV. April 1991: Steam Sound Simulator For Model Railroads; Remote Controller For Garage Doors, Pt.2; Simple 12/24V Light Chaser; Synthesised AM Stereo Tuner, Pt.3; A Practical Approach To Amplifier Design, Pt.2. May 1991: 13.5V 25A Power Supply For Transceivers; Stereo Audio Expander; Fluorescent Light Simulator For Model Rail­ ways; How To Install Multiple TV Outlets, Pt.1. June 1991: A Corner Reflector Antenna For UHF TV; Build A 4-Channel Lighting Desk, Pt.1; 13.5V 25A Power Supply For Transceivers, Pt.2; Active Filter For CW Reception; Tuning In To Satellite TV, Pt.1. July 1991: Loudspeaker Protector For Stereo Amplifiers; 4-Channel Lighting Desk, Pt.2; How To Install Multiple TV Outlets, Pt.2; Tuning In To Satellite TV, Pt.2. September 1991: Digital Altimeter For Gliders & Ultralights; Ultrasonic Switch For Mains Appliances; The Basics Of A/D & D/A Conversion; Plotting The Course Of Thunderstorms. October 1991: Build A Talking Voltmeter For Your PC, Pt.1; SteamSound Simulator For Model Railways Mk.II; Magnetic Field Strength Meter; Digital Altimeter For Gliders, Pt.2; Military Applications Of R/C Aircraft. November 1991: Build A Colour TV Pattern Generator, Pt.1; A Junkbox 2-Valve Receiver; Flashing Alarm Light For Cars; Digital Altimeter For Gliders, Pt.3; Build A Talking Voltmeter For Your PC, Pt.2; Build a Turnstile Antenna For Weather Satellite Reception. June 1992: Multi-Station Headset Intercom, Pt.1; Video Switcher For Camcorders & VCRs; IR Remote Control For Model Railroads, Pt.3; 15-Watt 12-240V Inverter; A Look At Hard Disc Drives. August 1992: Automatic SLA Battery Charger; Miniature 1.5V To 9V DC Converter; 1kW Dummy Load Box For Audio Amplifiers; Troubleshooting Vintage Radio Receivers; The MIDI Interface Explained. October 1992: 2kW 24VDC - 240VAC Sinewave Inverter; Multi-Sector Home Burglar Alarm, Pt.2; Mini Amplifier For Personal Stereos; A Regulated Lead-Acid Battery Charger. January 1993: Flea-Power AM Radio Transmitter; High Intensity LED Flasher For Bicycles; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.4; Speed Controller For Electric Models, Pt.3. February 1993: Three Projects For Model Railroads; Low Fuel Indicator For Cars; Audio Level/VU Meter (LED Readout); An Electronic Cockroach; 2kW 24VDC To 240VAC Sinewave Inverter, Pt.5. March 1993: Solar Charger For 12V Batteries; Alarm-Triggered Security Camera; Reaction Trainer; Audio Mixer for Camcorders; A 24-Hour Sidereal Clock For Astronomers. April 1993: Solar-Powered Electric Fence; Audio Power Meter; Three-Function Home Weather Station; 12VDC To 70VDC Converter; Digital Clock With Battery Back-Up. May 1993: Nicad Cell Discharger; Build The Woofer Stopper; Alphanu­ meric LCD Demonstration Board; The Story of Aluminium. June 1993: AM Radio Trainer, Pt.1; Remote Control For The Woofer Stop­ per; Digital Voltmeter For Cars; Build A Windows-Based Logic Analyser. July 1993: Single Chip Message Recorder; Light Beam Relay Extender; AM Radio Trainer, Pt.2; Quiz Game Adjudicator; Win­ dows-Based Logic Analyser, Pt.2; Antenna Tuners – Why They Are Useful. August 1993: Low-Cost Colour Video Fader; 60-LED Brake Light Array; Microprocessor-Based Sidereal Clock; Southern Cross Z80-Based Computer; A Look At Satellites & Their Orbits. September 1993: Automatic Nicad Battery Charger/Discharger; Stereo Preamplifier With IR Remote Control, Pt.1; In-Circuit Transistor Tester; +5V to ±15V DC Converter; Remote-Controlled Cockroach. October 1993: Courtesy Light Switch-Off Timer For Cars; Wireless Microphone For Musicians; Stereo Preamplifier With IR Remote Control, Pt.2; Electronic Engine Management, Pt.1. November 1993: High Efficiency Inverter For Fluorescent Tubes; Stereo Preamplifier With IR Remote Control, Pt.3; Siren Sound Generator; Engine Management, Pt.2; Experiments For Games Cards. December 1993: Remote Controller For Garage Doors; Build A LED Stroboscope; Build A 25W Audio Amplifier Module; A 1-Chip Melody Generator; Engine Management, Pt.3; Index To Volume 6. December 1991: TV Transmitter For VCRs With UHF Modulators; Infrared Light Beam Relay; Colour TV Pattern Generator, Pt.2; Index To Volume 4. January 1994: 3A 40V Adjustable Power Supply; Switching Regulator For Solar Panels; Printer Status Indicator; Mini Drill Speed Controller; Stepper Motor Controller; Active Filter Design; Engine Management, Pt.4. January 1992: 4-Channel Guitar Mixer; Adjustable 0-45V 8A Power Supply, Pt.1; Baby Room Monitor/FM Transmitter; Experiments For Your Games Card. February 1994: Build A 90-Second Message Recorder; 12-240VAC 200W Inverter; 0.5W Audio Amplifier; 3A 40V Adjustable Power Supply; Engine Management, Pt.5; Airbags In Cars – A Look At How They Work. ORDER FORM Please send me the following back issues: _____________________________________________________________________ _______________________________________________________________________________________________________________ Card No. Signature ___________________________ Card expiry date_____ /______ Name ______________________________ Phone No (___) ____________ Note: all prices include post & packing Australia ....................................................... $A7 NZ & PNG (airmail) ...................................... $A8 Overseas (airmail) ...................................... $A10 Street ______________________________________________________ Detach and mail to: Silicon Chip Publications, PO Box 139, Collaroy, NSW, Australia 2097. Suburb/town _______________________________ Postcode ___________ Or call (02) 9979 5644 & quote your credit card details or fax the details to (02) 9979 6503. PLEASE PRINT 88  Silicon Chip ✂ Enclosed is my cheque/money order for $­______or please debit my:  ❏ Bankcard  ❏ Visa Card  ❏ Master Card March 1994: Intelligent IR Remote Controller; 50W (LM3876) Audio Amplifier Module; Level Crossing Detector For Model Railways; Voice Activated Switch For FM Microphones; Simple LED Chaser; Engine Management, Pt.6. March 1996: Programmable Electronic Ignition System; Zener Diode Tester For DMMs; Automatic Level Control For PA Systems; 20ms Delay For Surround Sound Decoders; Multi-Channel Radio Control Transmitter; Pt.2; Cathode Ray Oscilloscopes, Pt.1. April 1994: Sound & Lights For Model Railway Level Crossings; Dis­ crete Dual Supply Voltage Regulator; Universal Stereo Preamplifier; Digital Water Tank Gauge; Engine Management, Pt.7. April 1996: Cheap Battery Refills For Mobile Telephones; 125W Audio Power Amplifier Module; Knock Indicator For Leaded Petrol Engines; Multi-Channel Radio Control Transmitter; Pt.3; Cathode Ray Oscillo­ scopes, Pt.2. May 1994: Fast Charger For Nicad Batteries; Induction Balance Metal Locator; Multi-Channel Infrared Remote Control; Dual Electronic Dice; Simple Servo Driver Circuits; Engine Management, Pt.8. June 1994: 200W/350W Mosfet Amplifier Module; A Coolant Level Alarm For Your Car; 80-Metre AM/CW Transmitter For Amateurs; Converting Phono Inputs To Line Inputs; PC-Based Nicad Battery Monitor; Engine Management, Pt.9. May 1996: Upgrading The CPU In Your PC; High Voltage Insulation Tester; Knightrider Bi-Directional LED Chaser; Simple Duplex Intercom Using Fibre Optic Cable; Cathode Ray Oscilloscopes, Pt.3. June 1996: BassBox CAD Loudspeaker Software Reviewed; Stereo Simulator (uses delay chip); Rope Light Chaser; Low Ohms Tester For Your DMM; Automatic 10A Battery Charger. July 1994: Build A 4-Bay Bow-Tie UHF Antenna; PreChamp 2-Transistor Preamplifier; Steam Train Whistle & Diesel Horn Simulator; Portable 6V SLA Battery Charger; Electronic Engine Management, Pt.10. July 1996: Installing a Dual Boot Windows System On Your PC; Build A VGA Digital Oscilloscope, Pt.1; Remote Control Extender For VCRs; 2A SLA Battery Charger; 3-Band Parametric Equaliser; Single Channel 8-bit Data Logger. August 1994: High-Power Dimmer For Incandescent Lights; Microprocessor-Controlled Morse Keyer; Dual Diversity Tuner For FM Microphones, Pt.1; Nicad Zapper; Engine Management, Pt.11. August 1996: Electronics on the Internet; Customising the Windows Desktop; Introduction to IGBTs; Electronic Starter For Fluores­cent Lamps; VGA Oscilloscope, Pt.2; 350W Amplifier Module; Masthead Amplifier For TV & FM; Cathode Ray Oscilloscopes, Pt.4. September 1994: Automatic Discharger For Nicad Battery Packs; MiniVox Voice Operated Relay; Image Intensified Night Viewer; AM Radio For Weather Beacons; Dual Diversity Tuner For FM Microphones, Pt.2; Engine Management, Pt.12. October 1994: How Dolby Surround Sound Works; Dual Rail Variable Power Supply; Build A Talking Headlight Reminder; Electronic Ballast For Fluorescent Lights; Build A Temperature Controlled Soldering Station; Electronic Engine Management, Pt.13. November 1994: Dry Cell Battery Rejuvenator; Novel Alphanumeric Clock; 80-Metre DSB Amateur Transmitter; Twin-Cell Nicad Dis­ charger (See May 1993); How To Plot Patterns Direct to PC Boards. December 1994: Dolby Pro-Logic Surround Sound Decoder, Pt.1; Easy-To-Build Car Burglar Alarm; Three-Spot Low Distortion Sinewave Oscillator; Clifford – A Pesky Electronic Cricket; Remote Control System for Models, Pt.1; Index to Vol.7. January 1995: Sun Tracker For Solar Panels; Battery Saver For Torches; Dolby Pro-Logic Surround Sound Decoder, Pt.2; Dual Channel UHF Remote Control; Stereo Microphone Pre­amp­lifier. February 1995: 50-Watt/Channel Stereo Amplifier Module; Digital Effects Unit For Musicians; 6-Channel Thermometer With LCD Readout; Wide Range Electrostatic Loudspeakers, Pt.1; Oil Change Timer For Cars; Remote Control System For Models, Pt.2. March 1995: 50 Watt Per Channel Stereo Amplifier, Pt.1; Subcarrier Decoder For FM Receivers; Wide Range Electrostatic Loudspeakers, Pt.2; IR Illuminator For CCD Cameras; Remote Control System For Models, Pt.3; Simple CW Filter. April 1995: FM Radio Trainer, Pt.1; Photographic Timer For Dark­ rooms; Balanced Microphone Preamp. & Line Filter; 50W/Channel Stereo Amplifier, Pt.2; Wide Range Electrostatic Loudspeakers, Pt.3; 8-Channel Decoder For Radio Remote Control. May 1995: What To Do When the Battery On Your PC’s Mother­board Goes Flat; Build A Guitar Headphone Amplifier; FM Radio Trainer, Pt.2; Transistor/Mosfet Tester For DMMs; A 16-Channel Decoder For Radio Remote Control; Introduction to Satellite TV. June 1995: Build A Satellite TV Receiver; Train Detector For Model Railways; 1W Audio Amplifier Trainer; Low-Cost Video Security System; Multi-Channel Radio Control Transmitter For Models, Pt.1; Build A $30 Digital Multimeter. July 1995: Electric Fence Controller; How To Run Two Trains On A Single Track (Incl. Lights & Sound); Setting Up A Satellite TV Ground Station; Build A Reliable Door Minder. August 1995: Fuel Injector Monitor For Cars; Gain Controlled Microphone Preamp; Audio Lab PC-Controlled Test Instrument, Pt.1; Mighty-Mite Powered Loudspeaker; How To Identify IDE Hard Disc Drive Parameters. September 1996: VGA Oscilloscope, Pt.3; IR Stereo Headphone Link, Pt.1; High Quality PA Loudspeaker; 3-Band HF Amateur Radio Receiver; Feedback On Pro­grammable Ignition (see March 1996); Cathode Ray Oscilloscopes, Pt.5. October 1996: Send Video Signals Over Twisted Pair Cable; Power Control With A Light Dimmer; 600W DC-DC Converter For Car Hifi Systems, Pt.1; IR Stereo Headphone Link, Pt.2; Build A Multi-Media Sound System, Pt.1; Multi-Channel Radio Control Transmitter, Pt.8. November 1996: Adding A Parallel Port To Your Computer; 8-Channel Stereo Mixer, Pt.1; Low-Cost Fluorescent Light Inverter; How To Repair Domestic Light Dimmers; Build A Multi-Media Sound System, Pt.2; 600W DC-DC Converter For Car Hifi Systems, Pt.2. December 1996: CD Recorders ­– The Next Add-On For Your PC; Active Filter Cleans Up CW Reception; Fast Clock For Railway Modellers; Laser Pistol & Electronic Target; Build A Sound Level Meter; 8-Channel Stereo Mixer, Pt.2; Index To Volume 9. January 1997: How To Network Your PC; Control Panel For Multiple Smoke Alarms, Pt.1; Build A Pink Noise Source (For Sound Level Meter Calibration); Computer Controlled Dual Power Supply, Pt.1; Digi-Temp Monitors Eight Temperatures. February 1997: Cathode Ray Oscilloscopes, Pt.6; PC-Controlled Moving Message Display; Computer Controlled Dual Power Supply, Pt.2; AlertA-Phone Loud Sounding Alarm; Control Panel For Multiple Smoke Alarms, Pt.2. March 1997: Driving A Computer By Remote Control; Plastic Power PA Amplifier (175W); Signalling & Lighting For Model Railways; Build A Jumbo LED Clock; Cathode Ray Oscilloscopes, Pt.7. April 1997: Avoiding Win95 Hassles With Motherboard Upgrades; Simple Timer With No ICs; Digital Voltmeter For Cars; Loudspeaker Protector For Stereo Amplifiers; Model Train Controller; A Look At Signal Tracing; Pt.1; Cathode Ray Oscilloscopes, Pt.8. May 1997: Teletext Decoder For PCs; Build An NTSC-PAL Converter; Neon Tube Modulator For Light Systems; Traffic Lights For A Model Intersection; The Spacewriter – It Writes Messages In Thin Air; A Look At Signal Tracing; Pt.2; Cathode Ray Oscilloscopes, Pt.9. June 1997: Tuning Up Your Hard Disc Drive; PC-Controlled Thermometer/ Thermostat; Colour TV Pattern Generator, Pt.1; Build An Audio/RF Signal Tracer; High-Current Speed Controller For 12V/24V Motors; Manual Control Circuit For A Stepper Motor; Fail-Safe Module For The Throttle Servo; Cathode Ray Oscilloscopes, Pt.10. July 1997: Infrared Remote Volume Control; A Flexible Interface Card For PCs; Points Controller For Model Railways; Simple Square/Triangle Wave­ form Generator; Colour TV Pattern Generator, Pt.2; An In-Line Mixer For Radio Control Receivers; How Holden’s Electronic Control Unit works, Pt.1. September 1995: Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.1; Keypad Combination Lock; The Vader Voice; Jacob’s Ladder Display; Audio Lab PC-Controlled Test Instrument, Pt.2. August 1997: The Bass Barrel Subwoofer; 500 Watt Audio Power Amplifier Module; A TENs Unit For Pain Relief; Addressable PC Card For Stepper Motor Control; Remote Controlled Gates For Your Home; How Holden’s Electronic Control Unit Works, Pt.2. October 1995: Geiger Counter; 3-Way Bass Reflex Loudspeaker System; Railpower Mk.2 Walkaround Throttle For Model Railways, Pt.2; Fast Charger For Nicad Batteries; Digital Speedometer & Fuel Gauge For Cars, Pt.1. September 1997: Multi-Spark Capacitor Discharge Ignition; 500W Audio Power Amplifier, Pt.2; A Video Security System For Your Home; PC Card For Controlling Two Stepper Motors; HiFi On A Budget; Win95, MSDOS. SYS & The Registry. November 1995: Mixture Display For Fuel Injected Cars; CB Trans­ verter For The 80M Amateur Band, Pt.1; PIR Movement Detector; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.1; Digital Speedometer & Fuel Gauge For Cars, Pt.2. October 1997: Build A 5-Digit Tachometer; Add Central Locking To Your Car; PC-Controlled 6-Channel Voltmeter; 500W Audio Power Amplifier, Pt.3; Customising The Windows 95 Start Menu. December 1995: Engine Immobiliser; 5-Band Equaliser; CB Trans­ verter For The 80M Amateur Band, Pt.2; Subwoofer Controller; Dolby Pro Logic Surround Sound Decoder Mk.2, Pt.2; Knock Sensing In Cars; Index To Volume 8. November 1997: Heavy Duty 10A 240VAC Motor Speed Controller; Easy-To-Use Cable & Wiring Tester; Build A Musical Doorbell; Relocating Your CD-ROM Drive; Replacing Foam Speaker Surrounds; Understanding Electric Lighting Pt.1. January 1996: Surround Sound Mixer & Decoder, Pt.1; Magnetic Card Reader; Build An Automatic Sprinkler Controller; IR Remote Control For The Railpower Mk.2; Recharging Nicad Batteries For Long Life. December 1997: A Heart Transplant For An Aging Computer; Build A Speed Alarm For Your Car; Two-Axis Robot With Gripper; Loudness Control For Car Hifi Systems; Stepper Motor Driver With Onboard Buffer; Power Supply For Stepper Motor Cards; Understanding Electric Lighting Pt.2; Index To Volume 10. February 1996: Three Remote Controls To Build; Woofer Stopper Mk.2; 10-Minute Kill Switch For Smoke Detectors; Basic Logic Trainer; Surround Sound Mixer & Decoder, Pt.2; Use your PC As A Reaction Timer. January 1998: Build Your Own 4-Channel Lightshow, Pt.1 (runs off 12VDC or 12VAC); Command Control System For Model Railways, Pt.1; Pan Controller For CCD Cameras; Build A One Or Two-Lamp Flasher; Understanding Electric Lighting, Pt.3. February 1998: Hot Web Sites For Surplus Bits; Multi-Purpose Fast Battery Charger, Pt.1; Telephone Exchange Simulator For Testing; Command Control System For Model Railways, Pt.2; Demonstration Board For Liquid Crystal Displays; Build Your Own 4-Channel Light­ show, Pt.2; Understanding Electric Lighting, Pt.4. April 1998: Automatic Garage Door Opener, Pt.1; 40V 8A Adjustable Power Supply, Pt.1; PC-Controlled 0-30kHz Sinewave Generator; Build A Laser Light Show; Understanding Electric Lighting; Pt.6; Jet Engines In Model Aircraft. May 1998: Troubleshooting Your PC, Pt.1; Build A 3-LED Logic Probe; Automatic Garage Door Opener, Pt.2; Command Control For Model Railways, Pt.4; 40V 8A Adjustable Power Supply, Pt.2. June 1998: Troubleshooting Your PC, Pt.2; Understanding Electric Lighting, Pt.7; Universal High Energy Ignition System; The Roadies’ Friend Cable Tester; Universal Stepper Motor Controller; Command Control For Model Railways, Pt.5. July 1998: Troubleshooting Your PC, Pt.3 (Installing A Modem And Sorting Out Any Problems); Build A Heat Controller; 15-Watt Class-A Audio Amplifier Module; Simple Charger For 6V & 12V SLA Batteries; Automatic Semiconductor Analyser; Understanding Electric Lighting, Pt.8. August 1998: Troubleshooting Your PC, Pt.4 (Adding Extra Memory To Your PC); Build The Opus One Loudspeaker System; Simple I/O Card With Automatic Data Logging; Build A Beat Triggered Strobe; A 15-Watt Per Channel Class-A Stereo Amplifier. September 1998: Troubleshooting Your PC, Pt.5 (Software Problems & DOS Games); A Blocked Air-Filter Alarm; A Waa-Waa Pedal For Your Guitar; Build A Plasma Display Or Jacob’s Ladder; Gear Change Indicator For Cars; Capacity Indicator For Rechargeable Batteries. October 1998: CPU Upgrades & Overclocking; Lab Quality AC Milli­ voltmeter, Pt.1; PC-Controlled Stress-O-Meter; Versatile Electronic Guitar Limiter; 12V Trickle Charger For Float Conditions; Adding An External Battery Pack To Your Flashgun. November 1998: Silicon Chip On The World Wide Web; The Christmas Star (Microprocessor-Controlled Christmas Decoration); A Turbo Timer For Cars; Build Your Own Poker Machine, Pt.1; FM Transmitter For Musicians; Lab Quality AC Millivoltmeter, Pt.2; Beyond The Basic Network (Setting Up A LAN Using TCP/IP); Understanding Electric Lighting, Pt.9; Improving AM Radio Reception, Pt.1. December 1998: Protect Your Car With The Engine Immobiliser Mk.2; Thermocouple Adaptor For DMMs; A Regulated 12V DC Plugpack; Build Your Own Poker Machine, Pt.2; GM’s Advanced Technology Vehicles; Improving AM Radio Reception, Pt.2; Mixer Module For F3B Glider Operations. January 1999: The Y2K Bug & A Few Other Worries; High-Voltage Megohm Tester; Getting Going With BASIC Stamp; LED Bargraph Ammeter For Cars; Keypad Engine Immobiliser; Improving AM Radio Reception, Pt.3; Electric Lighting, Pt.10 February 1999: Installing A Computer Network (Network Types, Hubs, Switches & Routers); Making Front Panels For Your Projects; Low Distortion Audio Signal Generator, Pt.1; Command Control Decoder For Model Railways; Build A Digital Capacitance Meter; Remote Control Tester; Electric Lighting, Pt.11. March 1999: Getting Started With Linux; Pt.1; Build A Digital Anemometer; 3-Channel Current Monitor With Data Logging; Simple DIY PIC Programmer; Easy-To-Build Audio Compressor; Low Distor­ tion Audio Signal Generator, Pt.2; Electric Lighting, Pt.12. April 1999: Getting Started With Linux; Pt.2; High-Power Electric Fence Controller; Bass Cube Subwoofer; Programmable Thermostat/ Thermometer; Build An Infrared Sentry; Rev Limiter For Cars; Electric Lighting, Pt.13; Autopilots For Radio-Controlled Model Aircraft. May 1999: The Line Dancer Robot; An X-Y Table With Stepper Motor Control, Pt.1; Three Electric Fence Testers; Heart Of LEDs; Build A Carbon Monoxide Alarm; Getting Started With Linux; Pt.3. June 1999: FM Radio Tuner Card For PCs; X-Y Table With Stepper Motor Control, Pt.2; Programmable Ignition Timing Module For Cars, Pt.1; Hard Disk Drive Upgrades Without Reinstalling Software; What Is A Groundplane Antenna?; Getting Started With Linux; Pt.4. July 1999: Build The Dog Silencer; A 10µH to 19.99mH Inductance Meter; Build An Audio-Video Transmitter; Programmable Ignition Timing Module For Cars, Pt.2; XYZ Table With Stepper Motor Control, Pt.3; The Heapod Robot. August 1999: Remote Modem Controller; Daytime Running Lights For Cars; Build A PC Monitor Checker; Switching Temperature Con­ troller; XYZ Table With Stepper Motor Control, Pt.4; Electric Lighting, Pt.14; DOS & Windows Utilities For Reversing Protel PC Board Files. September 1999: Automatic Addressing On TCP/IP Networks; Wireless Networking Without The Hassles; Autonomouse The Robot; Voice Direct Speech Recognition Module; Digital Electrolytic Capacitance Meter; XYZ Table With Stepper Motor Control, Pt.5; Peltier-Powered Can Cooler. PLEASE NOTE: November 1987 to August 1988, October 1988 to March 1989, June 1989, August 1989, December 1989, May 1990, August 1991, February 1992, July 1992, September 1992, November 1992, December 1992 and March 1998 are now sold out. All other issues are presently in stock. For readers wanting articles from sold-out issues, we can supply photostat copies (or tear sheets) at $7.00 per article (includes p&p). When supplying photostat articles or back copies, we automatically supply any relevant notes & errata at no extra charge. A complete index to all articles published to date is available on floppy disc for $10 including p&p, or can be downloaded free from our web site: www.siliconchip.com.au October 1999  89 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Write to: Ask Silicon Chip, PO Box 139, Collaroy Beach, NSW 2097. Basic software for Spacewriter I am writing to you as I have bought a couple of Space­writer kits as described in the May 1997 issue. An employee of mine also bought one and wrote to you requesting the software for them and as suggested I downloaded the program from your site. However, both he and I have failed to get the software to operate on QBasic or any other software we operate. My operating system is NT3.51 so I can not open it using Explorer or directly from the file manager as it must be associated to something. With QBasic it opens but is a lot of gobble-de-gook and certainly not the screens as shown in the SILICON CHIP May 1997 article. For my use I really require a longer string of letters and the use of an EPROM so that the memory is not lost with a power shut down as I wish to use them as a spinning disc display con­nected to the mains supply. Do you know of any other circuits to provide these criteria? As a builder of interactive exhibits this so beautifully demonstrates eye retention. (I. P., via email). •  The software for the Space­writer is designed to operate from DOS rather Compressor for car CD player I am not convinced that the CD player is the ideal medium for providing music while you drive as the wide dynamic range of the CD makes it difficult to hear the quiet passages above the background of road/tyre noise whilst the loud passages can be uncomfortably high inside a car with the windows shut. Therefore, I would like to request you describe a circuit of an audio com­pressor suitable to handle the higher voltage input that a CD player generates. This could also 90  Silicon Chip than Windows 95/98 or NT. The .exe file is a free standing file which does not require QBasic to run it. It cer­ tainly will show many unrecognisable characters if this file is loaded into QBasic. However the accompanying spcwri.bas file can be run in QBasic. We have not published any other projects which demonstrate the persistence of vision in this manner. Waa-Waa effect with bass guitar I was over the moon when you published the Waa-Waa Pedal in the September 1998 issue. I rushed out and bought it straight away. After spending a week or two on the kit I went and plugged it into my amplifier. I first plugged in my acoustic guitar fitted with a piezoelectric pickup. After setting the volume correctly it worked like a charm. Then I plugged in my electric bass but there was no effect. The sound coming through was almost muted, no matter what position the pedal was in. Initially, I thought I needed to readjust it but rotating the pots made no difference. Could the Waa-Waa unit be filtering out my bass? If so, how can I fix it? (R. R., via email). •  The Waa-Waa Pedal as originally be used to produce tapes from CDs for use in a tape player. You have described an audio com­pressor in the March 1999 issue of SILICON CHIP but this is only suitable for microphone inputs. (B. P., Port Macquarie, NSW). •  We published a CD Compressor in the March 1989 issue and although it used balanced supply rails it would be possible to modify the design to work with a single 12V rail since the com­pressor chip itself ran from a single supply. We can supply a photostat copy of this article for $7.00 including postage. presented was designed to operate over the nominal range of 50Hz to 2.8kHz but most of this range is beyond the output of your bass guitar. It could be modified to have more effect on your bass guitar by altering the capacitor components on IC2 and IC3. Try using a .0018µF capaci­tor between pins 6 & 7 of IC3. The filter on IC2 will require changing so that the .039µF capacitor is 0.15µF and the .0047µF capacitor is .018µF. Also ideally, the 0.22µF capacitor at the input of the circuit should be doubled in value to say 0.47µF. However, while this will make the unit more effective for bass guitars, the effect on lead guitars might not be as good as before. Transistors for power amplifiers I have a number of MJ15024/25s (8 pairs) and wish to use these as audio amplifiers. A few pointers from yourselves would be helpful. Which bipolar designs have been published by SILICON CHIP?. (Is it the Hitachi topology?) What modifications can be made in light of the apparent increase in SOAR parameters over the MJ15003/4 devices? Can a benefit be arrived at by using a separate power supply to the voltage/power stages; ie, a regulated voltage stage/rectified filtered power stage? I do recall reading some­where that variations at the collector of a power amplifier contribute little to distortion overall. (B. W., via email). •  We have published three designs which are relevant; in February 1988, April 1996 and March 1997. The first used the Hitachi topology and was based on MJ15003/4s. The other two were plastic MJL21193/94 designs but could use the MJ15024/25. We would not be inclined to boost supply rails unless you compute the inductive load/line curves and use bigger heat­sinks. A separate power supply for the voltage amplifier stages can be bene- ficial but only if the wiring layout is arranged for the best THD result. The improvement is small though. 12V strobe light wanted I am looking for a xenon flash tube strobe circuit that will work from 12V. Has SILICON CHIP done anything like this? I want to strobe it in a certain pattern and can achieve that with a 4017 counting circuit but I am stuck for the voltage multipli­er/trigger for the tube. Can you help? (M. W., via email). •  We have not published a 12V strobe light circuit as such but you could easily adapt one from some of the circuits we have already published. You will need an inverter which produces about 340V DC and we would suggest the circuit for the electric fence in the April 1999 issue. You could then adapt some of the circuit of the Beat Triggered Strobe featured in the August 1998 issue. Acoustic delay to feedback howl I am interested in your 20ms delay kit published in the March 1996 issue. If I added it to both channels of the PA at my church (output-speakers), would this get rid of any possible feedback? (E. A., via email). •  We doubt whether a 20ms delay would stop acoustic feedback. The recognised howl suppression technique is to use a frequency shifter. We don’t know whether such units are available commer­cially in Australia but we did an article on the technique in the June 1991 issue. Overheating school project I have made your 100W amplifier kit and it’s been used in an active subwoofer I also made. So far it’s working great but as this is my major project for school this year I have found that it is overheating and wasting energy. I need to find a circuit that would auto power it off after it receives no signal for a number of minutes (20 would be nice but it doesn’t matter). If you could help me it would be greatly appreciated. All I need is the bare circuit. (G. R., via email). •  We are concerned that your am- Feeding a guitar into a sound card Is it possible to use a speaker output as a standard guitar input on my Gina hard disk recording card. I have been doing a bit of recording (I am a muso) into my computer through a Gina hard disk recording card which works extremely well. Usually I plug a guitar or microphone through a separate preamp into the jack socket inputs of the Gina Card. I would now like to record an instrumental using an old Fi-Sonic 60W valve guitar amplifier and would like to duplicate the sound as closely as possible. I have tried various microphones in front of the speaker but I need to turn up the gain of the recording card very high to obtain a reasonable input to the computer. Al- plifier is overheating. This should be fixed regardless of whether you use a power-off circuit or not. Have you set the quiescent current properly? If the quiescent current is not stable, perhaps the amplifier could be super­ sonically unstable. A subwoofer controller and power off circuit was published in the December 1995 issue. Heavy duty servo wanted I’ve always wondered if it is possible to connect or make a servo which will drive a heavier steering system than that of a remote control car. The unit would still have to interface to the existing radio equipment and be compatible to use the existing impulses. Any help would be greatly appreciated. (K. C., via email). •  We featured a circuit for a servo using a windscreen wiper motor in the December 1997 issue. Low foldback current limit on power supply A couple of years ago I built the adjustable 45V 8A supply published in the January & February 1992 issues of SILICON CHIP. While the power supply functions very well, it has always though this works it generates too much noise. Alternatively, I turn up the speaker so loud as to drive my neighbours nuts. I could probably find the output from the valve preamplifier but would really like to try the speaker output straight into the hard disk recording card to obtain the output sound as close as possible to the speaker output. I would appreciate your advice. (V. S., via email). •  We suggest you connect the speaker output of your guitar amplifier to your sound card via a voltage divider across the output of your amplifier. This could take the form of a 22kΩ resistor in series with (say) a 2.2kΩ resistor to ground. The tap off point is from the junction of the two resistors. If the signal is still too high, reduce the 2.2kΩ resistor. had a problem in that it will not start up with a load connected. If I have a resistive load which draws more than about 0.5A connected to the output terminals with the ‘Load’ switch on and I then switch on the mains power, the unit emits a very audible ‘squawk­ ing’ sound and will not come up to the set voltage until I dis­connect the load. Once I do this, the squawking stops, the output voltage comes up and I can reconnect the load. But once I have the power supply up and running with some arbitrary resistive load connected, I can wind up the output voltage with a corresponding increase in output current until I get to about 7.5A. At this point the output voltage drops, the unit starts squawking again and I again have to disconnect the load to get things going. Note that the current overload adjust­ ment is set to maximum. Has this problem been documented pre­viously and do you have any tips on overcoming it? (Noel; via email). •  This power supply includes a foldback current feature which reduces the current to a low level if a critical current level is reached. This operates independently to the normal current limit and can override its operation. The load must be removed before the foldback limiting can be released. October 1999  91 me when it was? (M. M., via email). Smoke alarm panel has chirping problem I have a couple of questions about the Control Panel for Smoke Alarms featured in the January 1997 issue of SILICON CHIP. I have hooked up a smoke alarm and the following fault occurs: the smoke alarm ‘barks’ with a pulse on the piezo once every 55 seconds. I have checked all my wiring and soldering prior and during assembly and after completion. I cannot get it to pull the ionisation chamber low for a Test on any of the test points. It disarms and rearms both the 1st & 2nd smoke alarms. No problems. The red LED does not illu­ minate to indicate that it is off-line. Can you supply me with some test points for waveforms to observe and can you offer any further advice? (C. L., via email). •  The chirp from your smoke alarm is possibly due to the 9V supply rail being sufficiently low to set off the “low battery” alarm within the smoke alarm. Check the supply for 9V and if necessary The description of this circuit is on page 72 of the January 1992 issue. Your power supply operates as intended but it does appear to have a lower overcurrent limit than the expected 9A. Check the 12V supply to verify that this is between 11.5 and 12.5V and the voltage at pin 11 of IC3 is at 0.45V. This voltage sets the overcurrent limit. If necessary, you can increase this voltage (and hence the overcurrent limit) by increasing the total value of the 1.1kΩ and 820Ω resistors connecting pin 11 of IC3c to the “B” 0V supply rail. The fact that the power supply does not start up with a load connected is also due to the over-current limiting action. This occurs because a 10µF capacitor across the limit setting resistors holds the voltage at pin 11 of IC3c low at the instant the power supply is switched on. The effective over-cur­rent limit is therefore at a very low value. If there is a load connected it will be detected as an over-current and the foldback limit will occur. 92  Silicon Chip you can increase the voltage by increasing the value of the 100Ω resistor between the ADJ terminal of REG1 and the 680Ω resistor. Each 100Ω added to this resistance will increase the output by about 1V. The Disarm LEDs may not light because they are possibly inserted with the incorrect polarity. Check that the pin 1 output of IC8a goes low when Alarm 1 is disarmed. Similarly, pin 13 of IC8b should be low when Alarm 2 is disarmed. The test function will not work if the smoke alarm itself will not sound the alarm when its test switch is pressed. If this works, check that the collector of transistor Q4 goes low (to ground) when the alarm test is activated. If not, check diode D43 and the resistor values on either side of the diode. Note that the test feature is only activated for the alarm when that par­ticular alarm is polled by the smoke alarm monitor. This means that the monitor LED for the particular smoke alarm must be lit before the alarm test will sound the alarm in the unit under test. If you wish to delete this over-current feature you can do so by changing the connection of the 10µF connected between the junction of the 22kΩ and 27kΩ resistors (part of the over-current setting network) and the “B” 0V supply. The positive side of the 10µF capacitor should connect to the +12V rail while the negative terminal of the capacitor should connect to the junction of these resistors (ie, 22kΩ & 27kΩ). On the overlay diagram, this 10µF capacitor is located directly below the 0.1µF capacitor which is directly below pin 16 of IC3. Remove the capacitor and place the (-) lead where the + side should be and connect the + lead to the 12V supply. The 12V can be obtained from the output of the 7812 regulator or from a component which has 12V on it. Article on NE572 compandor chip I’m looking for the article on NE571 or NE572 compandors. Can you tell •  The NE572 compressor chip was featured twice in the March 1989 issue; a data article and a construction article. We can supply the two photostat articles for a total of $7 including postage. High energy ignition for a Morris Minor I have just built the Universal High Energy Ignition kit (described in the June 1998 issue) to fit to a Datsun 120Y engine in a 1953 Morris Minor) but I have found the text a little lighton when it gets to actually wiring the unit to your engine. (1) When connecting the wire to the points and the wire to the negative side of the coil, do I remove the wires already there? (2) Is it OK to run the coil output wire through the same hole as the trigger input wire? The kit I bought from Jaycar has only one rubber grommet and says to run all external wiring through the one hole in the kits casing. Your article specifically mentions keeping the coil output separate from the trigger input wire. (3) If the car won’t show any sign of starting, is there a step-by-step test procedure? I normally would get right in there with the meter, but the voltages sound a little scary. (P. R., via email). •  You do disconnect existing wiring from the points to the coil. You can run the coil output wire through the same hole as the trigger wire providing that the coil wire has 500V-rated insulation. If the unit does not show signs of starting the engine, it would be wise to check your wiring and the construc­tion of the circuit board. Check the isolation of the transistor from the case. SLA charger not delivering enough Some time ago I assembled a 6V SLA battery charger kit bought from Altronics. The battery to be charged is a Panasonic 6V 4A.h SLA type. On the battery, the charging voltage is quoted at 7.25V and the standby voltage at 6.8V. When I checked the voltages of the charger with a digital meter, during charging the voltage was 6.8V with a current of 500mA. When the battery was fully charged at 0mA current, the standby voltage was also 6.8V. Then I borrowed another 6V SLA battery charger from a friend and both the charging and standby voltage of this charger were 7.25V. I wonder which charger is working correctly or neither. I would appreciate it if you would enlighten me as to how to make the vol­tages of my charger within specifications. (A. H., via email). •  We have obtained the kit information on the 6V version of the SLA charger from Altronics and we can confirm that all the component values are exactly as they should be, according to the data on the UC3906 chip. Its over-charge voltage is 7.4V and its float voltage is 6.9V. We published a detailed article on the UC3906 in the March 1990 issue. Provided all the resistor values are as specified on your circuit, the charger should work cor­rectly. Notes & Errata Voice Direct Speech Recognition, September 1999: both the circuit on page 38 and the PC board overlay diagram incorrectly show the 4081 AND gate packages connected to the +12V rail rather than the +5V rail as they should be. If you have built the board as published, the +12V rail from the relay to pin 14 of both 4081s should be broken and the line connected to +5V instead. An amended PC pattern has been produced and can be down­loaded from our website. Autonomouse Robot, September 1999: there are number of errors on the circuit on pages 20 & 21. The 1N914 below D3 should be Mailbag: continued from page 44 of temperature rise. When mounted on a PC board, the copper track of the source lead is used to dissipate this heat as is the drain track. When trying to mount TO-220 packages on any standard off-theshelf heatsink, where multiple transistors are required to be placed in parallel, then the wiring of these devices becomes quite painful, tedious and delicate and looks disastrous. Problems that can occur during testing include the difficulty in probing with a CRO safely due to the close proximity of the drain and gate leads. One slip of the CRO probe and you can kiss the FETs good­bye. If paralleled (28 per side on the inverter that I am pre­sently repairing), then they all fail. Also it is quite a common occurrence to have the FETs burn the PC board to a crisp which renders it extremely difficult to repair, with a 1500W inverter costing $1000 to replace the one and only PC board. What I am leading to is that in applications where high powers are required then maybe the TO-220 package is not the most desirable but it is used quite commonly as its cost is most attractive. What I am advocating here is that a transistor manu­facturer should consider making a true 50A transistor. A typical example would be perhaps three or four 60NO6 FETs mounted in a reverse TO-3 package with spade terminals, such that the drain and source leads can actually carry the 50A and be mechanically and thermally stable at the same time. Another alternative is the package used for bridge rectifi­ers. Here we have a package, usually alumini- D4, not Q4. The collector leads of Q5 & Q13 are labelled “B” instead of “C”. Finally, the text on page 23 refers to a 100kΩ resistor associated with IC3. The value is 390kΩ, as indicated on the circuit and wiring diagrams. Surveillance Lights With Buzzer, Circuit Notebook, September 1999: NAND gate IC1a is shown reversed. Input pins 1 & 2 should connect to the PIR output. Switching Temperature Controller, August 1999: the reference on page 55 to the Seeburg effect is wrong; it should be the Seebeck effect. Seeburg is a brand of jukebox! um-based, with four spade connectors and four diodes encapsulated. It is cheap, and it will fit down the centre of most grunty heatsinks and has a good base for heat transfer. It also uses a single-bolt mount and is easily insulated if required. The lead configuration would be 10mm spade lug for drain on one side and source on the opposite side with the 3mm spade lug for the gate on the third side. This configuration would clarify that it was not a bridge rectifier. This basic configuration would lend itself extremely well to the manufacturing of bridge transistor circuits or parallel configuration as it would leave the running of copper busses wide open, with unlimited flexibility in connection methods; eg, spade lugs or copper braid or copper wire or strip busses. T. C. Thrum, Para Hills West, SA. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. October 1999  93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FRWEEBE YES! Place your classified advertisement in SILICON CHIP Market Centre and your advert will also appear FREE in the Classifieds-on-the-Web page of the SILICON CHIP website, www.siliconchip.com.au And if you include an email address or your website URL in you classified advert, the links will be LIVE in your classified-on-the-web! S! D E I F I S C LAS EXCLUSIVE TO SILICON CHIP! CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $11.00 (incl. GST) for up to 12 words plus 55 cents for each additional word. Display ads: $27.50 (incl. GST) per column centimetre (max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly in the space below or on a separate sheet of paper, fill out the form & send it with your cheque or credit card details to: Silicon Chip Classifieds, PO Box 139, Collaroy, NSW 2097. Or fax the details to (02) 9979 6503. Taxation Invoice ABN 49 003 205 490 _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ _____________ Enclosed is my cheque/money order for $­__________ or please debit my ❏ Bankcard   ❏ Visa Card   ❏ Master Card Card No. Signature­­­­­­­­­­­­ ________________________  Card expiry date______/______ Name _____________________________________________________ Street _____________________________________________________ Suburb/town _________________________  Postcode______________ 94  Silicon Chip FOR SALE TELEPHONE EXCHANGE SIMULATOR, SC Feb. 1998. Test equipment without the cost of telephone lines. $190. MAGNETIC CARD READER, SC Jan. 1996. Holds up to 8 cards. Use as a door lock. $65. Melbourne 9806 0110. ELECTRONIC/MECHANICAL DESIGN AND CONSTRUCTION: we offer a complete design service for electronic and mechanical devices. Most work is done in house and you deal directly with the designers. No job is too small and can be to prototype or “turn key” stage, in one offs or for future production. Simply send us an email at vladimir<at>u030.aone.net.au with your questions or requirements and we will get back to you. WEATHER STATIONS: Windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. $420.00 complete plus sales tax if appli­cable. Optional rainfall and PC interface. Used by Government Departments, farmers, pilots, and weather enthusiasts. Other models with barometric pressure, humidity, dew point, solar radiation, UV, leaf wetness, etc. Just phone, fax or write for our FREE catalogue and price list. Solar Flair/ Ecowatch ph: (03) 5968 4863 fax: (03) 5968 5810, PO Box 18, Emerald, Vic., 3782. ACN 006 399 480. PRINTED CIRCUIT BOARDS for all magazine projects, then go to http:// www.cia.com.au/rcsradio RCS Radio – Bexley (+61 2) 9587 3491. STAMP 2: complete development system consisting of Basic Stamp 2, Stamp 2 carrier board, stamp jumper connectors, Basic Stamp 2 development kit (consisting of a comprehensive manual, development software and cables). Never been used. The lot for half retail price $160. Phone Spencer on (02) 4871 1953 or email brown_spencer_9<at>hotmail.com ELECTRONICS FOR BEGINNERS COURSES, including DC & AC Principles and Operational Amplifiers. Enquiries: 02 9130 7988. WORKBOOKS FOR SALE: “Electronics For Beginners”: Stage 1, DC Electrical Principles; Stage 2, AC Electrical Principles & Operational Amplifiers. Phone 02 9130 7988. Win $500USD cash dontronics.com PC-CONTROLS: Receiver 144148MHz (PLL), DS2401 ID-Reader, Temperature Recorder (DS1615), AF Generators, Temperature measurement, I/O cards, Data Logging, ActiveX. Ph/Fax (02) 9482 1565. http:// www.ar.com.au/~softmark Need prototype PC boards? We have the solutions – we print electronics! Four-day turnaround, less if urgent; Artwork from your own positive or file; Through hole plating; Prompt postal service; 29 years technical experience; Inexpensive; Superb quality. Printed Electronics, 12A Aristoc Rd, Glen Waverley, Vic 3150. Phone: (03) 9545 3722; Fax: (03) 9545 3561 Call Mike Lynch and check us out! We are the best for low cost, small runs. Satellite TV Reception International satellite TV reception in your home is now affordable. Send for your free info pack containing equipment catalog, satellite lists, etc or call for appointment to view. We can display all satellites from 76.5° to 180°. Positions At Jaycar We are often looking for enthusiastic staff for positions in our retail stores and head office at Rhodes in Sydney. A genuine interest in electronics is a necessity. Phone 02 9743 5222 for current vacancies. KITS-R-US PO Box 314 Blackwood S.A. Ph/fax 08 8270 3175 FMTX2A Universal Stereo Coder $49 FMTX2B 30mW Xtal Locked 100MHz Transmitter $49 FMTX1 1-3 Watt Free Running Transmitter $49 FMX1 200mW Full Broadcast Transmitter, built & tested $499 FM220 10-18 Watt FM BGY133 Philips Linear $499 FM1525 25 Watt Discrete Linear FM Band $499 FM2100 110 Watt Discrete Linear FM Band $699 FM3000 300 Watt Discrete Linear FM Band $1499 Philips 828E/A VHF Receiver Boards (6 metres) $9 AWA 721 VHF Receiver Boards (2 metres) $9 AWA 721 VHF transmitter boards 1 watt (2 metres) $19 Philips 323 UHF transmitter boards 500mW (70cm) $19 AEM 35 Watt Little Brick Audio Power Amp $15 Digi-125 200W RMS Audio Power Amp $39 CA Clipper Compiler, new in box $49 6dBd Gain Colinear FM Band Antenna $999 Roll Smart-1 FM Station Audio Processor $999 Free catalog on disk of discounted surplus components Same day shipping, credit cards OK, circuits supplied. SPECIAL STEAM BOAT KITS $14 FREE Heat Shrink Tubing with Camera orders this Month * VIDEO & STEREO 2.4 GHz Multi Channel TRANSMITTERS & Scanning RECEIVERS from $142 * PIR MOVEMENT DETECTOR inbuilt concealed PINHOLE Mono or DSP COLOUR Camera, Microphone & Timer/Controller for VCR - Lights - etc from $139 * BULLET CAMERAS 22 mm dia 480 Line 0.05 lux SONY CCD or DSP COLOUR from $132 * QUADS 4 Pix 1 screen from $256 HI-RES better than SUPER-VHS Quality * Modules 32 x 32 from $76 also with Tiny Hi-Sens On-Board MICROPHONE * COLOUR DSP 32 x 32 mm Pinhole Module with MICROPHONE from $155 * MINI 36 x 36 from $85 - SONY CCD $102 - COLOUR DSP $162 * DOME from $88 - SONY CCD $105 COLOUR DSP $164 * Video BALUNS from $11 * DIY PAKS: 4 Cameras, Switcher & Supply from $499 - with 14" Monitor from $601 with MUX for FULL SCREEN / RESOLUTION RECORDING from $1209 * 4 COLOUR CAMERAS, SWITCHER & POWER SUPPLY from $807 - with COLOUR QUAD 4 Pix 1 Screen from $1211 * With MUX $2033 * COLOUR QUADS from $512 * COLOUR DUPLEX MUX from $1329 * 14" MONITORS from $218 - with Inbuilt 4 Ch SWITCHER from $256 * SEE-in-the-DARK CAMERA & INFRARED ILLUMINATOR Kits from $19 * ANCILLARY EQUIPMENT * DISCOUNTS * BEFORE YOU BUY Ask about New Enquiry Offer & visit our Web Site at www.allthings.com.au Ph (08) 9349 9413 Fax 08 9344 5905 AV-COMM P/L, 198 Condamine St, Balgowlah, NSW 2093. Tel: 02 9949 7417 or 9948 2667. Fax: 9949 7095; www.avcomm.com.au Silvertone’s RC Receiver Still the best little performer available! Ph: (03) 98306288     Fax: (03) 98306481 1/3 PRICE HEATSHRINK TUBING. CSA UL 125C 2 : 1 Shrink GP 600 Volt from 20 cents. www.allthings.com.au SATELLITE TV DIGITAL RX NTSC to PAL MPEG-2 FTA EPG Encryp­tion CAM from $399. www.allthings.com.au C COMPILERS: everything you need to develop C and ASM software for 68HC08, 6809, 68HC11, 68HC12, 68HC16, 8051/52, 8080/85, 8086, 8096 or AVR: $155.00 each. Macro Cross Assemblers and Disassemblers for above CPUs + 6800/01/03/05, 6502 and 68HC12 for $78. Debug monitors: $78 for 6 CPUs. All compilers, XASMs and monitors: $480. 8051/52 Simulator (fast, now incl. 80C320): $78. Try the C-FLEA Virtual Machine for small CPUs, build a “C-Stamp”. Demo desk: FREE. All prices + $5 p&p. Atmel Flash CPU Programmer: Handles the 89Cx051, the 89C5x Still only $129.50 AM or $149.50 FM. May be used with most ppm transmitters. This and many other radio control products available from: Silvertone Electronics, PO Box 580, Riverwood 2210. Phone/Fax (02) 9533 3517. www.silvertone.com.au and 89Sxx series, and the new AVRs in both DIP and PLCC44. Also does most 8-pin EEPROMs. Includes socket for serial ISP cable. $199, $37 tax, $10 p&p. SOIC adaptors: 20-pin $90, 14-pin $85, 8-pin $80. Credit cards accepted. GRAN­TRONICS PTY LTD, PO Box 275, Wentworthville 2145. Ph (02) 9896 7150; Fax (02) 9631 1236; or Internet: http://www.grantronics.com.au October 1999  95 Silicon Chip Binders Keep your copies safe, secure and always available with SILICON CHIP binders: they’re cheap insurance! REAL VALUE AT $12.95 PLUS P &P   Heavy board covers with 2-tone green vinyl covering Advertising Index Altronics................................. 34-36 Aust. Audio Consultants...............73 Av-Comm Pty Ltd.........................95 Clarke & Severne........................73 Coffs Harbour Electronics............73   Each binder holds up to 14 issues so that you can include catalogs Computronics Corporation..........73 Convoy International................OBC  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Dick Smith Electronics........... 12-15 EMC Technologies.......................73 Harbuch Electronics....................71 Price: $12.95 plus $5 p&p each (available Aust. only) Instant PCBs................................95 Order by phoning (02) 9979 5644 & quoting your credit card number; or fax the details to (02) 9979 6503; or mail your order with cheque or credit card details to Silicon Chip Publications, PO Box 139, Collaroy, NSW 2097. Janteknology Distribution..........IFC Jaycar .............................. 45-52,95 Kalex............................................69 Kits-R-Us.....................................95 SATELLITE TV on your PC * PCI Card * Digital MPEG Video & Audio * High Speed Internet down link * Record Full Motion Video off-Air * www.allthings.com.au SOLAR PANELS: 120 watt $995.00, 80 watt $650.00, 60 watt $510.00, 40 watt $395.00 (all with 25 year guarantee). UNBREAKABLE PANELS: 64 watt $550.00, 42 watt $420.00, 32 watt $340.00, 11 watt $190.00, 5 watt $120.00, 1.25 watt $80.00. WIND GENERATORS: 400 watt $950.00. INVERTERS: sinewave inverters, inverter/chargers, mod. Sinewave inverters, call with requirements. AUST­RALIA WIDE DELIVERY (Free on orders over $500.00). TASMAN ENERGY: (03) 6362 3050 Fax (03) 6362 3054. VIDEO STEREO TRANSMITTERS & RECEIVERS $149 Multi Channel up to 500 metres. www.allthings.com.au RAIN BRAIN AND DIGI-TEMP KITS: 8 station sprinkler controllers, 60 channel temp monitor uses DS1820s over 500 metres. Has PC Data logging. Mantis Micro Products, http://www.home.aone.net.au/mantismp MicroZed Computers...................73 Oatley Electronics........................19 Printed Electronics...................... 95 Procon Technology......................95 PCBS MADE, ONE OR MANY. Low prices, hobbyists welcome. Sesame Electronics (02) 9554 9760 sesame<at>internetezy.com.au; http:// members.tripod.com/~sesame_elec Questronix...................................73 BITZ 25W Transceivers Sat TV RXs VCRs ABS CROs Yagis Isolation TXs CCTV Equip Gas Detectors 16 mm Projectors Components www.allthings.com.au Silicon Chip Back Issues....... 88-89 KIT ASSEMBLY Solar Flair/Ecowatch....................94 ANY KITS assembled/repaired: professional, speedy service. Phone Nev­ille Walker (07) 3857 2752. HELP SAVE THE NIGHT SKY! We are losing our heritage of starry night skies. Poor, inefficient outdoor lighting is causing glare and “light pollution”. This wastes energy and increases greenhouse gas emissions. You can help by joining SYDNEY OUTDOOR LIGHTING IMPROVEMENT SOCIETY (SOLIS). SOLIS aims to educate and inform about quality outdoor lighting and its benefits. We also lobby councils, government and other bodies to promote good lighting practice. SOLIS meetings are held third Monday night of each month at Sydney Observatory. Individual membership is $20 pa. Donations are also welcome. Cheques payable to “SOLIS c/- NSAS”, PO Box 214, West Ryde 2114. Email: tpeters<at>pip.elm.mq.edu.au 96  Silicon Chip Microgram Computers..............3,73 RobotOz......................................73 R.T.N............................................73 SC Computer Omnibus...............11 Silicon Chip Bookshop........... 86-87 Silicon Chip Subscriptions...........53 Silvertone Electronics..................95 Telelink Communications.............73 Truscott’s Electronic World...........69 Zoom EFI Special......................IBC _____________________________ PC Boards Printed circuit boards for SILICON CHIP projects are made by: •  RCS Radio Pty Ltd, 651 Forest Rd, Bexley, NSW 2207. Phone (02) 9587 3491. •  Marday Services, PO Box 19-189, Avondale, Auckland, NZ. Phone (09) 828 5730. MORE FROM YOUR EFI CAR! Own an EFI car? Want to get the best from it? You’ll find all you need to know in this publication EFI TECH SPECIAL Here it is: a valuable collection of the best EFI features from ZOOM magazine, with all the tricks of the trade – and tricks the trade doesn’t know! Plus loads of do-it-yourself information to save you real $$$$ as well . . . HERE ARE JUST SOME OF THE CONTENTS . . . n Making Your EFI Car Go Harder n Building A Mixture Meter n D-I-Y Head Jobs n Fault Finding EFI Systems n $70 Boost Control For 23% More Grunt n All About Engine Management n Modifying Engine Management Systems n Water/Air Intercooling n How To Use A Multimeter n Wiring An Engine Transplant n And Much More including some Awesome Engines! AVAILABLE DIRECT FROM SILICON CHIP PUBLICATIONS PO BOX 139, COLLAROY NSW 2097 - $8.95 Inc GST & P&P To order your copy, call (02) 9979 5644 9-5 Mon-Fri with your credit card details! FROM THE PUBLISHERS OF “SILICON CHIP”