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Windows 98 - Avoiding The Install Traps SILICON CHIP NOVEMBER 1998 $ 50* 5 ISSN 1030-2662 11 NZ $ 6 50 INCL GST PRINT POST APPROVED - PP255003/01272 9 771030 266001 www.siliconchip.com.au PROJECTS TO BUILD - SERVICING - COMPUTERS - VINTAGE RADIO - RADIO CONTROL Make it for your Christmas tree: MICROPROCESSOR CONTROLLED STAR DECORATION Plus: Poker Machine Turbo Timer for Cars Three Radio Microphones November 1998  1 SILICON CHIP If you are seeing a blank page here, it is more than likely that it contained advertising which is now out of date and the advertiser has requested that the page be removed to prevent misunderstandings.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 Contents Vol.11, No.11; November 1998 FEATURES   4  Silicon Chip On The WWW Log on to Silicon Chip’s web site – by Ross Tester   8  Beyond The Basic Network Setting up a LAN using TCP/IP – by Bob Dyball 86  Electric Lighting; Pt.9 The basics of luminaires – by Julian Edgar PROJECTS TO BUILD Silicon Chip On The WWW – Page 4. 18  The Christmas Star Simple microprocessor-controlled decoration – by Les Grant 24  Turbo Timer For Your Car Lets the turbo cool down to safe temperatures – by John Clarke 36  Build Your Own Poker Machine Gamble without losing your shirt – by Andersson Nguyen 54  An FM Transmitter For Musicians Three radio microphones to build from one kit – by Branco Justic 66  Lab Quality AC Millivoltmeter; Pt.2 A Turbo Timer For Your Car – Page 24 Full construction details plus calibration – by John Clarke SPECIAL COLUMNS 30  Serviceman’s Log Big tellys, PCs and car computers – by the TV Serviceman 63  Radio Control A mixer module for F3B glider operations, Pt.1 – by Bob Young 78  Vintage Radio Improving AM broadcast reception, Pt.1 – by Rodney Champness Build Your Own Poker Machine – Page 36 81  Computer Bits Windows 98: how to clean install the upgrade version – by Greg Swain DEPARTMENTS   2  Publisher’s Letter 44  Order Form 53 Satellite Watch 58  Circuit Notebook 91  Ask Silicon Chip 93  Notes & Errata 94 Market Centre 96  Advertising Index FM Transmitters For Musicians – Page 54 November 1998  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.) Robert Flynn Ross Tester Rick Walters Reader Services Ann Jenkinson Advertising Manager Brendon Sheridan Phone (03) 9720 9198 Mobile 0416 009 217 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: $59 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 and maximum * Recommended price only. 2  Silicon Chip It is time to start employing more people Now that the Federal election is out of the way, maybe the Government can start seriously addressing Australia’s major problem: unemployment. We have gone too far down the road to “lean and mean” corporations, both government and private. It is time to reassess what all the huge job losses over the last ten years or so have meant for Australians. For those who have lost their jobs it has generally meant a fringe existence, wondering if they will ever have a proper job again and a great loss of self-confidence. For the wider community, it has meant rising crime, drug abuse and suicides. And it has also led to a general lowering of service standards right across government and private enterprise. This has been typified by the recent debacles of Sydney’s water parasite infestation, Victoria’s loss of gas supplies and Brisbane’s electricity blackouts. The fact is that in most gov­ernment utilities and in many of the larger companies, there are just not enough people, particularly qualified people, to do the job. Maintenance is not being done and overall safety levels are dropping. Companies and government organisations simply cannot provide the service levels that used to be delivered. If you need convincing, just try phoning any large or medium sized company or government body. You will no doubt need to phone a 131 number and then you will be placed in an intermi­nable queue. “Your call is important to us, please hold and etc, etc”, is the drivel you have to put up with in between listening to some irritating music-on-hold. And then when you do finally get to talk to a human, you will often find that he/she hasn’t a clue what you’re talking about and there is no guarantee that your request/ report or whatever will be acted upon. These companies and organisations are clearly not attempt­ing to provide proper levels of service and ultimately, they will suffer in the long term. So will their customers. The situation is now so bad that it is a real pleasure to phone a company or organisation and find that not only do they answer the phone quickly but a real person answers. If they are able to quickly help, then so much the better. Thankfully, in the electronics business, most companies still have real people answering the phones and some provide very good levels of serv­ice. You can only do that if you have adequate numbers of people who are trained to do their jobs. For the future, the Government must actively start encour­aging companies to employ more people. The Government likes to talk about how many jobs it has created over a period. That is nonsense; governments don’t create jobs, they destroy them. For their part, companies need to review their long-term strategy (if they have one). They need to realise once more that the only way to grow and make more profits is to invest heavily in their people and ultimately, to employ more people. And many Australians need to realise that profit is not a dirty word. If companies don’t make profits, they can’t afford to employ people. Leo Simpson M croGram Computers Internal UPS & Power Supply It’s not just a UPS but also a 300W power supply. The UPS is actually built into a standard size power supply and the batteries and front panel occupy a 5.25in drive bay. The UPS is rated at 500VA. Apart from power failure, the UPS also protects against over voltage, under voltage, overload & DC short circuit. The unit is available in two sizes - PS/2 or ATX. Optional software provides for automatic shutdown. Cat. No. 8498 UPS / PS (PS/2) Int 500VA/300W Cat. No. 8588 UPS / PS (ATX) Int 500VA/300W Cat. No. 8499 UPS / PS Internal RUPS S’ware $499 $439 $99 Enhanced Network Cable Tester Tests a range of Modular cables including 10Base-T (Category 3-5), as well as AT&T 258A, EIA/TIA and Token Ring. Includes a remote terminator. Cat. 11516 Enhanced Network Cable Tester Compact 81 Key Infra Keyboard R ed Keyboard IR Cordless $149 PCMCIA Bar Code Wand Cat. No. 3374 Hard Drive Recovery Card $149 PCMCIA Card Drive for Desktop PC UPS 500VA UPS 750VA UPS 1500VA UPS 2000VA Cat. No. 8591 $360 $470 $1120 $3060 Dual Exhaust Fans Mouse Tablet The Bar Code Wand lets you use your handheld PC to collect bar code data directly into any Windows CE application. When you move the wand across a bar code, Windows CE programs behave as though you typed the data in, eliminating the need for special programming. You can replace expensive, dedicated data collection terminals with your H/PC and perform an unlimited variety of computational tasks right at the point of data capture. Cat. 8672 Hard Drive Recovery Card Ou high performance PCMCIA Card Drive provides two front-access sockets on a 3.5" front bay and supports one Type III PC Card and one Type I or II PC card Cat. 3359 Year 2000 BIOS Card $129 simultaneously. The drive supports synchronous & asynchroUninterruptable Power Supplies nous PC cards as well as all major operating systems. Whether you require a line interactive or true on-line Cat. 6121 PCMCIA Card Drive for Desktop PC $209 UPS, we have the right one for you. From entry level UPS’s PCMCIA Card Drive & FDD for stand alone PC’s to intelli- Replace your existing floppy drive with a combinagent microprocessor con- tion FDD/PC Card Drive. It’s a standard 1.44MB trolled UPS’s for professional floppy drive and a Type III PCMCIA socket but is the high performance file server same physical size as a floppy disk drive. Cat. 6458 PCMCIA Card Drive & FDD $399 applications. This infra red compact keyboard features 86 keys with Win 95 104 key functionality. It features membrane keyswitch with tactile feedback, an effective operating angle of 360 degrees over a distance of 7 metres and low power consumption with high efficiency power management for long life operation. Two buttons at the upper left serve as clicking devices. No. 8645 The infra red receiver has a 6-pin PS/2 mouse connector Cat. Cat. No. 8646 and standard 5-pin keyboard connector. Cat. No. 8574 Cat. 8655 Over 180 courses on offer FORMAT, FDISK, VIRUS......OOPS! Recover data from your hard drive after FDISK, $129. FORMAT or DELETE commands or even after virus attacks. Supports DOS, Windows 3.x, Windows 95, OS/2 and Windows NT. Even Pentium motherboards are not immune to the Year 2000 bug! - so don’t leave it ‘till it’s too late. The Year 2000 BIOS Card solves the problem of progression from 1999 to 2000 as well as 21st century leap years. It is an 8-bit card which provides $69 year 2000 support for motherboards with a BIOS which only stores the year with two digits. i.e. 97 instead of 1997. When desk space is at a premium an 80 key keyboard with full 101 key functionality will come in handy. It has dimensions of only 297(W) x 152(L) x 30(D) mm. A number of courses are “Microsoft Certified Professional - Approved Study Guides” *Full details at www.tol.com.au Year 2000 BIOS Card Compact Keyboard Cat. No. 8238 Web-Based Training from $9.95 per month* Learn about Microsoft Office, Word, Access, Excel, Windows 95, FrontPage, C++, HTML, Internet Explorer, Windows NT and more! PCMCIA Bar Code Wand $1015 The Mouse Tablet 604 is an extraordinary input device that allows you to choose between an easy-to-use, high resolution, trackball-free mouse or an absolutely precise stylus pen. Both pointing devices are implemented with cutting-edge electromagnetic technology, and have a resolution up to 4064 LPI. The three-button stylus pen provides pinpoint accuracy and writing, drawing & painting abilities. Bundled software includes NetProbe (a built-in Internet direct access utility), PenSurfer and PenGuard. Cat. 8676 Mouse Tablet $159 Two products to keep your computer and your hard drive cool! Dissipate heat with dual exhaust fans attached to a plenum to exhaust hot air from inside the computer. Reduce the possibility of data loss due to your HD overheating with dual fans attached to a ventillated face plate. It will effectively dissipate heat from the HDD & significantly lower internal temperatures. Cat. No. 8564 Cat. No. 8420 E & OE Hard Drive Cooling Fans Dual Exhaust Fans All prices include sales tax $49 $45 MICROGRAM 1198 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 We welcome Bankcard Mastercard VISA Amex Unit 1, 14 Bon Mace Close, Berkeley Vale NSW 2261 FreeFax 1 800 625 777 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 November 1998  3 SILICON CHIP This article has been removed because the information it contained was out of date. Please visit our new web site at: www.siliconchip.com.au 4  Silicon Chip SILICON CHIP This article has been removed because the information it contained was out of date. Please visit our new web site at: www.siliconchip.com.au November 1998  5 SILICON CHIP This article has been removed because the information it contained was out of date. Please visit our new web site at: www.siliconchip.com.au 6  Silicon Chip SILICON CHIP This article has been removed because the information it contained was out of date. Please visit our new web site at: www.siliconchip.com.au November 1998  7 COMPUTERS: Networking for the home or small office Beyond The Basic Network Setting up a LAN using TCP/IP Are you getting the best out of your current PC? You can get even more out of it by networking it to one of your older PCs which can then be used as a print server or fax server while you carry on with other tasks. By BOB DYBALL Not too long ago, a “LAN” or “Local Area Network” meant having an expensive server and a number of dumb terminals. Although it can still mean this, a LAN is now usually a “peer to peer” network, consisting of two or 8  Silicon Chip more PCs which can act as both servers and clients. A server no longer has to be expensive either. In fact, you can use a previously retired 386 or 486 machine for many tasks, thereby freeing your main PC for more useful jobs. Whether you are in a small office or just at home, take a look at what networking can do for you. For example, a LAN will allow you to: •  share a printer; •  share files or programs; •  share a modem for fax or Internet access; •  set up a small web server and Intranet; •  study networking to further your education; and •  play games against other family members and friends. Obviously there are many different things that you can do but where should you start? The first thing to do is take a look at your needs and the resources you have available. For example, let’s say that you have a small office with three or four people and you’ve recently upgraded your last remaining 486 PC to a Pentium machine. Before tossing the old 486 onto the scrapheap, consider putting it to use as say a fax server and printer server. That way, everyone in the office can easily print to the same printer and have access to a modem, provided that they’re part of the network. On the home front, you may have a laptop that’s used for work plus a fairly new PC that’s used by the kids. In addition, you may also have an old 386 machine that’s been retired, or you know where to acquire one quite cheaply. Now here’s the problem: both you and the children need to get onto the net but you’d like to avoid having extra phone lines (and modems). You are also concerned about what they might see on the net. A LAN can help here and, with the right software, pro­vide a “gateway” to the net that is safe and convenient. And you will only need one modem for everyone. Setting up a LAN involves installing a network card in each PC involved. For a laptop, the network card might be a plug-in PCMCIA or PC card device, while for older PCs it will be a 16-bit ISA network card. Pentium or later machines can be fitted with either ISA or PCI network cards. Networking options Two main types of LANs are commonly used in small “peer to peer” systems. The cheapest to set up is known as 10Base2. It uses RG-58 coaxial cable and network cards that have BNC connec­tors fitted. The PCs are simply connected together in daisy-chain fashion (see Fig.1), with the cable run via T-connectors on each PC. The two ends of the chain are fitted with 50-ohm terminators. The other common system is known as 10BaseT. This type of system requires a “hub”, which provides a central connection point for the network – see Fig.2. It uses flat twisted-pair cable fitted at either end with RJ-45 connectors (similar to telephone connectors). A hub costs $50 or more for a small 5-port model but you can also buy 8-port and 16-port hubs if required. Be- Fig.1: a 10Base2 (thin Ethernet) network uses coaxial cable and network cards that have BNC connec­tors fitted. The PCs are connected together in daisy-chain fashion, with the cable run via T-connectors on each PC. The two ends of the chain are fitted with 50-ohm terminators. Fig.2 the 10BaseT system requires a “hub”, which provides a central connection point for the network. It uses flat twisted-pair cable fitted at either end with RJ-45 connectors (similar to telephone connectors). cause a hub is not needed for 10Base2, many home users opt for this type of network. It’s cheaper but a break anywhere in the cable usually means that the whole network stops working. In an office, where reliability is more important, the 10BaseT network is often used. It’s advantage is that one faulty cable, say from one user to the hub, doesn’t bring the whole network down. Only the user with the faulty cable will be affect­ed. A look at the diagram for 10Base2 (Fig.1) shows why a single break in the cable can affect everyone on the network. Occasionally, users in each of the remaining segments of cable can “talk” to each other but the absence of a terminator at one end of the cable segment makes this very unlikely. If you do decide to use 10Base2, look for a “combo” net­work card. These have both 10BaseT and 10Base2 connectors. This will allow you to change to a 10BaseT network later on, if you Table 1: 10Base2 vs. 10BaseT 10B ase2 Advantages Disadvantages Generally cheaper to set up. A cable break anywhere generally brings down the whole network. Ideal for use where Inconvenient to users are spread install where users out i n a l i ne. are in a "star" arrangement. Slower than 10BaseT, since network cards are limited to halfduplex operation. 10B aseT Advantages Disadvantages More reliable - a break in a cable affects only one user. Ideal for use where users are clustered together in one area and the hub can be centrally located. Faster than 10Base2 since the network cards can use full duplex operation. More expensive because a central hub is needed to connect all users. Messy and expensive to cable where the users are all located in a l ong l i ne. November 1998  9 Add button, select Protocol, click Add again, select Microsoft, select TCP/IP and click OK – see Fig.3. Once you have installed the networking protocol(s), select the TCP/IP protocol for your network card (at the Configuration tab of the Network applet) and click the Properties button. You can now set up your IP address, as shown in Fig.4. Note that the IP address set here is “bound” to the LAN card and is non-routable. In other words, it is purposely select­ed so that it is ignored if you connect to the real Internet, in the outside world. IP addresses Fig.3: check this dialog box to ensure that the TCP/IP protocol is installed for your network card (not just for a DialUp Adapter). If it hasn’t been installed, follow the procedure in the text. Fig.4: you set up the TCP/IP addresses using this dialog box. Each computer on the network must have its own address and these must also be entered in a simple text file named LMHOSTS – see text. wish to expand the network. In fact, it’s difficult to buy straight 10Base2 network cards these days. PCMCIA cards for laptops tend to be a rather expensive. However, you should be able to get a reasonable PCI or ISA combo network card for less than $40.00 set up your own intra­net and experiment with a web server, then you will have to use the TCP/IP networking protocol. In case you’re wondering, TCP/IP stands for “Transmission Control Protocol/Internet Protocol” and was originally devised by Novell. Although it might initially appear rather mysterious, TCP/IP isn’t all that hard to get going. The first step is to install the networking protocol and you do that via the Network applet in Control Panel. The procedure is as follows: load the applet, click the NOS: Network Operating System Prior to Windows for Workgroups 3.11, you didn’t have too many choices when it came to the network operating system (NOS). You either used Lantastic or Novell Personal Netware for a “peer-to-peer” system, or you used a Novell server in a client/server arrangement. None of these choices were cheap and nor were they all that easy to set up. This situation changed with Windows for Workgroups 3.11, which featured an inbuilt peer-to-peer network operating system (NOS). Windows 95/98 and Windows NT also include built-in network­ing capabilities. Identification Network protocols Usually, you would set up a small network using either the NetBEUI or IPX/SPX protocols. Indeed, if you intend using your old PC up as a file server, print server and/or a fax server, these network protocols are likely all you’ll need. On the other hand, if you’d like to 10  Silicon Chip How do you know which number you can use. Well, the Inter­net Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for “private internets” (ie, intranets): (1) 10.0.0.0 to 10.255.255.255 (2) 172.16.0.0 to 172.31.255.255 (3) 192.168.0.0 to 192.168.255.255 For this and further details on IP addressing, see refer­ence document RFC1918 at: http://ucnet.canberra.edu.au/RFC/ rfc/rfc1918.html The special IP address 127.0.0.1 refers to the PC itself. This is useful to know in some cases; eg, if you have a program that uses TCP/IP to “talk” to another program on the same PC. Because these TCP/IP addresses are non-routable, it means that the Internet can not normally “see” past the PC that has the modem. In other words, it cannot “see” the other computers on the network (unless you have special software acting as a go-between). Nor can the rest of your intranet normally access the Internet through the PC with the modem. Of course, there are ways to provide this access and this involves using a “gateway” or “router”. Fig.5: each computer on the network must be given a unique Computer name but all machines must have the same Workgroup name. Having set up the IP addresses, you need to uniquely identify each computer on the network. You do that by clicking the Identification tab at Fig.3 to bring up the dialog box shown in Fig.5. Each computer must be given a unique “Computer name” but the same Workgroup name must be used for all machines on the network. Having done this, click the “File and Print Sharing” button and select Fig.5: Example LMHOSTS File 192.168.0.10   Anne 192.168.0.20   John 192.168.0.30   Server 192.168.0.40   Workstation whether you wish to share your files and/or a printer. Road maps for TCP/IP: LMHOSTS & DNS In simple terms, packets of information sent via the Inter­ net using TCP/IP find their way around using a Domain Name Server (DNS). These are like road maps. Usually, it’s not worth the trouble setting up a DNS to translate names to IP addresses for a small intranet (and in any case, you need NT Server). Instead, on a small network, IP addresses are best allocated using a simple text file called LMHOSTS. On large networks with NT Server, you can use WINS or DHCP. The LMHOSTS file contains a list of the names of the various PCs on the intranet and their corresponding IP addresses. A sample file called LMHOSTS.SAM should be in the C:\ WINDOWS directory. You simply copy this to the filename LMHOSTS in the same directory, strip out the comments (for speed of access by the PC) and edit it to include the details of the PCs in your system. When the PC is restarted, your software will be able to “see” other PCs on the network (programs permitting) which use the TCP/IP protocol. The accompanying panel (Fig.6) shows an example LMHOSTS text file after editing. Note that the various names must agree with the names assigned to each computer – see Fig.5. Having set up your TCP/IP network, you can put it to work. Let’s take a closer look at some of the more useful functions. File server It is much simpler to back up one directory than many direc­tories on different PCs. Storing your documents on a shared directory on a network drive means that you need only back up one directory branch to save copies of everyone’s work. If you have invested in a ZIP drive or CD-ROM writer, this can be cen- Fig.7: you can share a drive (or folder) by right clicking it in the Explorer, then clicking the Sharing option from the drop-down list and selecting the various options in this dialog box. Fig.8: to share a printer, double click printers in My Computer or in the Control Panel (of the print server), right click the printer and select the Sharing tab. trally placed to allow easy backup and access. To share a drive, right click it in the Explorer (or in My Computer), click Sharing and click the “Shared As” option – see Fig.7. Type in the share name in the space provided, then click “Full” for the Access Type. You can also set a password if you wish but don’t do this unless necessary because it can be a nuisance. Windows 98. You will need to get a third party product, such as I-Share from Artisoft, if you wish to share a modem across the network. Print server Sharing a printer is just as easy as sharing files across the network. Under Windows 95 or 98, on the printer “server”, click Start, Settings, Control Panel, then double click Printers. Now right click the printer, select the Sharing tab and you’re all but there – see Fig.8. Shared modem access Unfortunately, sharing a modem (eg, for bulletin board access) is not something that’s built into Windows for Workgroups 3.11, Windows 95 or Fig.9: don’t forget to click the “File and Print Sharing” button so that you can share your files and/or printers. Shared Internet access Unfortunately, you also need extra software to provide shared Internet access across a network using one dial-up modem – unless you have one of the big guns, that is (eg, Windows NT4 Server or Microsoft Proxy Server 2.0). However, this isn’t difficult if you have the right program. There are a number of commercial packages for Windows and these fall into one of two categories. Some programs simply act as “routers”, re-routing Internet traffic appropriately. Others have a complete firewall system built in, including password access, and may even include a “proxy server” to cache web pages already recently accessed. A proxy server saves time and money when browsing the Inter­net. In an office or home, you might like to restrict the web­sites that are available to different users. Some cheap shareware packages even allow you to restrict the type of access – eg, allow­ing email access only, with full access from 4-5pm daily. Intranet web server Why on Earth would you want your own web server and web pages, on November 1998  11 to try it before deciding to buy. This program features proxy caching of web pages, a firewall option and the ability to create user profiles. This last feature can be used to prevent users on one PC from accessing certain Internet protocols at various times, while giving complete access from another PC. CProxy is available for download from www.computalynx.co.uk or from www.winfiles.com/apps/98/ servers-proxy.html You will also find dozens of other routers and proxy servers at the latter site. Fig.10: proxy server software can be used to restrict access to certain Internet protocols at various times of the day and to prevent access to certain sites. A good shareware program is Computalynx CProxy V3.1 which comes with a timer, allowing you to try it before deciding to buy. your own LAN as part of an intranet? Well, an intranet can have many advantages, particularly in large organisations that need to disseminate data. An Intranet is basically a cutdown version of the Internet and you can duplicate many of its functions. If you wish to develop web pages at home, for practice, fun or profit, you can easily set up a server using Microsoft’s Personal Web Server software. This is supplied with the Front-Page 98 package and can run under Windows 95/98, handling up to 30 simultaneous requests. Users of Windows 95 can use the Windows NT Option Pack 4 (yes the NT option pack), provided it’s the Windows 95 version. There are three versions – one for NT 4 Server, one for NT4 Workstation and one for Windows 95. This option pack is available from http://backoffice. microsoft. com/downtrial/default.asp by following the links. Windows 98 users will find this software on the Windows 98 CD-ROM in the \ADD-ONS\PWS directory. This latest Personal Web Server also supports .asp web pages (Active server Pages), there­by providing an ideal place to test out web site designs without going to the expense of a fullblown Windows NT 4 Server and Web Server system. A number of other shareware or freeware web servers are also available. Check out the following two 12  Silicon Chip Mail gateways web sites for just a few of the many programs that can be downloaded: (1) http://www.winfiles.com (2) http://www.download.com If you are looking for a fully-featured web server, take a look at O’Reilly’s Web Site Pro – see http:// www.ora.com. This excellent web server also features support for Active Server Pages (.asp). A mature open standard, .asp web pages allow serv­ er-side scripting which can be very useful. As an example, it can allow your site to extract data, on the fly, from an ODBC data source and make up the new web page as it goes. With your own web server you can easily put confi­dential company information online internally for sales or other sup­port staff. With .asp web pages, it’s possible to read and write to database files and even create an accounts system, all through web pages displayed on standard web browsers. Proxy servers and safe browsing for kids If you want to stop the kids from browsing sites they shouldn’t or simply restrict their access times, a shareware proxy/firewall package is the answer. This sort of software is not only useful in the home but can also be used in a small business. One such shareware program is Computalynx CProxy V3.1 which comes with a timer, allowing you Another useful function to add into your server might be a mail server or mail gateway. Again there are a number of share­ware options available. You will need to consider how you will handle multiple user names or if you wish to stay with the one username (usually your account name). For example, let’s say that John Smith and Jane Smith would like to have their email delivered under their own names. To do this, you could arrange to have two separate dial-up accounts, with each person independently logging onto the ISP (eg, as johns<at>xyz.com.au and janes<at> xyz. com.au). However, this requires two separate calls and will attract two account fees as well. A better scheme, if your ISP allows it, is to have one log-on account (eg, smith<at>xyz.com.au) but then have separate mail accounts (johns<at>xyz. com.au and janes<at>xyz.com.au as before). Depending on the ISP, this shouldn’t cost much more that the normal charge. By using an email program that lets you set up multiple accounts, you can easily check both accounts with just one phone call. Another approach is to set up a permanent Internet feed for your server. Your server could then receive email direct instead of it going via your ISP. To do this you would have to register a suitable domain name (eg, smith.com.au) and arrange for a perma­nent connection, either phone or ISDN, to your ISP. Your ISP would then change their MX record (a mail exchange pointer) to redirect incoming mail to your mail server, instead of it going to their mail server SC for later download. Silicon Chip Bookshop SUBSCRIBE   AND GET   10% OFF SEE PAGE 44 Guide to Satellite TV Installation, Recept­ion & Repair. By Derek J. Stephen­son. First published 1991, reprinted 1997 (4th edition). This is a practical guide on the installation and servicing of satellite television equipment. The coverage of the subject is extensive, without excessive theory or mathematics. 383 pages, in hard cover at $55.00. Servicing Personal Computers By Michael Tooley. First published 1985. 4th edition 1994. Computers are prone to failure from a number of common causes & some that are not so common. This book sets out the principles & practice of computer servicing (including disc drives, printers & monitors), describes some of the latest software diagnostic routines & includes program listings. 387 pages in hard cover at $90.00. Video Scrambling & Descrambling For Satellite & Cable TV By Rudolf F. Graf & William Sheets. First pub­lished 1987. This is an easy-to-understand book for those who want to scramble and unscramble video signals for their own use or just want to learn about the techniques involved. It begins with the basic techniques, then details the theory of video encryption and decryption. It also provides schematics and details for several encoder and decoder projects, has a chapter of relevant semiconductor data sheets, covers three relevant US patents on the subject of scrambling and concludes with a chapter of technical data. 246 pages, in soft cover at $50.00. The Art of Linear Electronics By John Linsley Hood. Pub­lished 1993. This is a practical handbook from one of the world’s most prolific audio designers, with many of his designs having been published in English technical magazines over the years. A great many practical circuits are featured – a must for anyone inter­ ested in audio design. 336 pages, in paperback at $70.00. Digital Audio & Compact Disc Technology Produced by the Sony Service Centre (Europe). 3rd edition, published 1995. Prepared by Sony’s technical staff, this is the best book on compact disc technology that we have ever come across. It covers digital audio in depth, including PCM adapters, the Video8 PCM format and R-DAT. If you want to understand digital audio, you need this reference book. 305 pages, in paperback at $90.00. Surface Mount Technology By Rudolph Strauss. First pub­lished 1994. This book will provide informative reading for anyone considering the assembly of PC boards with surface mounted devices. Includes chapters on wave soldering, reflow­soldering, component placement, cleaning & quality control. 361 pages, in hard cover at $99.00. Radio Frequency Transistors Principles & Practical Applications. By Norm Dye & Helge Granberg. Published 1993. This book strips away the mysteries of RF circuit design. Written by two Motorola engineers, it looks at RF transistor fundamentals before moving on to specific design examples; eg, amplifiers, oscillators and pulsed power systems. Also included are chapters on filtering, impedance matching & CAD. 235 pages, in hard cover at $95.00. Guide to TV & Video Technology By Eugene Trundle. First pub­lished 1988. Second edition 1996. Eugene Trundle has written for many years in Television magazine and his latest book is right up date on TV and video technology. 382 pages, in paperback, at $55.00. Electronics Engineer’s Reference Book Edited by F. F. Mazda. First published 1989. 6th edition. This just has to be the best refer­ ence book available for electronics engineers. Provides expert coverage of Your Name__________________________________________________ PLEASE PRINT Address____________________________________________________ _____________________________________Postcode_____________ Daytime Phone No.______________________Total Price $A _________ ❏ Cheque/Money Order  ❏ Bankcard  ❏ Visa Card  ❏ MasterCard Card No. Signature_________________________ Card expiry date_____/______ Return 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. all aspects of electronics in five parts: techniques, physical phenomena, material & components, electronic design, and applications. The sixth edition has been expanded to include chapters on surface mount technology, hardware & software design, semi­-custom electronics & data communications. 63 chapters, soft cover at $160.00. Audio Electronics By John Linsley Hood. Pub­lished 1995. This book is for anyone involved in designing, adapting and using analog and digital audio equipment. Covers tape recording, tuners & radio receivers, preamplifiers, voltage amplifiers, power amplifiers, the compact disc & digital audio, test & measurement, loudspeaker crossover systems and power supplies. 351 pages, in soft cover at $75.00. Understanding Telephone Electronics By Stephen J. Bigelow. Third edition published 1997 by Butterworth-Heinemann. This is 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 techniques (modems & fax machines) and much more. Ideal for students. 367 pages, in soft cover at $55.00. ✓ Title Price ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ ❏ Guide to Satellite TV $55.00 Servicing Personal Computers $90.00 Video Scrambling & Descrambling $50.00 The Ar t Of Linear Electronics $70.00 Digital Audio & Compact Disc Technology $90.00 Surface Mount Technology $99.00 Radio Frequency Transistors $95.00 Guide to TV & Video Technology $55.00 Electronic Engineer's Reference Book $160.00 Audio Electronics $75.00 Understanding Telephone Electronics $55.00 Postage: add $5.00 per book. Orders over $100 are post free within Australia. NZ add $10.00 per book; elsewhere add $15 per book. TOTAL $A November 1998  13 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 The Christmas Star What’s this? A Christmas project in November? Well, we were so taken with this cute little project that we just had to run it this month so that readers would have plenty of time to build it for Christmas. It’s a Christmas “star” which lights up its LEDs in a seemingly endless variety of patterns. Build it to add that “something different” to your Christmas tree. Or put it in the front window to impress the neighbours! The PC board has just one IC to drive 30 LEDs which are arrayed in a five-pointed star. But we can’t show you what the star looks like since the LEDs constantly flash in lots of different ways. Sometimes the LED “points” of the star will flash, then they will rotate, then reverse direction, then the whole star lights up from the centre outwards and so on. The circuit uses just one IC and yet the range of flashing patterns seems endless, although it does actually repeat the sequence after a minute or so. With such a simple circuit producing such a variety of patterns the conclusion is inevitable. Yes, the IC is a microprocessor otherwise it would not be able to produce such a huge variety. The PC board is five-sided and is quite small, suitable for mounting at the top of your Christmas tree if you want. It is powered by a 9V DC plugpack and has an onboard 5V regulator. The microprocessor is an Atmel AT89C2051, a relatively recent derivative of the very common 8051. It comes in a 20-pin plastic package and contains 2K 18  Silicon Chip bytes of program memory, 128 bytes of RAM, 15 programmable I/O lines, on-chip oscillator, two 16-bit counter/timers, six interrupt sources and a full duplex serial port (UART). This all sounds very much like a small 8051 until we add that the program memory is re-programmable Flash with 1000 erase/write cycles, the oscillator runs to 24MHz (double that of the original 8051), the I/O pins can sink 20mA for directly driving LEDs and two I/O pins are connected to an on-chip analog comparator. In other words, it is a somewhat souped-up 8051 and it can drive the LEDs direct, without any other circuit components. This project started just before last Christmas when my daughters asked “Why don’t we have any flashing Christmas tree lights?” So, while they were out shopping, my son and I grabbed a dozen LEDs, some ribbon cable and a microcontroller. While my son wired up the LEDs, I wrote some simple software. It was all installed and running when they came home after spending all my money. That’s why we didn’t have lights before... The smiles on their faces made it all worthwhile! I then resolved to do by LES GRANT* something better for this coming Christmas. And here is the result. Why use a Microcontroller? Using a PC’s parallel port to control external devices is a popular approach these days but I certainly couldn’t afford to tie up a PC for the few weeks leading up to Christmas just to flash a few LEDs; just think of the power bill to run a few LEDs in this way! So, why not use a small microcontroller? They are cheap and easy to use and if the design doesn’t work first time, you simply re-program it. So that is what I did. As already mentioned, the hardware is the Atmel '2051 micro. To make it start thinking, we need a reset circuit and this simply consists of the 10µF capacitor (C7) connected to pin 1. The reset function works because the capacitor briefly holds pin 1 high when power is first applied. Then the capacitor charges up and this causes pin 1 to be pulled to 0V. When the power is switched off, diode D2 forces this capacitor to discharge quickly, ready for the next time power is applied. To set how fast the micro thinks, we need a 12MHz crystal X1 (in fact we used 11.0592MHz) and associated capacitors C1 and C2, connected to pins 4 & 5. Note that the crystal could be replaced by a 12MHz ceramic resonator. This allows the ‘2051 to execute an instruction every 1 or 2µs. As you can see from the circuit of Fig.1, the 30 LEDs are connected in an X-Y matrix. Why 30 LEDs? Engineering is full of trade-offs or com- promises. I wanted a 5-pointed star so the number had to be divisible by 5. For aesthetic reasons, we need an even number of LEDs per point. Six LEDs per point looked “about right”. The next step up would have been 40 LEDs which would have required 13 I/O pins to drive them and a more complicated PC board. We can drive 30 LEDs from only 11 I/O pins using a process called multiplexing. The appropriate combination of LEDs in a column is switched on for a short time (about 2ms in this case). This process is repeated for each column in turn, taking 10ms for a full cycle. Provided the multiplexing is done quickly enough, the persistence of the human eye “fills in the gaps” and we see any combination of LEDs on without any flicker. The minimum practical multiplexing frequency is about 100Hz which is the frequency used by the star. Fig.1: the micro drives the 30 LEDs in 5 x 6 matrix, with 5 colums and 6 rows. There is provision for an optional EEPROM which will store extra patterns in the future. November 1998  19 Ideally, the LEDs should be high brightness types for best effect and in an ideal world would be matched for brightness. Maybe that's going a tad too far . . . The power supply uses the ubiquitous 7805 3-terminal regulator with 0.1µF bypass capacitors at its input and output. Diode D1 provides reverse polarity protection so that you can’t blow up the circuit if the DC supply is connected the wrong way around. The maximum current drawn by the star is about 150mA with all LEDs on but is less than about 50mA for most patterns. The maximum temperature rise of the 7805 when the star is run from a typical 9V DC unregulated plug-pack is about 30°C which is quite acceptable. If run from a 12V DC unregulated plug-pack it gets warmer and therefore should be provided with a small heatsink. Star software TWINKLE, TWINKLE little star. How I wonder how you are. . . Bet you never saw a star twinkle like this one. Its on-board micro drives the LEDs in all sorts of patterns to light up the star. Fig.2: the component overlay, Make sure that you insert all the LEDs correctly: the cathode, or flat side, is oriented to the right in all cases. Don’t insert the micro until you’ve done a voltage check on the board (see text). 20  Silicon Chip In the spirit of Christmas, the basic source code is available free (you may download it from the SILICON CHIP Web site – www.siliconchip.com. au). An extended version that uses the EEPROM for storage is available at minimal cost from Grantronics Pty Ltd. The software was written in C language using the low cost Dunfield Development Systems Micro/C compiler. There is nothing particularly “smart” or “tricky” about the software – it was written to be easy to understand and to encourage use of small micros. Consequently, there are no interrupt routines and no use of the counter/timers, the UART or the comparator although Micro/C can make use of these resources. The software is table driven. This means that the display patterns and sequences are determined by data stored in a table (an array of bytes). There is a simple interpreter that scans through the table to perform the specified operations. The defined byte values are listed in Table 1. Note that there are quite a few undefined values so future expansion is possible. Putting it together Assembly is quite straight forward. You will need a soldering iron with Byte value or range 01 to 30 (0x01 to 0x1e) 33 to 62 (0x21 to 0x3e) 64 (0x40) 65 to 79 (0x41 to 0x4f) 128 (0x80) 129 to 191 (0x81 to 0xbf) 253 (0xfd) 254 (0xfe) 255 (0xff) Operation Turn on LED 1 to 30 Turn off LED 1 to 30 (LED number = byte – 32) Go back to byte after loop start Loop start, count = byte – 64 Delay (use last delay count), each count = 10ms Delay, count = byte – 128, each count = 10ms All LEDs on All LEDs off End of table a fine tip, preferably temperature controlled to about 600°F or 320°C. The first step is to carefully check for shorts between tracks and broken tracks. Fit the smallest parts first, the wire links, followed by the resistors and diodes. Next, fit the crystal (or resonator) and an IC socket for the micro. Then install the transistors, capacitors and LEDs. Pay particular attention to the orientation of the LEDs – they don’t work when installed backwards! Finally, install the 3-terminal regulator and the 2.1mm DC power socket. Don’t insert the micro into its socket just yet. Do another close visual inspection, looking for solder bridges especially Fig.3: actual size artwork for the PC board. on the transistor pads. Then apply power and check for the presence of 5V between pin 20 (+) and pin 10 of the IC1 socket. If all is OK, remove power, plug in the micro (careful!) and apply power again. After a brief pause, the micro starts to do its thing and generates quite a range of patterns which then repeat after a while. At the time of writing, the patterns weren’t quite finalised but there is enough to entertain you. Everyone who saw the prototype thought that it was cute – or words to that effect. The two holes in the board near LED1 may be used to hang the star and the holes near SK1 may be used to secure the plugpack’s cable. Finally, the appearance of the star may be enhanced by placing a piece ELECTRONIC COMPONENTS & ACCESSORIES •  LARGE RANGE OF ICs, RESISTORS, CAPACITORS & OTHER COMPONENTS •  MAIL ORDERS WELCOME! CROYDON STORE ONLY ELECTRONIC DISPOSALS CLEARANCE! •  OPEN FRAME 240V INDUCTION MOTORS 600 WATT AND 900 WATT. 600 WATT - $15 EACH OR 10 FOR $100 900 WATT - $18 EACH OR 10 FOR $120 •  LARGE VARIETY OF DISPOSALS TRANSFORMERS AT GIVEAWAY PRICES! Croydon Ph (03) 9723 3860 Fax (03) 9725 9443 MilduraPh (03) 5023 8138 Fax (03) 5023 8511 M W OR A EL D IL C ER O M E TABLE 1 Truscott’s ELECTRONIC WORLD Pty Ltd ACN 069 935 397 30 Lacey St Croydon Vic 3136 24 Langtree Ave Mildura Vic 3500 SILICON CHIP This advertisment is out of date and has been removed to prevent confusion. November 1998  21 of red cellophane over the front. Parts List Fault finding 1 5-sided PC board, code 08211981 1 2.1mm DC connector (SK1) 1 crystal or ceramic resonator, approx. 12MHz (X1) 1 20-pin IC socket 1 9V DC 150mA plugpack, Jaycar MP-3003 or equivalent Semiconductors 1 AT89C2051 programmed microprocessor (IC1) 1 7805 regulator (REG1) 1 24C16 EEPROM (optional, enhanced version only) 30 red LEDs (LED1-LED30) 5 BC557 PNP transistor (Q1-Q5) 1 1N4002 power diode (D1) 1 1N4148 or 1N914 diode (D2) Resistors (0.25W, 5%) 5 470Ω 6 120Ω NS_16_8 PCB is a system conditioning card with 16 optically isolated inputs set-up for either 12V or 24V operation. The board provides 8 single pole, double throw relays with 10 Amp contact rating. KITS & CARDS NS_DC_DC is a step down converter with an input range 11 to 35V DC and an output of 5 volts DC at 5 Amps, with an output ripple of approx 150mV. There is an IN/OUT 50-way connector isolating the 5V and 12V+ &12V- rails of the PC power supply. This segregates PC’s power when working on prototypes. NSDC_DC1 module used with NS_DC_DC & NSDC_DC4 converters is a 5V to 12V(+/-) step- up converter. The board utilises 743 switch mode IC with 2 x 12V regulators, with output ripple of approx 200mV. NS_UTIL1 prototyping board has 1580 bread board holes access to any 3 groups (0 to 4) on the 50-way cable pinout. Power is available from the 50-way cable format 5 volts at 2 Amps & 12V+ 12V- at 1 Amp. There is provision for array resistors with either a ground or positive common connection. For brochure write to: Reply Paid 68, NORBITON SYSTEMS, PO Box 687, Rockingham WA 6968 http://www.users.bigpond.com/norbiton 22  Silicon Chip Where to buy a kit We understand that the complete Christmas Star kit will be available from all Jaycar Electronics stores from SC this month for $29.95 * Les Grant is the Engineering Director at Grantronics Pty Ltd, electronics design engineers. They can supply the programmed microprocessors for $10 plus $5 for packing and postage. Send remittances to Grantronics Pty Ltd, PO Box 275, Wentworthville, NSW 2145. Phone (02) 9896 7150. NORBITON SYSTEMS NS_LED PCB gives visual access to five groups (0 to 4) of the NS_PC1OX. There is a total of 40 status LEDs. The board offers a 25-way “D” type female socket. The lines are driven by 74244 ICs & configured as a parallel printer port. This socket gives access to printer port kits, eg, stepper motors, LCDs, direct digital synthesis. The future The star is still evolving. That is Capacitors 1 4.7µF 16VW electrolytic 3 0.1µF monolithic or MKT polyester 2 27pF ceramic NS_PC101 card for XT/AT/PCs allows access to 48 I/O lines. There are 5 groups (0 to 4) available on a de-facto industrial standard 50-way ribbon cable used in STEbus and VMEbus 19" rack mount control systems. The board uses 2 x 8255 ICs. Multiple boards can be used if more I/O lines are required. If the 5V DC is not present, check the applied power polarity. The centre pin of the 2.1mm plug (SK1) must be positive. Check that D1 is correctly fitted. Check the tracks from SK1 via D1 and the 7805 to IC1 for breaks or shorts. If one LED does not work, it may be inserted backwards or it may be shorted by a solder bridge between its pads. If one group of adjacent LEDs does not work, check the circuitry and soldering around the appropriate column drive transistor. If several individual LEDs do not work, check the corresponding row drive circuitry. Remember, faulty components are rare, soldering problems are common! part of the attraction of using a micro – it is so easy to change the behaviour by changing the software. And what about that optional EEPROM? Well, an enhanced version of the star will read its data from the EEPROM for much longer sequences. To check out the latest version of the software, log on to the Grantronics web-site at http://www.grantronics.com.au If you don’t have Internet access, send a stamped ($1) self-addressed envelope with an IBM format 3.5" disc to Grantronics and they will send you the current software files. We hope you have as much fun building the star and playing with the software as I did creating it. Enjoy! Protect Your Valuable Issues Silicon Chip Binders REAL VALUE AT   Heavy board covers with 2-tone green vinyl covering $12.95 PLUS P & P   Each binder holds up to 14 issues  SILICON CHIP logo printed in gold-coloured lettering on spine & cover Price: $A12.95 plus $A5 p&p each (Aust. only). Just fill in & mail the handy order form in this issue; or fax (02) 9979 6503; or ring (02) 9979 5644 & quote your credit card number. Store Address: 56 Renver Road, Clayton. Victoria 3168 Postal Address: Bag 620 Clayton South. Victoria 3169 Phone: (03) 9543 7877 Fax: (03) 9543 4871 Website: http://www.rocom.com.au CAR DASHBOARD SPEAKER HOME TELEPHONE * 10 memory index * 3 Direct memories * Last number redial * Indirect memory activator * Easycall facility NOW * Tone / Pulse switchable 30.00 * Adjustable ringer volume * Flip-top message pad * Storage cover * Optional wall mount * Removable coloured keypad inserts * Austel Approved $89.00 stock# 108-100 MOSFET BUK456-60A * 60V 51A 150W * TO-220 $7.90 NOW $2.50 Email: sales<at>rocom.com.au * Impedance: 4 ohm * Input: 3W * Side-swivel screw clamp (north-south) * Cable with 3mm mono jack * All metal construction * Front Grill NOW * Mounting screws $8.00 * NEC Brand * 55mm x 110mm x 65mm stock# 108-101 N-CHANNEL FET - BTS115A * 15A * Style: D2-PAK $19.50 NOW $1.20 $3.30 WANTED Lots of Bargain Hunters to join hundreds of other bargain hunters on our Mailing List. No experience necessary. Stable home or mailing address essential. Remuneration by way of Monthly and Weekly Specials. Send your details to the above address. N-CHANNEL FET - RFP4010L * 40A 100V * TO-220 * Harris Semiconductor $4.50 NOW $1.50 stock# 108-103 stock# 108-110 stock# 108-108 FLOPPY DRIVE CONVERTER SELF ADHESIVE RUBBER FEET DC - DC CONVERTER * 100 Per Pack * 20mm x 20mm x 7.5mm * Size of each block (in mm) $24.90 NOW $8.00 stock# 108-116 4 MEG EPROM (256x16) * M27C4002 - 10XFI * National Semiconductor * 40 Pin DIL $24.90 NOW $3.00 stock# 118-100 POWER LEAD * 1.8M Oval Style Power lead * For Audio / Video Applications $2.90 NOW $0.50 stock# 108-125 * Converts 3.5” floppy drive for use on laptops * 3.5" mounting kit for 2.5" drives * With mounting frame $24.50 $12.00 stock# 108-145 LM2925T VOLTAGE REGULATOR * Low dropout regulator * 5 Volt * Vi/o: 0.82V <at>0.75A * TO-220/5b NOW $0.40 $2.70 NOW $70.00 * Approx: 5/16" x 7/16" * Solder tab mount * Metal casing * Velvet mouthpiece covering * No Data $1.90 stock# 108-161 TELEPHONE CURLY CORD * 4-Pin 4-Way modular plug on both ends * For connecting your telephone handset to the base * Approx 1.5m lead (extended) NOW $1.50 $3.50 NOW $0.50 SUBWOOFER / BRIDGE ADAPTOR FOR 12V If you need an active subwoofer filter or amplifier bridging adaptor, but only have 12vdc power source available as is the case with car sound systems, this inexpensive adaptor box should be just the shot. It can be configured to perform either of these tasks, accepts input signal at either speaker or line levels and have frequency respose down to zero hertz, thanks to its DC-coupled singal path. NOW stock# 108-314 *250V 10A *Length: 1 metre *Brand: ICM * Colour: White * APPROVED NOW $0.50 stock# 108-343 BEGINNERS VARIABLE DUAL - RAIL POWER SUPPLY If you are just beginning in electronics, then you’ll properly baulk at building a mains operated power supply. This project uses a plugpack which means that you can make your own variable dual rail power supply without worrying about mains wiring. NOW $25.00 $16.00 $139.00 $3.90 stock# 118-101 stock# 108-126 SUBMINIATURE MICROPHONES 3 PIN IEC STRAIGHT LEAD KITS KITS KITS KITS A low cost RF oscillator design that is suitable for checking and aligning HF radios and other equipment operating between 350kHz and 30 MHz. Features digital frequency readout, the abilitly to provide either CW or modulated output and also audio and 1 MHz reference singals from auxiliary outputs at the rear. stock# 108-309 NOW $1.50 NOW stock# 108-133 RF TEST OSCILLATOR * Input: 12VDC * Output: 8.5VDC 800mA * 2.0mm plug $29.95 stock# 108-317 $39.95 GET ON OUR EMAIL LIST! Our Email Customers receive PRIORITY notification of HOT SPECIALS and ONE-OFF BARGAINS all at rock bottom prices! We regularly broadcast new surplus stock items and other super deals via email. So, if you have an email address, we want it!!! Is your car turbocharged? Lucky you! But wait – literally: you really should hang about at the end of each trip 'til your turbo cools down enough to let you safely turn off the engine. Don’t have the time? You can solve this problem with our new T urbo imer for turbo engines By John Clarke Turbocharged engines have become very popular in recent years. Most car manufacturers have at least one turbo engine model in their range. Turbos aren’t just for performance cars or four-wheel-drives, either: many a manufacturer has found that a turbo does wonders to tiny cars with tiny engines, turning them into the socalled “pocket rockets”. One big advantage of the turbo is that it can give a considerable performance advantage over the standard unboosted types without adding too much extra complexity. Turbochargers work by directing the exhaust gas flow from the engine through a small turbine. This turbine in turn drives a compressor which boosts the atmospheric air pressure before it is applied to the inlet manifold of the engine. The resultant higher air density allows more fuel to be added prior to ignition, producing more engine power or more efficiency for the same power. Turbochargers are often mistaken for superchargers (and vice versa) because they have the same basic effect. The difference is that a supercharger 24  Silicon Chip compressor is driven by a belt directly from the engine. Turbos are usually lower in cost but can give the best of both worlds; heaps of power when you want it and fuel economy at other times. But the turbo must be allowed to cool down properly at the end of a trip before you switch the motor off. Features •  Automatic operation •  90 second timeout •  Under temperature disable •  Reset switch •  Ignition signal output for alarm •  Facility to override alarm systems which disable the ignition •  No battery power drain after timeout period What happens is that the turbine in the turbo spins very fast in the hot exhaust gases (100,000 rpm is not unusual). An immense amount of heat is involved (it’s not unusual for the inside of a turbo to glow bright cherry red!) and that heat can do a lot of damage if the turbo doesn't cool down before the oil flow to the bearings stops. Needless to say, when you turn off the engine the oil pump stops pumping and the oil stops flowing! If this happens, the oil remaining in the bearings can be cooked. It carbonises, leaving gritty coke-like residue: just what you don’t need in a high speed, high performance bearing! What you do need is a way to keep the oil flowing after you’ve stopped the vehicle – and the only simple way to do that is to keep the engine idling for a minute or so. This Turbo Timer does that job for you. You can lock up your car and walk away, safe in the knowledge that the Turbo Timer will run the engine for just long enough to safely cool down the turbo and then switch the engine off. And if you’re only nipping down to the shops for a litre of milk, the The Turbo Timer, housed in a small plastic box. Immediately below is the relay which bypasses the ignition key switch, keeping the engine running for 90 seconds after switch off. Below that again are the thermistor and reset switch. Turbo Timer won’t cut in: it will only operate after the engine has reached normal temperature. The circuitry is dead simple: a 555 timer and one or two automotive relays do the job. Automatic operation Sitting in your car for a minute or two after stopping might sound easy but it’s easy to forget; it’s also easy to think “once won’t hurt”. The S ILICON C HIP Turbo Timer won’t let you forget or miss out because if the engine is hot enough it will automatically keep running for 90 seconds or so after you switch off. You can even alight from your car and switch on the alarm during this period in readiness to leave. Of course there are going to be times that you do not want or need the Turbo Timer facility and we have catered for this. Firstly, the Turbo Timer does not operate until the engine has reached normal operating temperature. This is a fully automatic feature which requires no action on your part. It is useful if the car is just driven up the road and the engine has not had suf- ficient time to warm up. In this case the engine need not be run at idle to cool down the turbo bearings. Another scenario happens where the engine has reached normal operating temperature but has not been working hard and where the turbo has not been in operation during your drive; for example during the slow trip to work in the morning where the engine hardly revs past idle. In this case we have provided a reset feature. You simply press the reset switch immediately after switching off the ignition and the engine will stop. We have catered for alarm systems which may be triggered by the ignition being on during the time-out period. The Turbo Timer incorporates an ignition output which is disabled during the time-out period. Also, some alarms disable the engine from operating by breaking the ignition circuit at some point or by shorting the coil. In either case there is the option to add a relay which counteracts these effects during the time-out period. The disabling feature of the alarm is regained after the timeout period. The Turbo Timer electronics are housed in a small case, controlling a relay mounted outside the case. The relay contacts connect across the ignition switch to maintain ignition power during the time-out period. The relay is a heavy duty type specifically for automotive use: the contacts can handle up to 25A. Circuit The circuit for the Turbo Timer uses a single 555 timer, IC1, a transistor or two and a sprinkling of other components. The circuit is powered from the switched side of the ignition switch via diode D1 and a 33Ω resistor, giving an 11.4V supply rail from a nominal 12V car battery. The 16V zener protects against voltage surges while the 100µF capacitor smooths the supply and also maintains it for a short time when the ignition switch is turned off. This is important for correct circuit operation. When IC1 is powered via the ignition and assuming the thermostat switch TH1 is open (pin 4 at 11.4V), the output at pin 3 is low and both transistors Q1 and Q2 are off. The November 1998  25 Fig. 1: the circuit of the Turbo Timer is based on a 555 timer IC. It is shown with the optional components (RLY2, D4, Q2 and the 2.2kΩ resistor) if an alarm bypass circuit is required. 220µF capacitor at pin 6 is held discharged via the 1kΩ resistor and the low state of pin 7. The trigger input (pin 2) is held high via the 100kΩ pullup resistor while the negative side of the 2.2µF capacitor is also pulled high via the normally closed contacts of RLY1 and the 1.8kΩ resistor. When the ignition switch is opened (ie, the ignition key turned off), the negative side of the 2.2µF capacitor is pulled low via the 10kΩ resistor. The positive side of the capacitor follows this voltage down, triggering IC1 via pin 2. This releases the low on pin 7 to allow the 220µF capacitor at pin 6 to charge via the 390kΩ resistor. The now high pin 3 drives the base of Q1 and Q2 via 2.2kΩ resistors. Transistor Q1 drives relay RLY1's coil and Q2 drives the optional RLY2, if fitted. RLY1's common and normally open contacts close, shorting the ignition switch. The normally closed contact is open and held low via the 10kΩ pull-down resistor. This contact can be used for an alarm system ignition input since it is low during this timeout period but follows the ignition supply at other times. The 2.2µF capacitor at pin 2 now begins to charge up to the full supply voltage via the 100kΩ resistor and the 10kΩ resistor to ground. 26  Silicon Chip Diode D2 protects the 555 timer by preventing the voltage at pin 2 from being elevated to unsafe levels, as could happen if the 2.2µF capacitor was fully charged and the relay contacts opened. This would lift the negative side of the 2.2µF capacitor to +10.2V, pushing the positive side to more than 21V, in all likelihood blowing the IC input. D2 also protects the IC from overvoltage caused by any spikes from the ignition system when the RLY1 normally closed and common contacts are connected. The output at pin 3 1/remains high and the relay is held on via Q1 until the 220µF capacitor at pin 6 charges up to 2/3 of the supply. When this threshold is reached, pin 3 goes low, switching off transistor Q1 (and Q2 if fitted). The relay contacts of RLY1 revert to their normal position, cutting off the supply to the ignition circuit, stopping the engine. At the same time, the 220µF capacitor is discharged via the 1kΩ resistor at pin 7. If the reset switch S1 is pressed during the charging period, the 220µF capacitor charges immediately via the 1kΩ resistor and the timing period ceases. You may be concerned about any delay between turning the ignition key off and the relay contacts pulling in. Of course there is a small lag but in practice it doesn't matter – it's much quicker than turning your ignition key off and on again very quickly. The engine doesn't have time to stop. Temperature detection The thermostat (TH1) at pin 4 disables operation of the timer whenever it is closed. It is installed on the radiator of the vehicle so that it can monitor the engine temperature. When the radiator is cold, the thermostat contacts are closed and they hold the reset pin low. This stops pin 3 going high so the timeout does not operate. When the radiator temperature reaches about 80°C, the thermostat opens and so pin 4 is pulled to 2.4V via the 10kΩ and 2.7kΩ voltage divider between the supply rail and ground. The circuit can now operate normally when triggered, with pin 3 going high for 90 seconds. The 100µF capacitor at pin 4 is included to prevent IC1 from being triggered when the ignition is switched on and TH1 is open. The 2.7kΩ resistor ensures that the 100µF capacitor is fully discharged. Relay 2 Relay 2 is included to enable the Turbo Timer to operate even if you have an alarm system which disables the ignition system. The relay contacts are changeover types so that you can make the required connection if the alarm system breaks the circuit or break the connection if the alarm applies a short to part of the ignition. This relay (along with Q2 and its 2.2kΩ base resistor) is optional and need not be used even if you have an alarm of this type. It means, though, that the alarm cannot be set until after the turbo timeout period. Standing around waiting for the turbo timer to time out is about as convenient as sitting around waiting for a minute or so to turn the engine off – hence its inclusion for those vehicles fitted with ignition-disabling alarms! Construction Most parts for the Turbo Timer are mounted on a PC board coded 05411981 and measuring 104 x 58mm. The PC board can be housed in a suitable case measuring 130 x 68 x 41mm. Alternatively, you can house the entire circuit in heatshrink tubing. The photographs show a plastic case but there are some security arguments for a metal (diecast) case; more on this subject shortly. The PC board was sized to clip into the plastic catches on the side of the box. Make sure that it is of the correct width to fit snugly in position. Use a file to narrow down the PC board if it is too wide. Begin construction by checking the PC board for shorts between tracks and possible breaks, then insert and solder in all the PC stakes. The resistors can be installed next using the accompanying colour code table as a guide to selecting each value. Alternatively, you can use a digital multimeter to measure each value. If in any doubt as to a resistor’s value, check it anyway. Diodes can be mounted next, taking care with the polarity of each. Make sure that you use a 1N914 or 1N4148 type in the D2 position. ZD1 must be a zener diode; it may be marked 1N4745. Take care of any polarity-conscious components: transistors Q1 & Q2 (which are positioned as shown with the curved side toward the edge of the PC board); IC1; the diodes (don’t mix up the zener with the others) and the electroyltic capacitors Fig. 2: all components except the reset switch, thermistor and relay(s) mount on a small PC board. Take care with D2 and ZD1 – they sometimes look almost identical. Fig. 3: this full-size PC board pattern can be used to etch your own board or used as a reference when checking a commercial or kit board. We mounted our relay on the end of the case, but there is no necessity for it to be so mounted. If you mount yours on the end of the case, drill the case to accept the mounting bolt for the relay and about a 10mm hole for the wiring loom to exit. Wiring We used light duty wire for all wiring except for the wires to the ignition switch and wires connecting to termi- nals 87 and 30 of the relay. These must be wired with heavy duty automotive wiring. Use insulated crimp female spade connectors to connect to the relay terminals. You can test the Turbo Timer using a 12V supply with a rating of at least 200mA. First connect the positive supply to “+12V from battery” and the negative to the “chassis earth” terminals on the PC board. Do not connect the TH1 thermostat at this stage but November 1998  27 Parts List 1 PC board, code 05411981, 104 x 58mm 1 case, 130 x 68 x 41mm 1 20A 12V horn relay with change over contacts (RLY1) 1 80°C thermostat with normally closed contacts 1 normally open pushbutton switch (S1) 7 insulated 6mm female spade connectors 2 crimp eyelets 8 PC stakes Use this photograph in conjunction with the PC board overlay when assembling your Turbo Timer. you can connect the reset switch to its terminals. Now short the “+12V from battery” and “+12V from ignition switch” PC stakes. Nothing should happen but when you disconnect this wire (which simulates the opening of the ignition switch) , the relay should be activated. The relay should be de-energised after about 90 seconds. Try the operation again and check that the relay drops out when the reset switch is pressed. Temporarily short the thermistor terminal to the chassis earth terminal and ensure that the relay does not operate. This simulates operation on a cold engine. If the circuit operates properly you are now ready to install the Turbo Timer into your vehicle. Security One important consideration for a Turbo Timer is vehicle security – not, as you might imagine, the problem of the vehicle being driven away during the timeout period. You are usually close enough to the vehicle during that period for it not to be a problem. Vehicle manufacturers these days go to considerable lengths to hide, or camouflage, ignition wiring to make it just that much harder for thieves. You will have to identify which wires are which to install the Turbo Timer – and it will probably take some time (a commodity most thieves don’t have). Having connected the Turbo Timer successfully, you will have bypassed a lot of that security and identified the two most sought-after connections (for a thief) – the ignition terminals. For this reason, your installation needs to be carefully thought out. It is almost certainly best NOT to install the Turbo Timer under the dashboard where it can be easily got at or where a thief can spend time without drawing too much attention. The best spot is probably inside the engine bay, hidden if at all possible. If you can make it look like part of the wiring loom (eg, with heatshrink tubing) so much the better. If you mount the Turbo Timer in a case, remember that underneath the bonnet of a turbocharged vehicle is a very hot, hostile environment. Ensure Semiconductors 1 555 timer (IC1) 2 BC337 NPN transistors (Q1,Q2)* 3 IN4004 1A diodes (D1,D3,D4) 1 1N914, 1N4148 diode (D2) 1 16V 1W zener diode (ZD1) Capacitors 1 220µF 16VW PC electrolytic 2 100µF 16VW PC electrolytic 1 2.2µF 16VW PC electrolytic 2 0.1µF MKT polyester Resistors (0.25W, 1%) 1 390kΩ   1 2.7kΩ 2 1kΩ 1 100kΩ   2 2.2kΩ∗ 1 33Ω 2 10kΩ   1 1.8kΩ Option 1 20A 12V horn relay with change-over contacts (RLY2) Miscellaneous Automotive connectors, Automotive wire, solder, etc. * Q2 and one 2.2k resistor are also optional if RLY2 is not fitted that the case is mounted well away from the “hot” side of the engine and that a suitable case is used to prevent water ingress. In fact, we would prefer to see a metal diecast case used. Sure, Resistor Colour Codes         No. 1 1 2 1 2 1 2 1 28  Silicon Chip Value 390kΩ 100kΩ 10kΩ 2.7kΩ 2.2kΩ 1.8kΩ 1kΩ 33Ω 4-Band Code (1%) orange white yellow brown brown black yellow brown brown black orange brown red violet red brown red red red brown brown grey red brown brown black red brown orange orange black brown 5-Band Code (1%) orange white black orange brown brown black black orange brown brown black black red brown red violet black brown brown red red black brown brown brown grey black brown brown brown black black brown brown orange orange black gold brown radiator hose using tie wire, cable ties or similar. One contact for the thermal switch connects to the Turbo Timer PC board while the second terminal connects to chassis near the radiator using a self-tapping screw to secure the eyelet. Incidentally, if you ever need to disable the Turbo Timer (eg, for vehicle service), shorting the two thermistor terminals together is the easiest way to do it. You may wish to connect up the optional second relay (along with Q2 and its 2.2kΩ base resistor) if you have an alarm system installed. Fig. 4: full-size artwork for the label on the plastic box used for the prototype. This Note that you should use the igmay need slight enlargement or reduction (eg by a photocopier) on a metal box. nition output on the Turbo Timer they cost a few bob more – but what’s connectors. if the alarm monitors the ignition. your car worth? You will also need a chassis point Details of how to wire up the second to connect the ground supply of the relay are shown in Fig.5. There are two Installation circuit to the battery negative termi- alternatives catered for in this wiring. nal. This can be an existing screw in Taking into account the above Firstly in Fig.5a, the wiring diagram comments, find a suitable position for the metalwork or a separate self-tap- shows how to wire the relay to counping screw which secures the eyelet mounting the unit. teract the alarm unit from shorting out Locate the fused side of the ignition terminal for the ground lead in place. the ignition. If mounting the relay externally you circuit and the fused side of the battery Fig.5b shows how to counteract supply – you may need a workshop will also need to find a suitable screw the alarm unit when it open circuits manual to help you with this because – the mounting plate usually needs to the ignition system. The normal be grounded. it is not normally something you’ll alarm ignition disable feature will be If you are the only driver of the maintained once the turbo timeout find in an owner’s manual. In most vehicles, the fusebox is vehicle, it is better to mount the reset period has expired. Use heavy duty switch in a not-too-obvious position. automotive wire for the connections. mounted under the dash. It's easy to check which connectors are fused If you have a dashboard with any spare If the 90 second delay is too short using either a 12V test lamp or a mul- switch mounting plates, you could or too long, you can adjust it by vartimeter – pull out the fuse and see if use one of these. If others drive your ying the 390kΩ resistor between the vehicle, or if putting it in for service, positive supply and pin 6. Increasing you still have voltage! The ignition circuit is usually most let them know it has a Turbo Timer the resistor will increase the time, defitted and where the reset switch is! easily accessed under the bonnet creasing it will (surprise!) decrease the The thermal cutout switch can be timeout period. The 220uF capacitor rather than under the dash. Most vehicles have the ignition fuse separately mounted on the radiator body but could also be increased to 470uF for not on the cooling core. You may be a longer period. mounted under the bonnet. The wiring to all points should be able to secure it using some steel wire Using It made using good quality automotive which wraps around one of the side chambers by passing it through Operation is virtually foolproof: the cooling fins. Make sure that when you park the vehicle, ensure the surfaces of both thermal it is in "park" (auto transmission) switch and radiator are mating or "neutral" (manual transmission), squarely. engage the handbrake fully, turn the A smear of heatsink com- ignition key off, remove it, get out pound between mating surfac- and lock up. es will ensure better thermal Note the comments above about Fig. 5: if your alarm system disables the contact. setting your alarm, if you have one. ignition by shorting it out, use option (a). As an alternative, on a copFinally, a warning: if leaving the car If it open circuits the ignition system, use (b). per or brass radiator you could in an enclosed area (such as a home solder a couple of M3 nuts to garage) beware of the carbon monoxide the radiator body and secure fumes which will be given off during the thermal switch to these the engine run-on period. Park the using the integral mounting vehicle so that its exhaust is directed plate. outside or leave the garage door open. Otherwise, you may need to Carbon monoxide is colourless, odourattach the thermal cutout to the SC less . . . and poisonous. November 1998  29 SERVICEMAN'S LOG Big tellys, PCs & car computers Why is it that all large-screen TV sets are located up flights of stairs, making it impractical to move them? I recently came across two such monsters, along with a PC that kept losing its icons. I also got tangled up with a couple of car computers. It was with fear and anticipation that I set off to “look at” a large screen Sanyo TV, as Mrs Collins had begged me to. She was unable to tell me the model number as she could not get to the back of the set but she repeated that the fault was no pic­ture. And because she was recuperating from an operation on her leg, she really needed to watch the telly. When I arrived at the third storey unit, mentally noting that there was no elevator, I was surprised to find that her home was even smaller than I had imagined it to be. You couldn’t miss 30  Silicon Chip the 78cm stereo TV as it took pride of place in the living room. The furniture was spread out in a semicircle around the set, as though it was praying to the craven idol. How they got the set into this matchbox must be a story in itself but one thing was for sure – it was going to have to be fixed on location, as I certainly didn’t have the facilities to take it to the workshop. When I finally managed to move the set out a fraction from the wall and crawl behind it, I established that it was a Sanyo CPP3310TX-01 (A4-A33 chassis). Because of the restricted space, it took some effort to remove the back but this did little to make the access any easier. Secretly, I prayed to the Patron Saint of Television for a merciful and quick conclusion to this repair. I had already established that there was sound but no raster from any source – be it from the TV tuner or the AV inputs. Nor was there any Teletext on Channel 7. I propped up a large mirror in front of the TV so that I could monitor any activity from the rear and then turned up the screen control on the flyback transformer to produce a blank clear raster. Well, the report card on the TV now showed me that almost all the circuits were working. However, the luminance and chromi­nance signals were disappearing somewhere between the video detector and the picture tube. And because there was no picture from the AV inputs, this meant that the problem could be shifted a little further away from the detector – possibly to the analog switching circuitry. Even so, it was looking more and more like a problem with the small-signal decoding stages and for this I needed a circuit diagram. Mercifully, Mrs Collins had kept the one that came with the set and so I started by checking the nine major voltage supply rails (B1-B9) from the switchmode power supply, the flyback transformer and the remote control receiver auxiliary sup­ply. I also checked the ancillary rails which are derived via IC regulators and checked the low voltage rails to the signal pro­cessing circuits but nothing was amiss. By now, I was suspecting IC201 (M513086P) – the jungle IC – but I really couldn’t go any further without an oscilloscope. I left, having made an appointment to call back later in the week. As I drove off to the next job, one point I had noticed with the TV was niggling away at me – there was no on-screen display. I had dismissed this at the time but now I couldn’t help feeling that I had been down this path before. When I got back to the workshop, I phoned Sanyo Technical Support and they also (without prompting) suggested the jungle IC. They also advised me to check crystals X421 and X261. To save time, I ordered the IC just in case this was the problem. I was back at Mrs Collin’s little flat a few days later and this time there was even less room as I had brought an oscillo­scope and a signal generator. Access to the underside of the main PC board was impossible and it wasn’t much better for the top because the AV board got in the way. Because nothing could be seen on the screen, I couldn’t tune the TV into the RF output of the pattern generator so I injected colour bars into the video input phono socket (AV1) instead. It took me quite some time with the circuit to finally work out that the AV module not only selects the various sources but also splits up the video into chrominance and luminance signals. The latter then goes through a “video unit” which is a noise reducer circuit, before finally arriving at pin 18 of IC201. The CRO confirmed this and also that the crystals were oscillating with the remote control. Next, I selected a channel number which had good sound before checking the video output from the IF pack on test point TP-J with the oscilloscope. The signal was there and also at IC201. Reselecting AV1, I then measured the colour difference output signals from IC201 on pins 1, 2 and 3 and was surprised to find them all there. I then followed these signals through the AV board “Super Imposer” (IC1307), which switches through the Tele­text, and onto the CRT socket where the signal died after the emitter input to the output transistors. It was then that the bells began ringing, because I had been here before with a very similar problem in a Palsonic 5138 TV set (see November 1997). Sure enough, here was the exact same component, namely a 120kΩ resistor (R692) feeding the base cir­cuit of the video output transistors from the +200V rail. And once again, the high voltage had been too much for this low-wattage resistor and it had failed, switch­ing off all three transistors. If only I could remember all these faults, although I’m sure I won’t for- Fig.1: the standby switching circuitry in the Sony KV-C2931S. A break in the circuit between R634 and D624 meant that Q601 was being turned off but the fault was intermittent. get this one the third time around. Anyway, Mrs Collins was delighted and I was left with the challenge of disengaging myself from the tangle of equipment and getting out of that tiny flat in one piece. Another monster In the meantime, yet another house call was booked in for a large screen TV. Why is it that all the biggest sets are located in the most difficult positions – usually up flights of stairs with no lifts? Or is it just me being paranoid? This time, the set was a 1990 Sony KV-C2931S, using an AE-1B chassis made in West Germany. The complaint was intermittent no sound or picture. Mr and Mrs Mowbray, who owned the set, were a retired couple living on the top floor of a duplex and had enough trouble getting up and down the stairs as it was, so they were in no position to assist me with the TV. Once again, it was a case of the workshop going to the TV rather than vice versa. Because I had serviced so many of these sets, I thought that the fault would be easy to fix. It would probably turn out to be a dry joint on the motherboard and I was quite confident of an early and successful victory as I climbed the many stairs. I arranged with the Mowbrays to get a blanket and cushions ready and then gently tilted the set over onto its front to rest on them (the cushions, not the Mowbrays). Removing two screws and a couple of clips gave me access to the underside of the set and I then spent over half an hour re­soldering many suspect joints on the motherboard, especially around resistors R614 and R653 and around Q608. Some of the dry joints were inaccessible under the black plastic frame and the only cheap and quick way to address these is to cut a small part of it away. Anyway, I resoldered all the transformers, transistors, diodes, plugs and sockets and some of the power ICs. Finally, satisfied with a job well done, I reas­sembled it all and made sure all was working well before confi­dently leaving. Unfortunately, my triumph was short-lived – Mr Mowbray phoned about two weeks later and said it was doing the same thing again and could I please call back. Disappointedly, I returned, and sure enough the picture and sound would come and go as you tapped the set. Now I had in fact tested this thoroughly the last time, when tapping it or even thumping it made no difference. This time I left the set in an upright position and gently removed the back, then tapped around the set exploring for more sensitive spots. After a while, I felt sure that the problem lay on tuner IF module A, so I reworked the soldering all over this board, concentrating on the edge connectors, the tuner and any coils. I then unsoldered the IF module (VIF901) and reworked November 1998  31 the soldering inside there, especially over any coils and ceramic filters which, I might add, were almost all dry-jointed. Once again, full of confidence, I reassembled everything and tried tapping around the whole set, especially the tuner IF module. The picture and sound were rock steady and I left feeling somewhat annoyed that having soldered so many bad joints the first time, I had discovered even more the second time. But wait, there’s more. This is where the story should have ended but unfortunately it didn’t. About four weeks later, a rather tetchy Mr Mowbray called again and told me the set still wasn’t fixed. For a while they could tap it and the picture and sound would return but now it was gone completely. The only thing showing any sign of life was the green on-screen display. I returned as soon as possible to the Mowbrays, armed with the full kit again – namely the oscilloscope and pattern genera­tor, which I connected to the AV1 input SCART socket via an adap­tor. I then began tracing the video signal from the SCART socket (pin 20) to the output from the AV board (pin 16, J1-41) and onto the mother­board. From there, I traced the signal from the chroma decoder and finally to the Teletext board (CNV-01 pin 3). But there was no video going into video 32  Silicon Chip amplifier stage Q598 (wave­form 22) which supplies the sync separator (IC501). It was this puzzling part of the problem that wasted half an hour of my time. The circuit clearly shows a direct path from pin 3 to C592 and then onto the emitter of Q598 but in reality, there was a link. This is designated JW105 but had not been installed in this set. Shorting across the link position restored both picture and sound, so you may be forgiven for thinking that just refitting the link would be the answer. However, it does not explain why simply tapping the set used to fix the problem. The answer was that Teletext is an optional accessory and the link is only fitted when this option is left out. If Teletext is included, as it was in this case, the video goes into the Teletext unit on pin 3 and comes back out again on pin 2. This meant that the problem was now narrowed down to the Teletext module, or so I thought. Removing the V board and examining it revealed yet more dry joints, especially around Q01, the 5V regulator stage. Unfortunately, re-soldering the joints didn’t fix the problem – there was still no 5V rail. I soon discovered that not only did I not have 5V but that the 7V rail into the module was also missing. The 7V rail comes in on pin 6 of connector CNV-01 and I traced the line back to the collector of transistor Q601 (the standby switch) on the mother­board. There was 8.4V on its emitter (which is correct) but this same voltage was also present on the base, thus completely switching the PNP transistor off. Q601’s base is controlled by transistors Q606 and Q609 via R634, D624 and R618 – see Fig.1. There should have been 0V on Q609’s collector and this proved to be the case. There was also 0V present on the cathode of D624 but R634, which is connected directly to it, measured 8.4V. This meant that there had to be a break in the board track between D624 and R634, although the track looked perfectly OK. This track, by the way, is only about 25mm long and passes next to a hole drilled through the board. This might have been a screw hole but there was no screw fitted – maybe it was only used in the course of manufacture and discarded later. I scratched away the lacquer covering the track and, using an ohmmeter, eventually found a hairline fracture in the copper. Resoldering the crack fixed the problem and I carefully reassem­bled the set. A check some three months later revealed that everything was still OK, so I think I’ve finally fixed the mon­ster. If I’m wrong, I’m returning with my best fine-tuning tool – my baseball bat. John Cleese will have nothing on me after I’ve given that set a stern talking to. Missing icons In addition to the usual VCRs and TV sets that come my way, I’m also often confronted with computer problems. Some of these can be quite unusual and I have one such story this month. The first was a 1994 ICL ErgoLite computer, which is actu­ally an Acer 80486 DX-50 in disguise. Its main problem was that it was unable to save any setting made within Windows 3.11 on exit, resulting in a blank Program Manager with no icons. At first, I thought that this would be a case of simply reloading Windows over the top of the existing installation but this didn’t help. I then spent some time reloading DOS 6.22 and customising its config.sys and auto­exec. bat files to optimise memory but that didn’t help either. I then ran Scandisk, a virus checker and defragg­ ed the drive but I wasn’t getting anywhere. The resources were fine and the computer hardware was fine too. My next step was to examine sys­ tem.ini and win.ini but again I could find nothing untoward. What finally put me onto the right track was thinking more carefully about what was actually happening and especially why the icons were disappearing (very Agatha Christie). This part of the operating system is controlled by Progman.exe and customised with Progman.ini. Using my trusty XTree Gold (the one and only), I examined Progman.ini and com­pared it with the Progman.ini from another computer that worked. Normally, this text file has two headings, [Settings] and [Groups], the former giving details as to how the groups are arranged and the latter describing what the groups actually are. However, on the faulty computer there were two or three lines of machine code and then the settings and codes were repeated about half a dozen times, often with conflicting information. At last I was getting somewhere. Hopefully, all I would have to do is edit the Progman.ini file but first I went to the Windows directory and printed out a list of all the group files (*.grp) for use as a reference. After that, I backed up Progman.ini and then edited the file by removing all the machine code and then listing all the Group files under the [Group] heading. Finally, I edited the lines under the [Setting] heading, removing any duplicates in the process, and resaved the file. This simple measure completely fixed the problem. The next time I went back into Windows, all the icons were there – indeed there were even some duplicates. A little extra housework made everything shipshape and the program groups now remained in place each time I exited and rebooted Windows. My guess is that the problem had been caused by the comput­er being turned off (or crashing) while Windows was still run­ ning. This had created lost clusters and chains which had been repaired as best as possible by Scandisk. Unfortunately, the Progman.ini file had been corrupted and could only be manually repaired using the method just described. The moral of the story is to always exit Windows properly before turning the computer off. Car computers My final two stories for this month are also about comput­ ers but this time, they involve car computers. So how did I come to get involved in car computers? Simple – a mate of mine runs an automotive workshop. The first story is about a Eunos that wouldn’t start, although we were pretty sure that it wasn’t the computer itself that was at fault because a substi­ tute didn’t fix the problem. The car would crank and there was spark but no injector pulses. Based on this, we deduced that the problem probably lay somewhere between the computer and the fuel injectors but there were a few other possibilities. With amazing luck, we actually managed to obtain a photocopy of the wiring diagram for the car but not of the computer itself, unfortunate­ly. We began by using a multimeter to establish that 12V was getting to the computer and to the injectors – and this proved to be the case. However, it was prophetically pointed out at the time that it isn’t a good idea to use a multimeter in auto elec­trics, as the internal resistance is so high that it can give very misleading results. Instead, it is far better to use a 12V lamp probe but we couldn’t find the workshop unit at first. After these initial checks, I decided to use a CRO to check the input pulses from the two crank sensors (why two?) and the output pulses from the computer to the fuel injectors – this while someone else cranked the engine. Everything seemed to be working perfectly and so it definitely looked like a wiring loom problem. Next, I moved the CRO to the engine bay and checked the pulses going directly to the injector connectors. These were all present, so why wasn’t it working? It was at this point that the lamp probe was found and we checked the 12V rail to the injectors again. And whereas the meter had told us there was a full 12V, the lamp told us differ­ ently. The 125mA globe (24V 3W) hardly lit, which indicated a high resistance in the wiring loom and/or the relays between this point and the battery. Even though we had the wiring diagram, we still had diffi­culty following the leads and identifying the various plugs and sockets. To begin with, in order to confirm our diagnosis, we connected a jumper from the fusebox to the injectors and cranked the engine. To our delight, it immediately fired up but the engine stopped as soon as we removed the jumper It was while we were tracing the 12V rail with the lamp probe that we almost had a disaster. The lamp probe consists of a festoon globe inside a hollow uninsulated metal cylinder with a sharp point on one end. The other end has a lead with a crocodile clip going through an insulator, a spring and another insulator to the other end of the globe. Unfortunately, I pulled too hard on the lead while trying to reach one of the sockets and broke the internal insulator, thereby shorting the lamp completely out. Immediately, buckets of amps start­ ed flowing and the lead started to melt. Fortunately, I was able to break the circuit within a second or two of seeing the smoke – but what damage had November 1998  33 Serviceman’s Log – continued I caused? Well, as it happened, none because when we cranked the engine, it started immediately. The high current had “cleaned out the cobwebs” and improved the bad connection we were trying so hard to find. This was maddening because this was now a classic Clayton’s fix – ie, the repair you have when you are not having a repair! Luckily for us, we had already narrowed it down to a plug and socket near the fusebox marked X07 (white and red wire) and actually wiggling it with a x1 ohmmeter across it saw the needle tremble slightly. So rather than leave it with a “she’ll be right, mate” attitude, we soldered a jumper lead across the plug and socket. The car was then soak tested(!) but it gave us no more grief. Airing a Subaru The final story in this computer trilogy of bravely going where no-one else will go concerned a 1990 Subaru, which had an electronically-controlled suspension height system. This consist­ed of four air-bags in lieu of coil springs that were individually pump­ed up and down with a compressor and controlled by solenoids. These were in turn controlled by a 34  Silicon Chip microprocessor, either au­tomatically or when commanded by the driver. Of course, the problem was that nothing was happening when the buttons were pushed – the suspension remained in its lowered position. Various other people had had a go at trying to fix the problem and the bone was being pointed at the computer as the likely source. Once again, we had a wiring diagram for the vehicle, which was a relief, but not for the computer. Initially, I was given the computer box only and told “go fix”. I must confess that I wasn’t all that optimistic at first but what did we have to lose? The computer consisted of a large microprocessor chip and a lot of peripherals, plus seven 2SD1392 transistors whose collec­ tors went directly to the connection sockets. Initially, I spent some time checking for all the obvious things (ie, dry solder joints, dry electros and short/open circuits) before turning my attention to the transistors. These all measured good except for one which was badly cooked. You beauty! I reported back that I had found a fault in the unit but pointed out that some external fault must have caused the damage. There was nothing for it but to check it out in circuit with a lamp probe. First, we established that there was 12V going into the computer on pins 2 & 3 and that there was also 12V on the collec­tors of all the transistors. We then identified which transistor did what. Four controlled the airbags at each wheel, one the compressor relay and the other two the charge and discharge valves. Our next step was to short each of the collector connec­tions on the socket to ground in turn (with the computer un­plugged). Each solenoid operated correctly except for the dis­ charge valve which is controlled via pin 1. And guess which transis­ tor controlled pin 1. Temporarily, we took the discharge valve out of circuit and refitted the computer. This confirmed that it was actually doing its job because we could hear the relays working. So why wasn’t the suspension being raised and lowered? The answer was that the discharge valve was not only short circuit but was also stuck open. Unfortunately, it is mounted on the compressor and this can only be accessed by removing lots of other parts and putting the car up on the hoist (the compressor and valves sit just above and in front of the passenger’s front wheel). At first we thought that we would be scuppered by the hoist because the wheels would drop and the computer would think that the system was fully discharged so we couldn’t test it. However, we managed to confirm that the air-switch solenoids were operat­ing but that there was no air to pump the airbags. We checked the reservoir and pipes for leaks but found none, which meant the problem was definitely the discharge valve. Unfortunately, this is an integral part of the compressor assembly and is a totally unserviceable unit. It wasn’t easy removing and replacing the compressor but a new one at – wait for it, almost $2000 – finally fixed it. After all that, give me a telly SC any time. NOTE: please quote part numbers in brackets when ordering if available. LEDs, FLASHING LEDs & PHOTO TRANSISTORS (NOTE: When buying LEDs that most STANDARD LEDs are only 1mC or less!!) 3mm 3000 mC - YELLOW..... 10 for $5 300 mC - GREEN..... 10 for $3 1400 mC - RED..... 10 for $6 Photo Transistor..... 10 for $5 5mm 3000 mC - YELLOW..... 10 for $6 300 mC - GREEN..... 10 for $4 3500 mC - RED..... 10 for $6 Photo Transistor..... 10 for $5 5mm FLASHING 3000 mC - YELLOW..... 10 for $10 60 mC - GREEN..... 10 for $10 300 mC - RED..... 10 for $10 10mm 3000 mC - RED..... 10 for $12 10mm FLASHING 400 mC - GREEN..... 10 for $12 3000 mC - YELLOW..... 10 for $12 5mm INFRA-RED 850nM 10 x the brightness of 880nM but have some visible red $1.30 Ea. 10 for $10 ***** MYSTERY BAG OF 100 LEDs ***** Contains: No standard LEDs!!! All premium quality. or better with at least (if not more) 1blue, 1 ultra green and 1 flashing. An absolute steel at $8 per bag. FOG MACHINES Professional quality fog machines. This unit would be the perfect partner to our laser light shows, ideal for discos, parties fashion parades etc. A special intro. price of under $200 Coming soon Reserve one now (G51) *** SPECIAL BARGAIN *** 12V/7Ah GEL BATTERY BARGAIN Fresh stock of NEW standard gel cell battery plus a free trickle charger for just $30 PRE-BUILT MINI AMP FOR CAMERAS 20X21mm. Includes microphone, cable & connector, requires 12VDC $10 FREE VHF VIDEO MINI MODULATOR With every camera.(Rm2). This unit allows you to use your Tv’s antenna input & if you need sound just add $4 to the price of a camera for our VHF modulator sound kit POWERFUL 80 IR ILLUMINATOR With strong universal swivel mount & 50X50X50mm housing:$36 For other sizes check our Web Site NEW STEPPER MOTORS 30 oz./in. torque, 2.5 deg. 144 step, low voltage, compact 57 x 38mm: $14 ********************************************** TWO STEPPER MOTOR DRIVER DRIVER KITS WITH MOTORS ********************************************** ***STEPPER MOTOR DRIVER KIT #1*** COMPUTER CONTROLLED STEPPER MOTOR KIT: can drive larger motors, has optoisolation. Inc. software and notes: $40 or $50 with two used 23 frame 200 step 1.8 deg. motors!! KITS OF THE MONTH PIC MICRO PROGRAMER JUST $25 Design your own microprocessor controlled devices or even products and maybe make your fortune! Learn program your own 16F83 /16F84 /16C84 micro- controllers with this kit the simple way. with this small, cheap but powerful chips Kit inc. program examples and notes PCBs, all on-board components, Db25 connector and a PIC chip ready to program. An incredible bargain at just $27 Software available free to download from our web page $27 12VDC - 240AC INVERTER Features include modified square wave output, Auto start with load sensing, Uses six power MOSFETS with minimal heatsinking required. 200 - 600VA. dependant on trans former size. To save money you can use an rewind your own transformer. Basic kit includes pcb & all on-board components + 4 X 60A MOSFETS. $35 Requires 240V to 8-0-8 V transformer.. Ring or E-Mail for more details. $35 WE ARE LOOKING TO BUY NEW & USED SURPLUS OR OBSOLETE STOCK COMPONENTS, MODULES, PCBs, MECHANISMS, MOTORS, GEAR BOXES, HOUSINGS, CABLES, CONNECTORS, SWITCHES, METERS, COMPLETE ASSEMBLIES JUST CALL OR FAX WITH THE DETAILS. WHAT MIGHT APPEAR TO BE WORTHLESS TO YOU MAY BE VALUABLE TO US. LARGE OR SMALL QUANTITIES YOU MAY BE SURPRISED WHAT YOUR STOCK IS WORTH!!! NEW!!! CODE HOPPING LASER DIODE POINTER KIT Did you ever imagine you UHF MINI TRANSMITTER / could buy a very brightl RECEIVER PAIR laser for just $15? High security in a very small well guess again!!! (K35) transmitter and receiver (keyNEW 1/2/3 AXIS CNC SYSTEM. fob size) pre-built package. Both (computer numerical control) This system crystal locked on 433Mhz, with includes a new stepper motor driver kit approx.100m range. The (one kit required for each axis) designed to receiver will drive central locking be used with software freely available on systems, indicator relays, boot the Internet for use with home or release relays, flashing lights professionally built a milling machine, and more:$100 for 1 TX & 1RX. lathe, engraver or cutter etc. with home & extra Txs: $30. 12V- 12A limit switches and a high degree of relays:$2.50Ea. accuracy (can be better than .001”. We supply the kit inc. Pcb all on-board KEY-CHAIN LASER POINTER components etc. plus Internet resources Very bright 650nM laser pointer shareware software & building or buying in a high quality machined mechanical components. Around $30 per metal housing axis. Call for further details. UNIDIRECTIONAL ELECTRET FOR SALE TO ADULTS ONLY MICROPHONE VERY BRIGHT LASER MODULE New quality product 650 laser module as with clip, 3M lead, used in the 2.5mm plug: $4 Make above pointer. a stage quality wireless (Lm2) microphone by combining it with our FMTX MK2 trans-mitter kit: $16 FOR SALE TO ADULTS ONLY for the kit plus the microphone ************* SOLDER MOP ************** *** NEW *** NEW *** NEW *** Quality SERVISOL SOLDER MOP (UK) HIGH POWER IR TRANSMITTER AND brandThis stuff really sucks!!! RECEIVER Applications include data Yes it sucks up transmitter, powerful Passive infrared de- solder better tector, IR invisible fence / gate & doorway than a solder monitor. Range: with 5 IR LEDs (can drive sucker up to 50 LEDs) passive mode 10m (5 At $2.50 per 1.5Mtr. roll or 3 rolls for $5 LEDs), active mode 40m (5 LEDs). Range CGA COLOUR MONITOR.... NEW 12V can be boosted with a cheap torch re- DC-1A 6" colour monitor, flector. The kit has active high & active low ready to be enclosed, outputs for relays etc Simple to construct no housing , just the tube, PCB can be cut into two for active mode or driver PCB's and data for data transmission. Kit inc. PCB, all on- sheet. board components, 5 IR LEDs + salvaged now just $40 (G62) new plastic case All for $28 **************NIGHT VISION*************** 2 AXIS ROBOTIC ARM WITH GRIPPER Back in stock. We have a REF. SC Dec.97. This robot uses the well limited quantity of deep known Mini serial servo controller to Infra-red night vision control up to 8 servos from your tubes + lenses & suppcomputer’s serial port using Qbasic that lies to suit. “RING US” 20-30 SECOND DIGITAL SOUND comes free with DOS. RECORDER KIT. This could be used as an Plans + software $8 answering machine at your front door or as Mini SSC $55 a personal reminder device. Good quality Servos $15 Ea. sound Uses LSI chip with memory etc. STEPPER MOTOR AUSBOT uses built in. Kit includes DRIVER #2 KIT Inc. a large 3 servos PCB all on-board used 1.8 deg. (200 step / components, rev23 frame ) motor & uses microphone, SAA-1042A IC. Controls. switches & speaker.$14 (K124) inc. ext. clock, on-board clock CW or CCW rotation, ************ OPTICAL PRISMS *********** Series I 3 - 4 CHANNEL UHF RECEIVER: half / full step, enable/disable,with one : These are military spec. Ref: EA Mar 94. Control up to 4 output $20 / 2 motors:$30 optically pure glass prisms relays. Uses a pre-built and pre-aligned set in a diecast mount UHF (304MHz) receiver module & security (removable).They are in coding ICs. Output relays have 5A contact A1 condition and stored in PO Box 89 Oatley NSW 2223 ratings and can be configured for toggling plastic (no scratches) Ph ( 02 ) 9584 3563 Fax 9584 3561 They operation at each press of a Tx button or will show colours orders by e-mail: oatley<at>world.net of the spectrum on a wall momentary operation when Tx button is http://www.oatleyelectronics.com pressed. 1 X 3ch transmitter plus 1 X4ch when placed in sunlight $12.50 major cards with ph. & fax orders, We also have a small Quantity of very receiver:$50 extra Tx $15 is req. to access the fourth relay. 12V operation. (K39) $70 large prisms “RING FOR DETAILS” Post & Pack typically $6 OATLEY ELECTRONICS LARGE 70mm HIGH 7DIGIT 7 SEG. Std. LED DISPLAY PCB ASSEMBLY. (no data available) JUST $20 (Dl2) FREE ADS ON OUR WEB SITE FOR COMPANIES & INDIVIDUALS CONDITIONS APPLY. E-Mail us. E-mail: oatley<at>world.net http://www.oatleyelectronics.com NEW SUPER LOW PRICE + LASER AUTOMATIC LASER LIGHT SHOW KIT: MKIII. Automatically changes every 5 - 60 secs, & is adjustable. Each motor has 8 speeds, one motor is reversible, & one can stop. 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. $15 $59 **SPECIAL**SPECIAL**SPECIAL** FOR $1 EXTRA WITH EACH ORDER WE WILL SEND WIRING KIT !!! Great for cars, radios mobile phones, fog lights etc. 4 colours, 2 guages of wire, Spade connectors, fuse holders, fuses. 17+ mtrs. of wire. Limited offer!!! just $1 UHF DATA TRANSMISSION Stamp sized Xtal locked 433.9MHz superhetrodyne receiver module $25 Small matching transmitter kit: $12 (K122) $20 $18 $40 ** 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. Performs better than most cheaper models. 42mm With: Pinhole (60deg.), 78 deg.; 92 deg.; 120 deg.;$89 or 150 deg: $104 32mmWith: Pinhole (60 deg.), 92 deg.;120 deg.;$110, 150 deg: $125 VERY EFFICIENT WHITE LIGHT - LCD DISPLAY: (ref. EA.) Brand new Sharp 640 x 480 LCD display which features an easily removed very efficient cold cathode Fluorescent lamp 5mm X 150mm Produces useful white light at only about about 1-3W AC input!, 10000 hour life! Display + Backlight Inverter Kit (Needs 12V-150mA): (D11) $17 (Data : $2) SOLID STATE 4-6A PELTIER EFFECT COOLER / HEATER 3.3A<at>14V(GP1) PELTIER: $27, 6A <at>15V(GP2) Peltier: $35, both are approx. 40X40X4mm, temperature controllable by reducing supply voltage /current, will even work from a 1.5V battery!! With data sheet, diagram & circuit for a fridge / heater. IR RECEIVER FRONT END MODULE Contains an IR receiver diode, amp tuned to 38KHz, a bandpass filter, an AGC section & detector circuit. $2 Ea or 10 for $15 BRAND NEW STD LCD DISPLAYS 1 line x 16 . : $16 (D03) 2 line x 16 . (Dl4) with LED back-light:$24 **** 240V 6” FANS **** Good but limited qty. These fans are recovered items but are almost new & in excellent condition. Just $6 Ea. or 3 for $12 SC-NOV-98 This view shows the completed Poker Machine with an 8888 winning jackpot number displayed. The small 7-segment LED displays show the payout. Build Your Very Own Poker Machine Got a gambling habit? Losing thousands? Then rush out and buy the bits for this poker machine. You can play to your heart’s content and never lose your shirt. You can even invite all your friends to play and they won’t lose their shirts either. Design by ANDERSSON NGUYEN With the abundance of poker machines available in clubs, pubs, casinos and various gaming rooms, many of us would have come in contact with one at some time in our lives. This project lets you build your very own 4-digit poker machine, utilising super large 7-segment displays. The circuit 36  Silicon Chip also has a score board to let you keep track of your winnings. In addition, the circuit boasts flashing LEDs to indicate the winning combinations (see Table 1). The points given for each winning combination can also be seen in Table 1. With any four of a kind winning combination, the decimal points of all the super large 7-segment displays light up consecutively, giving a chase effect. Four zeros or four 8s will result in all four digits flashing. Clearly, that’s cause for celebration and while you won’t have won a fortune you won’t lose it later in the session either. The only other hobby poker machine circuit presently available is featured in the Dick Smith Electronics publication “Fun Way into Electronics” Volume 3. That circuit involves only two digits and is not nearly as complicated as the one presented here. This circuit gives the hobbyist an appreciation of how both digital circuits and the one-armed bandit works. This Poker Machine consists of two large PC boards sand­wiched together. The top board contains all the 7-segment dis­plays and their driving circuit while the lower board contains all the counters. Circuit details Because it is so big, we have had to split the circuit diagram into two sections and even then, it takes up the best part of four pages in the magazine. Fig.1 is the circuit of the main board and includes the counters and magnitude comparators, while Fig.2 is the circuit of the display board. While the whole circuit appears extremely complicated at first glance the majority of it consists of repeating units. In explaining the circuit operation we will need to jump from Fig.1 to Fig.2 and back again so here goes. Let’s start with Display 1 (DIS1) which is shown on Fig.2 but is driven by IC1, a BCD to 7-segment decoder/driver, on Fig.1. There is no need for current limiting resistors since each segment consists of four LEDs in series and the total supply voltage is only 9V. The BCD input to IC1 is derived from one section of IC2, a 4518 dual BCD (binary coded decimal) counter. The clock pulse to pin 1 of IC2 (CK1) Table 1: Winning Combinations Combination Type Examples Credits 8 4 2 1 4514 Decoded Outputs Comparators Input To 4514 LED Lit XXYZ 1 0 0 0 1 1 1 Pair YXXZ 1 0 0 1 0 2 1 Y ZX X 1 0 1 0 0 4 1 Pair In A Pair XYYZ 10 1 0 1 0 10 2 Two Pair XXYY 100 0 1 0 1 5 3 XYXX 1000 1 1 0 0 12 4 XXYX 1000 1 0 0 1 9 4 XXXY 10000 0 0 1 1 3 5 YXXX 10000 0 1 1 0 6 5 XXXX 100000 1 1 1 1 15 6 8888 +1000000 1 1 1 1 15 8 0000 + 10000000 1 1 1 1 15 8 Three Of A Kind Triple Four Of A Kind* * B onus comes from IC11, a 4046 phase locked loop which is being used simply as a VCO (voltage-controlled oscilla­ tor). R2 & C1 set the frequency range. C2 & R3 form an RC circuit such that the voltage input to pin 9 of IC11 varies with time. As the voltage at the resistor-capacitor junction decreases, Fig.1 (following page): this is the circuitry for the main board. It may look complicated but it mostly consists of repeating blocks. BELOW: the circuitry is built on two PC boards – a main board and a display board. The full construction details will be published next month. November November 1998  37 1998  37 38  Silicon Chip November 1998  39 so does the oscillator frequency. This makes the frequency high to begin with and then reducing, to give the effect of slowing rolling barrels of a poker machine. Transistor Q9 serves to discharge the 100µF capacitor C2 every time the Play switch is activated, so that the 40  Silicon Chip VCO output is running at the highest set frequency with each throw. The duration for which counter IC2 is active is determined by one of the two dual retriggerable monostables in IC12. R5 & C3, connected to pins 1, 2 & 3 of IC12, set the time for which output Q1 (pin 6) remains high. When it goes low, the counter is disabled and count is halted. This gives the basis for the dis­play mechanism. Similar circuitry is used to drive Display 2 (DIS2). IC3, IC13 and the other halves of IC2 and IC12 are involved instead and the capacitor and resistor values are altered such that the rate of change of count of DIS2 is slower than DIS1 and stops at a later time. DIS3 and DIS4 are driven by circuitry almost identical to that used for DIS1 & DIS2, again with alterations to resistor and capacitor values such that DIS3 stops counting before DIS4 but after DIS2. In driving the displays this way, random number combinations are generated. To obtain a sound effect which suggests the rolling of barrels, the VCO output of IC16 feeds to IC10a, a dual JK flip­flop. This drives a piezoelectric transducer to produce a click­ing sound for every count advance of the last display. The sound is stopped at the same time as count is halted by holding the reset input of the flipflop high when pin 9 of IC15 goes high. Magnitude comparators IC7, IC8, IC9 & IC17 are magnitude comparators and these compare the value of numbers displayed by DIS1 & DIS2, DIS2 & DIS3, DIS3 & DIS4, DIS4 & DIS1 respectively. This is done by comparing the BCD outputs of the respective 4518 counters and one can now appreciate why single counter/7-segment driver ICs (eg, 4026) were not used. The magnitude comparators are always enabled, with their “A = B” outputs going high whenever the two numbers being compared are equal. This may occur many times before all counting ceases. The four “A = B” outputs of the magnitude comparators are fed to IC20, a 4514 1-of-16 decoder and this device decodes and reg­isters the different winning combinations. Once all counting has ceased, the outputs of the magnitude comparators are fixed, dependent on the values in their respec­tive displays. For example, if DIS1, 2 & 3 are all equal, then IC7’s and IC8’s outputs will be high, whereas IC9’s and IC17’s outputs will be low. This represents a binary equivalent of decimal 3 at the inputs of IC20. Therefore, pin 8 will go high when the device is enabled by bringing the INH & FOLLOW pins (1 & 23) low. This is achieved by feeding the Q2bar output of IC15 (which goes high after all counting has ceased) into a delay circuit consisting of Schmitt trigger IC23a, resistor R18, capacitor C14 and diode D2. The output therefore goes low. The delay mechanism is necessary because, in addition to normal functioning, the 4518 will advance in count when EN (pins 2 or 10) is brought low whilst CLK (pins 1 or 9) is low. Thus, if IC20 is enabled at the same time as IC5 (4518) is disabled, (bringing EN low), there is a risk that an undesirable count occurs. This would result in two output pulses from IC20 as data fed into it from the magnitude comparators changed at that in­stant. Indeed, even with the delay mechanism in place, undesir­able counts can be observed as rapid advances in count just prior to stopping. Other winning combinations can be seen in Table 1, along with the decoded outputs and points given. As can be seen, there may be several possible outputs for any one winning combination type. The OR gates in Fig.2 (below): this is the circuitry for the display board. It mostly consists of BCD-to-7-segment decoder ICs (IC24IC32) and 7-segment LED displays. The input signals to drive the display board come from the main PC board. November 1998  41 Parts List 1 main PC board, 252 x 154mm 1 display PC board, 252 x 154mm 1 9V 1A DC plugpack supply 1 piezoelectric transducer; Jaycar AB-3440 or similar 1 pushbutton momentary action SPST switch 4 25mm spacers; Jaycar HP-0866 or similar 4 4 x 32mm screws & nuts to suit Semiconductors 2 555 timers (IC22,IC35) 1 4017 divide by 10 counter (IC34) 1 4002 dual 4-input NOR gate (IC18) 8 4026 counter/7-segment drivers (IC24, IC25, IC27-IC30, IC32, IC33) 1 4027 dual JK flipflop (IC10) 4 4046 phase locked loops (IC11,IC13,IC14,IC16) 3 4071 quad 2-input OR gates (IC21,IC26,IC31) 1 4081 quad 2-input AND gates (IC19) 1 4093 quad 2-input NAND Schmitt trigger (IC23) 4 4511 BCD to 7-segment decoder/drivers (IC1, IC3, IC4, IC6) 1 4514 1-of-16 decoder (IC20) 2 4518 dual BCD counters (IC2, IC5) 2 4528 dual monostables (IC12, IC15) 4 4585 magnitude comparators (IC7-IC9,IC17); Farnell 386522 IC21 ‘collate’ these before they are fed into the scoreboard array. IC18a goes high when all inputs are low, corresponding to a ‘0’ count. IC18b goes high when the ‘1’,‘2’ and ‘4’ binary lines fed into IC17 are low. Since the ‘8’ binary line may be high or low, the output of IC18b will be high on both count ‘8’ or ‘0’. These outputs are then fed into IC19a & IC19b along with output 15 (pin 15) of IC20 (which registers four of a kind). The outputs of IC19a and IC19b therefore constitute bonus winning combinations of 8888 and 0000, in 42  Silicon Chip 4 large 7-segment displays; Jaycar ZD-1850 or equivalent (DIS1-DIS4) 8 7-segment displays; Jaycar ZD-1855 or equivalent (DIS5DIS12) 3 red flashing LEDs (LED6,7,8) 2 orange flashing LEDs (LED4,LED5) 3 green flashing LEDs (LED1,LED2,LED3) 1 1N5404 diode (D1) 1 1N4004 diode (D2) 8 BC548 NPN transistors (Q1-Q8) 4 BC337 NPN transistors (Q9Q12) Capacitors 9 100µF 16VW electrolytic (C2, C6, C8-C10, C12, C14, C22, C24) 2 47µF 16VW electrolytic (C3,C4) 7 10µF 16VW electrolytic (C15-C21) 1 4.7µF 16VW electrolytic (C13) 1 2.2µF 16VW electrolytic (C23) 4 0.1µF (C1, C5, C7, C11) Resistors (0.25W, 1%) 4 10MΩ 1 56kΩ 1 680kΩ 1 47kΩ 2 560kΩ 1 33kΩ 1 470kΩ 8 22kΩ 1 150kΩ 2 15kΩ 4 100kΩ 1 1.2kΩ 1 82kΩ 6 390Ω 1 62kΩ 64 330Ω Miscellaneous Tinned copper wire, hook up wire, solder. addition to the six types listed in Table 1. When 8888 is attained, points are given as for 4 of a kind but also a bonus (1,000,000 points) is given. 0000 will attract an extra 10,000,000 points in addition to the points given for an 8888 combination. The score board array is simply eight repeating units of 7-segment displays driven by 4026 ICs and current-limiting resis­ tors, cascaded by a 10µF capacitor, 22kΩ resistor and 2-input OR gates. The respective winning outputs are fed into one input of each OR gate (except the first) and advances the count by one each time a winning combination is registered. The other input to the OR gate is from the divide-by-10 outputs of the previous 4026 IC. This divide-by-10 output goes high on the 9 to 0 transi­tion, stays high from 0 to 4, goes low on the 4 to 5 transition and stays low from 5 to 9. By staying high for count 0 to 4, the divide-by-10 outputs would inhibit the next counting unit from registering a win (positive clock edge). For this reason, the 10µF capacitor and 22kΩ resistor were included to generate a quick positive pulse to register the carry. This pulse would slowly return to ground as the capacitor charges, thereby allowing the count to proceed. This slow return to ground does not affect operation. Capacitor C22 and resistor R28 at pin 15 of the 4026s ensure that all scoreboard displays are reset when turned on. In addition to driving the scoreboard, each winning combi­ nation output drives a flashing LED via a transistor to indicate the win (Q1-Q8; LED1-LED8). Furthermore, the 4-ofa-kind winning combination output is fed into IC23d to get an inverted output, used to enable decade counter IC34. IC34 has its ‘0’, ‘1’, ‘2’ and ‘3’ outputs connected to the decimal points of the large displays and these will ‘chase’ whenever 4-of-a-kind is attained. IC35 provides the clock pulses for IC34. IC34 is self-reset by its ‘6’ output and hence, a delay between each pulse train re­sults. The output of IC19b is also fed into pin 4 (reset) of IC22. Normally, this will be low and so IC22 is in ‘reset’ and its pin 3 is low. IC23b then inverts this and so a positive signal is fed into the blanking inputs of all 4511 decoder ICs. However, when an 8888 or 0000 combination is attained, IC19b’s output will be high, effectively allowing the output of IC22 to act as an as­table and thereby causing all the large displays to flash on and off. This indicates the bonus win. Finally, resistors R29 and R30 light up the decimal points of DIS7 and DIS10, marking the thousand and million places respec­ tively. These resistors may be omitted during construction if desired. Next month we will publish the details of construction and troubleSC shooting. 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. All other issues are currently i n stock. TOTAL $A B INDERS Pl ease send me _______ SILICON CHIP bi nder(s) at $A12.95 + $5.00 p&p each (Australi a only). N ot avail abl e elsewhere. Buy five and get them postage free. e & Get Subscrib ount On c is D A 10% r Silicon e th O ll A e rchandis Chip Me $A SUBSCRIPTIONS  New subscription – month to start­­____________________________  Renewal – Sub. No.________________    Gift subscription  GIFT SUBSCRIPTION DETAILS RATES (please tick one) 2 years (24 issues) 1 year (12 issues) Australia (incl. GST)  $A135  $A69.50 Australia with binder(s) (incl. 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Please have your credit card details ready 44  Silicon Chip 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 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 SATELLITE WATCH Compiled by GARRY CRATT* Changes on PAS-2 for CNN & NHK PAS-2 (169°E) As predicted, CNN moved to 3905MHz vertical polarisation on July 15, vacating the previously occupied transponder (3965MHz horizontal). There are now no horizontally polarised analog sign­als on this satellite. NHK continue to broadcast in analog on 4055MHz vertical polarity and has extended the period of parallel operation to at least this month, according to sources in Japan. The free-to-air digital service “NHK World” is also running on 4035MHz horizon­tal, SR 26470, FEC 3/4. NHK “World Premium Service” operates using PowerVu conditional access on the same transponder. Costs for the “Premium” service are rumoured to be $2350 for the Scien­tific Atlanta IRD required, plus a 3000-Yen monthly subscription fee. Subsequent to the closure of the dedicated “NBC Asia” chan­nel, a new bouquet has appeared at 4093MHz (SR 29473, FEC 3/4, vertical polarity). The new channels include the National Geo­graphic Channel and CNBC Asia. Versions of these channels des­tined for Indonesia, Taiwan and Australia are carried in the 6-channel bouquet. Since July, a new bouquet has been testing on this satel­lite on 3778MHz vertical polarity, SR 6619, FEC 2/3, no CA, NTSC. The new channels list as: ART America, ART movies, RAI Interna­ tional, ART Australia, LBC America, LBC Australia and MCM The Music Channel. At the time of writing, only LNB America was active. GMA Update Email correspondence with GMA indicates that the broad­caster is trying to work out a way of getting their signal back to Australia. The present service on the Agila satellite at 146° is barely receivable in the eastern states of Australia or New Zealand. The broadcaster is now aware in no uncertain terms of the number of viewers affected in Australia, estimated to be several thousand. Asiasat 2 (100.6°E) TVSN has ceased operations on this satellite, apparently as a result of the Asian economic crisis. The program was uplinked from Epping, a suburb of Sydney. Hallmark movie channel has also moved from this satellite, and now appears on Apstar 2R in scrambled format. KIBC, broadcast from the Philippines with Hallmark, remains on Asiasat 2. THAICOM 2/3 (78.5°E) Despite a low look angle to viewers along the east coast (typically 6° above the horizon), strong signals can be observed using a 2.3m dish. Analog signals include Thiacom tests which can be found at 3650MHz and 3686MHz, horizontal polarity. Digital signals include Thai TV5 and Maharishi Veda Vision, broadcast in an MCPC bouquet on 3600MHz, horizontal polarity, SR 26662, FEC 3/4. Cakrawarta 1 (107.7°E) Indonesia’s own satellite (Cakra­ warta 1) has begun S band testing. The downlink frequency is 2540MHz, SR 20000, FEC 5/6. Initial footprint data indicates a 3m dish will be required to receive this satellite along the east coast of Australia. Indone­sian officials are advising that the satellite may not begin commercial operations for some time, due to the general economic situation in Indonesia. In addition, press reports in August indicate that a solar storm has damaged the spacecraft’s electrical system, reducing the expected lifetime of the satellite to just seven years. The satellite will be unable to achieve full operating power during the solar outages which occur for a few days in March and Septem­ber each year. This means that the planned migration of the current C-band “Indo­ vision” pay TV service, carried on the Palapa C2 satellite, could be delayed some months. Intelsat 702 (177°E) Space TV, a Taiwanese pay TV broadcaster operating for the last year on 12.612GHz (SR 26694, FEC 3/4 horizontal polarity), has left this satellite. This means the only free to air broad­caster is Thai TV5, who have changed their operating parameters to 12.650GHz, SR 17800, FEC 1/2. The service is broadcast in PAL and requires a 1.2m dish along the east coast of Australia for good reception. SC *Garry Cratt is Managing Director of AvComm Pty Ltd, suppliers of satellite TV reception systems. Phone (02) 9949 7417. http://www.avcomm.com.au November 1998  53 An FM transmitter for musicians These three FM transmitters all use the same circuit but you can vary the construction to suit your application. One unit is configured as a guitar FM transmitter, one as a handheld wireless microphone and the other for use with a lapel micro­phone. Design by BRANCO JUSTIC This circuit is not new, having been featured previously in the October 1993 issue of SILICON CHIP. However, there have been a couple of minor circuit modifications to tweak the performance, while the PC board has been redesigned to make the unit easier to build. 54  Silicon Chip In particular, the PC board is now single-sided, whereas the earlier Mk.1 version used a double-sided PC board that re­quired soldering on both sides. As with the previous design, the new “FM Microphone Mk.2” was designed by Oatley Electronics and they will be making avail­able a com- plete kit of parts. So which version should you order? Well, you don’t have to worry about that because the kit contains all the necessary parts for each version. It even includes three labels; you simply use the one that’s right for your application. The differences between the three units are really quite minor. In fact, the two wireless microphone versions are identi­cal except that the handheld unit has the microphone attached to the case while the second unit has the microphone attached to a lapel clip. Fairly obviously, the microphone is left out of circuit for the guitar FM transmitter unit and the guitar provides the input signals instead. Physically, all three versions are housed in the same plas­ tic case, which measures 125 x 40 x 24mm Fig.1: the circuit is based on three transistors (Q1, Q2 & Q3). Q1 functions as an audio preamplifier, while Q2 & Q3 form a modulated oscillator with good isolation between the antenna and the tank circuit (L1 and its parallel 1pF capacitor). (length x width x depth). As shown in one of the photos, a standard 9V alkaline battery sits at one end of the case, while the PC board occupies the other end. A miniature slide-switch on the side of the case switches the power on and off. Performance As before, this FM transmitter design features excellent frequency stability. Some FM wireless microphones can be tempera­mental devices to use, particularly as far as frequency drift is concerned and there are several causes for this. The first of these is due to a drop in the supply voltage as the battery ages. The second is due to capacitance effects between the user’s body and the dangling antenna. Third, and not usually recognised, is drift due to change in temperature. When you set up an FM wireless microphone to operate at a particular frequency, say 95MHz, you don’t expect it to drift much. If it only drifts by a small amount, the AFC (automatic frequency control) circuits of your FM tuner should cope with the change in frequency so that the signal is always received clear­ly. But there is a limit to the AFC range of any FM tuner (per­ haps ±100kHz) and beyond that, the signal will start to distort badly and ultimately, will not be received at all. That is why drift caused by body capacitance can be so annoying as it varies all over the place. This design does not have these problems. We tested it in a number of ways, including heating up the PC board with a hot air gun and even then, drift was not a problem. Nor do power supply variations worry it. In fact, drift due to supply voltage varia­ tions of 1V for a 9V supply is quoted as less than 0.03%. The operating range is quoted as better than 100 metres with a good quality tuner. Other relevant specifications are: signal-to-noise ratio >60dB; pre-emphasis 50ms; frequency re­sponse 40Hz to 15kHz. Circuit details Fig.1 shows the circuit which uses three NPN transistors. Transistor Q1 (BC549) is an NPN audio preamplifier stage which steps up the input signal from the electret microphone or from the guitar. The output from Q1 (at the collector) is then coupled via a 0.1µF capacitor and an 8.2kΩ resistor to the Parts List 1 PC board (available from Oatley Electronics) 1 electret microphone insert 1 9V alkaline battery 1 9V battery snap 1 subminiature former with core, can and base (L1) 1 SPST miniature slide switch (S1) 1 50kΩ trimpot (VR1) Semiconductors 1 BC549 NPN transistor (Q1) 2 BF199 NPN transistors (Q2,Q3) Capacitors 4 0.1µF monolithic 1 0.047µF monolithic 2 100pF ceramic 1 33pF ceramic 1 22pF ceramic 2 15pF ceramic 1 1pF ceramic (see text) Resistors (0.25W, 1%) 1 220kΩ 1 8.2kΩ 1 100kΩ 1 6.8kΩ 2 22kΩ 1 1kΩ 1 12kΩ 1 680Ω 1 10kΩ 1 270Ω Kit Availability This FM wireless microphone/ transmitter has been produced by Oatley Electronics who own the design copyright. They can supply a complete kit of parts, as follows: PC board, all on-board parts, a uni­ directional microphone with clip, a surplus plastic case, slide switch, battery clip and stickers. The price is $17.00 plus $5.00 for postage & packing. The company’s ad­ dress is PO Box 89, Oatley, NSW 2223. Phone (02) 9584 3563 or fax (02) 9584 3561. November 1998  55 This view shows how the parts are installed inside the plas­tic case. This is the handheld microphone version, which has the microphone attached to one end of the case. base of Q3 which is the lower half of a cascode oscillator circuit. The cascode configuration, involving Q2 & Q3, is the secret of the circuit’s excellent rejection of body capacitance effects on the operating frequency. The operating frequency is set by a parallel LC network comprising the 1pF capacitor and adjustable coil L1 at the base of Q3. By virtue of the cascode configuration, the components which set the operating frequency are well and truly isolated from the antenna which is connected to the collector of Q2. L1 allows the operating frequency to be set to a vacant spot on the FM broadcast band (88-108MHz). Building it Fig.2 shows the assembly details for the PC board. The assembly is a pretty straightforward process; it’s simply a matter of inserting and soldering each component in turn. The most important point to remember is to keep all the component leads to an absolute minimum length. Because the circuit operates in the FM broadcast band, even short lead lengths have signifi­cant inductance and this can prejudice the performance. If you intend building either of the FM microphone ver­sions, leave trim­ pot VR1 out. Conversely, for the guitar trans­mitter version, include VR1 but delete the 22kΩ resistor on its wiper and delete the microphone. Note that all the resistors are soldered “end-on” to save space on the PC board. The length of the antenna wire is up to you. You can have it short and unobtrusive or long and thereby obtain better range. We suggest a length of about 65-90cm for good range; any longer and the range will be reduced. Once all the parts have been soldered to the board, you are ready to test it and set the operating frequency. For this you need an FM radio. Connect the 9V battery and turn on your FM radio. Now tune across the band until the speaker squeals. The frequency on your dial is now the operating frequency of the circuit. If you want to adjust the frequency of operation, you re­verse the above process. Tune your radio to a vacant part of the band – let’s say this frequency is 99MHz. All you should be get­ting is hiss from the loudspeaker of the radio. Now adjust the slug of coil L1 until you get a continuous squeal from the radio. That’s it, the job is complete. In more detail, the tuning range of Resistor Colour Codes            No. 1 1 2 1 1 1 1 1 1 1 56  Silicon Chip Value 220kΩ 100kΩ 22kΩ 12kΩ 10kΩ 8.2kΩ 6.8kΩ 1kΩ 680Ω 270Ω 4-Band Code (1%) red red yellow brown brown black yellow brown red red orange brown brown red orange brown brown black orange brown grey red red brown blue grey red brown brown black red brown blue grey brown brown red violet brown brown 5-Band Code (1%) red red black orange brown brown black black orange brown red red black red brown brown red black red brown brown black black red brown grey red black brown brown blue grey black brown brown brown black black brown brown blue grey black black brown red violet black black brown SMART® FASTCHARGERS One charger for all your Nicad & NiMH batteries As featured in ‘Silicon Chip’ Jan. ’96 Fig.2: keep all leads as short as possible when installing the parts on the PC board. Note particularly that Q1 is a BC549 type and is different to Q2 and Q3 which are both BF199s. the wireless microphone can be adjusted upwards by removing the 1pF capacitor. With this capacitor in circuit, the tuning range of L1 will be in the lower region of the FM band: from below 88MHz to about 102MHz. With the 1pF capacitor in circuit, the tuning range will be from about 95MHz. You have to decide which portion of the band you want your circuit to operate in and then pull the capacitor out or leave it in. You then adjust the slug of L1 as described above. After you have adjusted coil L1 to your satisfaction, move the microphone well away from the radio so that the acoustic feedback squeal and distortion is no longer apparent. You should now be able to speak into the microphone and your voice should come from the radio with clean reproduction. You can now complete the construction by wiring up the on-off switch and then installing the board and battery inside the plastic case – see photos. The PC board is positioned at the top of the case and is secured using silicone sealant. You will have to drill a hole in the end of the case to accept the lead for the guitar or microphone (lapel version). If you intend building the handheld microphone version, you will need to mount the microphone on the end of the case before installing the PC board. This will involve drilling a small pilot hole (with the two halves of the case attached to­gether) and then carefully reaming the hole to size. Once this has been done, separate the two halves of the case and secure the plastic base of the microphone to the bottom half only using silicone Capacitor Codes  Value IEC Code EIA Code  0.1µF 100n 104  .047µF   47n 473  100pF 100p 101  1 33pF   33p   33  22pF   22p   22  15pF   15p   15  1pF  1p0   1 Designed for maximum battery capacity and longest battery life Charge: Power tools  Torches  Radio equipment  Mobile phones  Video cameras  Radio controlled models  Field test instruments  Lap-top computers  Toys  Dust busters  Others  The REFLEX® charger is powered from a Power Supply (optional) or from 12 or 24V batteries. AVOIDS THE WELL KNOWN MEMORY EFFECT. SAVES MONEY and TIME. Restore Nicads with memory effect to remaining capacity and rejuvenate many 0V worn-out Nicads. CHARGES VERY FAST plus ELIMINATES THE NEED TO DISCHARGE: charge standard batteries in max. 1 hour and the ‘fastcharge’ batteries in max. 15 min. Partially emptied batteries are just topped up. Batteries always remain cool, increasing both the total battery life and the useful discharge time. DESIGNED AND MADE IN AUSTRALIA For a FREE detailed technical description please Ph: (03) 6492 1368 or Fax: (03) 6492 1329 2567 Wilmot Rd, Devonport, TAS 7310 sealant. The PC board can then be installed, as before. You will also have to drill a small hole at the other end of the case for the antenna lead. Drill this hole in the bottom half of the case only, then make a small cutout for the slider of the plastic switch. This cutout can be made by drilling some small holes and then filing the hole to shape. The switch is also secured to the side of the case using epoxy resin. Be careful not to get any of the epoxy inside the switch – it will be ruined if you do. Also supplied with the kit is a small piece of 3mm-thick foam rubber. This should be attached to the bottom of the case at the end opposite the PC board. It’s there to stop the battery from rattling around. Once everything is in place, the two halves of the case can be secured together using the supplied self-tapping screw. This is installed from the back and screws into a central boss in the top half of the case. Finally, fit the appropriate front panel label and SC the job is complete. November 1998  57 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. Regulator for a car battery charger This regulator prevents a conventional battery charger from overcharging a 12V car battery. It is designed to have a maximum insertion loss of less than 0.2V. To achieve this, the series control element is a BUK456-60 N-channel Mosfet (Q1) which has an ON resistance of 0.028Ω and a drain current rating of 52A. The circuit is suitable for chargers rated up to 8A. Depending on the rating, Q1 will require a minimal heatsink or none at all. The Mosfet’s gate requires a positive voltage with respect to its source and DTMF radio alarm system This system was designed to alert the operator of a steam boiler. A handheld radio fitted with a DTMF tone encoder is used by another person to sound the alert if steam pressure drops. IC1 is a DTMF tone decoder with its input (pin 7) connected to the receiver. The BCD outputs of IC1a are fed via AND gate IC2 which gives a high output at its pin 10 when the 58  Silicon Chip this is generated by a 555 oscillator (IC1) operating at 100kHz. It drives a voltage doubler using 1N914 diodes, D1 & D2. A little used feature on the 555 timer is the reset pin 4 which stops its oscillating when it is pulled low. This is used to turn the Mosfet on and off as required. The battery voltage is sensed by IC2, by means of zener diodes ZD3 and ZD4 connected to its pins 6 & 2. These make the circuit switch off at a battery voltage of 14V and switch on at 13V (or less). Pin 7, the discharge pin of IC2, stops IC1 from running by pulling pin 4 low. Over-voltage protection for the circuit is provided by zener diodes ZD1 & ZD2, diode D3 and SCR1. If the input voltage from the charger exceeds 16V, SCR1 conducts to remove the gate voltage to Q1. Finally, protection against reverse connection of the battery is provided by Mosfet Q2. With a normal battery connected, the gate of Q2 is positive with respect to its source and so it is turned on to provide the 0V return for the drive circuitry to Q1. Howev­er, a reverse connected battery reverses the gate voltage to Q2 and it turns off, killing the power to the circuit and no harm is done. V. Erdstein, Highett, Vic. ($45) DTMF character “7” is decoded. This logic high is latched through to pin 1 of IC3a to enable NAND gate IC4a. The same latched signal is invert­ed by IC4c to remove the reset signal on pin 9 of IC7. IC5 and IC6 divide the 3.579545MHz crystal frequency from IC1 down to 1.7Hz at pin 6 of IC6 and this is fed to pin 15 of IC7, to LED2, to pin 13 of IC2 and pin 5 of IC4a. As a result, Q1 and Q2 will pulse the buzzer at 1.7Hz and Q3 will flash the lamp at the same rate, whenever the output of latch IC3 is high. Whenever the reset pin 9 of IC7 goes from high to low, the 4516 counter will count up and its BCD output will cause the outputs of the 4514 BCD-to-decimal decoder IC8 to go high sequen­tially. About five seconds after IC7 has started to count, Q4 and relay RL1 are turned on via the gating diodes at the outputs of IC8. This relay causes the boiler room radio to send an acknowl­ edging DTMF code for about three seconds. The DTMF code is generated by IC9. The whole alarm system can be reset manually by a front panel mounted pushbutton switch, connected to the reset pins of IC3. The manual test button bypasses the DTMF decoder but tests all other functions of the alarm system. P. Howarth, Gunnedah, NSW. ($45) November 1998  59 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 RADIO CONTROL BY BOB YOUNG A mixer module for F3B glider operations; Pt.1 Last month, we described the operation of the basic con­trols on a typical F3B international class sailplane and outlined some of the parameters affecting the design of such a sailplane. In this article, we will present the design for an F3B mixer module for the Silvertone Mk.22 transmitter. This month we will look at a simple F3B mixer module to illustrate some of the techniques used to control an F3B glider. This will highlight the complex nature of the task. At the same time, I will attempt to break the circuit operation down to the smallest sub-module so that these building blocks may be applied to any transmitter utilising half-rail encoders such as the NE5044. The half rail encoder makes possible servo reversing, mixing, etc. To begin with, this task is very definitely governed by the 90-10 rule, whereby 90% of the effort goes into achieving the last 10% of the result. Modern computer-based transmitters at­tempt to supply everything for everyone and in so doing, have often become burdensome to operate. Frustration during programming is quite common and often the desired configuration cannot be achieved due to system limitations. The module to be described will plug into the Silver­ tone Mk.22 mixer expansion port (TB11) to convert it into a fully config­ ured F3B transmitter with very little program­ming left for the operator. In fact, all that is usually required of the operator is to set up the chan- nel allocation and set the direction of travel on the servos. However, by long experience I realise that there will always be someone who will require an extra 10 widgets or a relocated emfanger. So a very high degree of flexibility has been built into the PC board to give virtually no limit upon the mixing possibilities. Multi-point mixing is available on all 24 channels with any channel able to be mixed with any other channel, if sufficient mixers are obtained. For those who take the trouble to understand the nature of the circuit presented and who are prepared to experiment, the possibilities are endless. The standard Silvertone Mk.22 eight channel encoder PC board carries four free mixers (two inverting and two non-invert­ing) while the F3B module features eight mixers and two end-point clamps, all of which may be operated in the pre-programmed or free mode. Thus there are twelve mixers available, which should be more than enough for the average F3B model. Keeping it simple The main difficulty facing the de- This is a single stick version of the Silvertone Mk.22 transmitter. It gives three-axis control (ailerons, elevator and rudder) via the knob on the stick. signer of any complex programmable system is keeping the programming simple and user friendly. This applies doubly to a discrete component system as the programming can very quickly become a nightmare of patch cords and wander leads. The module presented here overcomes this problem with an extension of the original wander lead programming system. To find out more about this concept, the interested reader should refer to the articles describing construction and programming of the Mk.22 transmitter, published in June 1995 and March, April, May, June, July, August and October 1996 issues of SILICON CHIP. This module is designed around a 28-pin socket that mates with the November 1998  63 Fig.1: the F3B module is constructed out of op amp mixers arranged in matched pairs, one inverting and one non-inverting. An inverting mixer will reverse the direction of rotation of the servo whereas a noninverting mixer will not. Two end point clamps are also provided (see text). mixer expansion port (TB11) on the standard Mk.22 trans­mitter encoder board. When used in the pre-programmed mode, simply plugging this module into TB11 converts the Mk.22 into a fully configured F3B transmitter. It features CROW landing con­figuration, launch camber and a novel knob-controlled camber vary facility that allows the wing section camber to be controlled from the front panel in flight. In this instance, one of the standard Mk.22 auxiliary con­trol knobs is programmed as a camber vary control. There is also a flap/elevator compensation mix and a “V” tail mixer set. This completes the basic pre-programmed instruc­tion set and all of these may be preset or switched in or out from the front panel. Sufficient free mixers are available to add in snap flap, ailerons mixed into flaps and coupled aileron/rudder, thus completing the full F3B complement of con­trols. The PC board is small enough to be hard wired into other brands of transmitters using a flexible lead. TB11 contains all mixing points that may be required for other Silvertone modules still in development. However the F3B module only uses about half of these so there are not a lot of connections to make. If more mixers are required, sufficient information will be given in this series to develop your own circuit board layout. The Mk.22 encoder is a voltage-driven unit using op amps and multiplexers, with the op amps referenced to a half rail (+2.5V) divider. Wander lead programming is used 64  Silicon Chip exclusively, with all controls fitted with identical 3-pin sockets to mate with 3-pin plugs on the encoder PC board. Programming is simple and once one channel is mastered, the rest is simple as all 24 channels follow the same layout and rules. Mixing can be achieved by simply coupling one channel to another with resistors but if this is done, reverse mixing will occur in proportion to the ratio of the series mixing resistor. Therefore it is necessary to insert a buffer amplifier in each mixer lead to isolate the stages. However there are applications where reverse mixing may be useful so keep the resistive mixing technique in mind. Likewise, channels may be run in parallel by using a “Y” lead on the input harness. In this case, variable gain is available on each channel, allowing servo travel to be matched precisely. Op amp mixers Essentially the F3B module is constructed out of op amp mixers arranged in matched pairs (one invert- ing and one non-inverting, as shown in Fig.1. An inverting mixer will reverse the direction of rotation of the servo whereas a non-inverting mixer will not. Two end point clamps are provided and these provide a special feature that we will look at later. A high level of consistency has been achieved in the physi­cal layout with the original Mk.22 encoder and as already men­tioned, the 3-pin programming plug has been retained. A novel touch in this module is the way these programming pins are ar­ranged. Each pair of mixers share a common 3-pin input and output plug pair arranged as shown on Fig.1. Not only is this arrangement simple to program but by rotating the wander lead by 180 degrees, each mixer is available for independent use; a novel touch. As indicated on Fig.1, the pre-programmed input and output leads are linked to the centre pin of each 3-pin plug. For the sake of simplicity, the lefthand 3-pin plug is always the input and the righthand 3-pin plug is always the output. This is shown The lefthand 3-pin plug is always the input, while the righthand 3-pin plug is always the output. This is shown in Fig.2(a), with the inverting mixer on the lower half. Thus, to reverse the servo direction, all that is required is for the micro-shunts to be placed on the inverting or noninverting pins, as shown in Fig.2(b) and Fig.2(c). Fig.2(d) and Fig.2(e) show the patch plug options. full travel end-point is used as the flaps-up position, some unwanted mixing will appear in the flaps. To prevent this, the end-point clamp is applied to the flap control. This limits the voltage swing at TB11 to the mid-rail voltage, which makes the “flaps up” position servo neutral. Thus when moving the flap lever past neutral, the servo will stop at neutral as the lever travels to the full position. In other words, the last half of the flap lever travel is lost. This provides a very interesting feature in the Mk.22 for if we plug the auxiliary potentiometer on the front panel onto TB2 of the endpoint module, we now have a very effective camber control. This may be adjusted in flight to optimise the wing camber to the conditions of the day. Again, this is a very novel feature and something which cannot be obtained in a computer-programmed setup. This view (taken with a digital camera) shows the completed module plugged into the Silvertone Mk.22 mixer expansion port (TB11). in Fig.2(a), with the inverting mixer on the lower half. Thus to reverse the servo direction all that is required is for the micro-shunts to be placed on the inverting or non-inverting pins, as shown in Fig.2(b) and Fig.2(c). The micro-shunts may also be replaced with a DPDT switch for remote switching. The micro-shunts are the same as shorting links commonly used in personal computers. You will note that in Fig.2(b) and Fig.2(c), one input and one output pin are left free and by using one of the patch leads described in the October 1996 issue this free mixer may be used for other tasks if required – see Fig.2(d). Alternatively, the pre-programming can be completely disabled by using both mixers as independent units, as in Fig.2(e). If the application calls for a dedicated installation, the header pins can be dispensed with and all programming points may be hard-wired to remote switches. Referring back now to Fig.1, op amps IC3a & IC3b are two sections of an LM324. IC3a is connected as a non-inverting mixer while IC3b is an inverting mixer. One of the problems with this arrangement is the fact that the gain (servo travel) control on the non-inverting mixer is not as flexible as that of the inverting mixer. The inverting mixer gives excellent control from zero to full travel whereas it is not possible to reach zero gain on the non-inverting mixer. Also the gains of the two mixers are not matched and the input and output voltages must be adjusted with series resistors. Even so, the end result is a matched pair over most of the useful range of servo travel. VR2 and VR3 are the master gain controls and provide the servo travel adjustments (ATV – Adjustable Travel Volume). TB4 and TB5 are the input/ output connectors and are physically ar­ranged as in Fig.2(a). That as is all there is to the basic mixer module. In the full circuit to be presented next month, you will find this module repeated four times with slight variations to suit the programming requirements. End-point adjustment The end point adjustment performs a special function in that it acts as a clamp or brake upon the servo, stopping it at a preset point in its travel. In the full module, this is used to clamp servo travel at somewhere around neutral and performs the camber control. One of the problems encountered in the discrete encoder is that mixing is referenced to neutral which is the half-rail position. As the servo travels further away from neutral, the mixing becomes more noticeable. Now with flaps in an F3B module, mixing is applied both to and from the flap control which is usually the throttle lever on the transmitter. Thus if the flap lever Auxiliary pot setting The setting on the auxiliary pot will define the flaps up position and this may be varied both above and below the neutral flap location. This will provide reflex or camber to the wing airfoil to the deflection best suited to the day. Alter­natively, the camber may be switched in preset amounts by arranging the correct voltages to pin 3 of IC2a. R2 and R4 set the poten­tiometer sensitivity; the larger the value, the less sensitive the potentiometer. TB3 provides a simple reverse for the endpoint adjustment. By moving the micro-shunt on TB3, the polarity of the diode is reversed and thus the endpoint adjustment is applied to either the high or low end as required. The biggest problem in designing a flexible system is that the designer must allow for the placement of servos in the model. There is absolutely no way of knowing which direction the servo will travel in, so allowance must be made for servo reversing in all modules. This virtually doubles the complexity of any design and can be quite a nuisance at times. Lots of early computer transmitters insisted on defined servo placements and were somewhat restrictive as a result. These modules can be used with most brands of transmitters featuring the half-rail encoder. Next month we will present the full circuit and conSC struction of the module. November 1998  65 Pt.2: By JOHN CLARKE AC millivoltmeter measures down to one microvolt If you need to measure wideband audio signals up to 200kHz and down to around 1µV, this project is for you. Last month we presented the operating features and circuitry. This month we present the construction and setting up details and give some practical tips of how to use the unit when testing audio equipment. O UR NEW AC Millivoltmeter has been designed for ease of construction and a minimum of internal wiring. To facilitate this, we have produced a front panel PC board onto which mount the switches, potentiometer and input sockets. This board is soldered to the main PC board to complete all the connections between them. 66  Silicon Chip Construction of the AC Milli­ voltmeter involves assembly of the PC boards, drilling out the front and rear panels of case, mounting the hardware and a small amount of wiring. Most of the components for the AC Millivoltmeter are mount­ed on the two PC boards. The main PC board is coded 01510981 and measures 212 x 142mm while the front panel PC board is coded 01510982 and measures 202 x 73mm. The two PC boards are soldered together at right angles and they fit in a plastic instrument case measuring 260 x 190 x 80mm. You can begin construction by checking the PC boards for any shorted or broken tracks and for undrilled holes. The holes for the rotary switches on the front panel PC board and the Attenuator resistors The resistors for the attenuator switch are mounted on both sides of the PC board. Insert the 100kΩ, 10kΩ, 1kΩ, 100Ω, 10Ω and 2.2Ω resistors into the allocated positions from the front of the PC board and solder in position. Then cut the leads at the back of the board. The 8.2MΩ, 820kΩ, 82kΩ, 8.2kΩ, 820Ω and 2.2Ω resis­tors mount on the copper side of the PC board directly behind the previously mounted values. You will need to insert PC stakes at all wiring positions on the main PC board. There are four more mounted near IC1 to support the PC board shields. On the front panel PC board, stakes should be inserted at the input and oscilloscope output termi­ nals, for switch S4, for pot VR4 and at the wiring points for IC8. Mount the PC stakes associated with IC8 from the rear of the PC board so that they do not protrude too far on the component side. This must be done to provide clearance for the panel meter. Also there are three PC stakes on the front panel board for securing the shields which we’ll talk about later. Next, insert the ICs making sure that you place them in their correct positions with the orientation as shown. All ICs on the main PC board are oriented in the same direction. Diodes D1-D8 and ZD1 can then be mounted, paying attention to their orien­tation. REF1 can also be mounted next, as well as the two regula­tors REG1 & REG2. Note that the 7815 (REG1) is located closest to the edge of the PC board. Fig.1: the component layout for the front panel PC board. Note that six resistors associated with the attenuator switch S1 are mounted on the copper side of the PC board. Note the shield for the attenuator switch. fuse clips (F1) on the main PC board should be drilled out to 1.5mm (1/16"). Also, there should be 3mm (1/8") holes for the corner mounting positions on the main PC board. The holes for the PC stakes should be a tight fit before they are soldered, so that they are not likely to loosen when wires are subsequently sol­dered to them. Start assembly of the PC boards by inserting all the links and resistors. The component overlay for the front panel board is shown in Fig.1, while Fig.2 has all the details for the main board. Table 1 shows the resistor colour codes, to help you select the correct value. Alternatively, you can use a digital multimeter to measure each resistor before it is inserted. You can insert the capacitors next. Table 2 shows the IEC and EIA codes which may be on the MKT and ceramic types. The electrolytic types must be inserted with the correct polarity although that is not important with the bipolar (BP) or non-polarised (NP) types. Next, insert all the trimpots. Make sure you insert each one in its correct place. Often these will be marked with EIA codes rather than the resistance value. Table 3 shows the codes. The fuse clips are best inserted with November 1998  67 Fig.2: this is the component layout for the main PC board. Note that those capacitors marked “NP” are non-polarised and may be installed without regard for polarity; ie, they can go in either way around. A shield must be installed, as shown in the righthand bottom corner, to prevent hum and noise pickup by op amp IC1. 68  Silicon Chip Resistor Colour Codes   No.    1    1    1    1    1    1    7    1    1    3    1    1    2    1    4    1  16    1    2    2    1    2    5    1    3    1    1    2    3    1    2 Value 8.2MΩ 2.2MΩ 1MΩ 910kΩ 820kΩ 560kΩ 100kΩ 82kΩ 62kΩ 51kΩ 47kΩ 36kΩ 22kΩ 20kΩ 18kΩ 15kΩ 10kΩ 8.2kΩ 6.8kΩ 5.6kΩ 4.7kΩ 3.9kΩ 3.3kΩ 2.2kΩ 1kΩ 820Ω 470Ω 100Ω 47Ω 10Ω 2.2Ω the 2AG fuse clipped between them first. Push the clips into the holes in the PC board as far as they can go before soldering them into place. Rotary switches You will need to cut the shafts for the three rotary switches to a length of 10mm while the potentiometer (VR4) shaft should be cut to a length of 15mm. Before the switches are installed, you need to set them for the number of positions required; ie 6-position, 3-position or whatever. This is done by first removing the nuts for each rotary switch and taking out the locking pin washer. Rotate each switch shaft fully anticlockwise. With switch S1, insert the locking pin washer in the 4-Band Code (1%) grey red green brown red red green brown brown black green brown white brown yellow brown grey red yellow brown green blue yellow brown brown black yellow brown grey red orange brown blue red orange brown green brown orange brown yellow violet orange brown orange blue orange brown red red orange brown red black orange brown brown grey orange brown brown green orange brown brown black orange brown grey red red brown blue grey red brown green blue red brown yellow violet red brown orange white red brown orange orange red brown red red red brown brown black red brown grey red brown brown yellow violet brown brown brown black brown brown yellow violet black brown brown black black brown red red gold brown 5-Band Code (1%) grey red black yellow brown red red black yellow brown brown black black yellow brown white brown black orange brown grey red black orange brown green blue black orange brown brown black black orange brown grey red black red brown blue red black red brown green brown black red brown yellow violet black red brown orange blue black red brown red red black red brown red black black red brown brown grey black red brown brown green black red brown brown black black red brown grey red black brown brown blue grey black brown brown green blue black brown brown yellow violet black brown brown orange white black brown brown orange orange black brown brown red red black brown brown brown black black brown brown grey red black black brown yellow violet black black brown brown black black black brown yellow violet black gold brown brown black black gold brown red red black silver brown Table 3: EIA Trimpot Codes Table 2: Capacitor Codes  Value IEC EIA  0.22µF 220n 224  0.15µF 150n 154  0.1µF 100n 104  0.047µF   47n 473  .0027µF   2n7 272  .001µF   1n0 102  47pF   47p   47  39pF   39p   39  6.8pF   6p8  6.8 “6” position and replace the nut. Then check that this switch only rotates to six positions. Similarly, switch S2 has  Trimpot Resistance EIA Code   VR1   100Ω   101    VR2   100kΩ   104   VR3   10kΩ   103   VR5    5kΩ   502 its locking tab washer inserted in the “3” position so that it can be rotated to three positions. Switch S3 has its locking tab washer inserted in the “2” position for 2-position operation. When you insert the rotary switches into the holes on the PC board, make sure that you do not stress the pins. If the switch is difficult to insert, check November 1998  69 Fig.4: the wiring details for the AC Millivoltmeter. The various Earth connections are most important if minimum noise pickup is to be obtained. The front and rear panels must also be securely earthed to ensure electrical safety. 70  Silicon Chip Fig.3: these diagrams show the connections to the two different LCD panel meters that can be used with the AC Millivoltmeter. that the holes are large enough and that the switch body is rotated so that the contact wiper pins are aligned correctly with the holes on the PC board. The terminals of potentiometer VR4 are soldered to three PC stakes and these secure it in position. You make the installation more rigid by using a drop of super glue between its case and the PC board. Switch S4 can be mounted in one of two ways. If you have a PC-mount version you can solder its terminals directly to the PC board. Otherwise, you will need to solder it to three PC stakes. Cut these down almost flush with the PC board so that the switch sits as low as possible. Connecting the PC boards As mentioned above, the front panel PC board is soldered at right angles to the main PC board. To do this, place the main PC board in position in the base of the case. Check that none of the integral standoff pillars are preventing the PC board from sit­ting on the four corner pillars. The unused pillars can be cut down with a large drill to prevent them fouling the underside of the PC board. Now place the front panel PC board at right angles to the main PC board so that its lower edge sits on the base of the case. Check that the edge is not sitting on a raised rib section; some cases have ribs and others do not. If a rib is in the way, you can remove it with a sharp chisel. Mark each end of the front panel PC board where it meets the main PC board. Then remove both PC boards and turn the main PC board upside down. Align the two PC boards so that the copper patterns for each match up and the markings are in the correct position. The alignment will mean that the front panel PC board overhangs the main PC board by about 20mm at one end. You can see this in the photos. Temporarily tack solder the two boards together at right angles in a couple of positions on the large copper areas and check that the positioning is correct when placed Below: this photo shows the front panel board before the shields are installed around the attenuator switch on the lefthand side. Note that some of the attenuator resistors are installed on the copper side of the front panel board. November 1998  71 The two boards are soldered together at right angles and the shields installed around IC1 before the whole assembly is in­stalled in the case. Note the earth leads to the shield on the top of the main PC board and to the ground plane underneath this board. in the case. Then solder the remaining connections. Make sure that all connec­tions are soldered to ensure circuit continuity. Copper shields We’ve have mentioned the copper shields previously but only in passing. Because the AC Millivoltmeter is built into a plastic case, it has no inherent shielding against hum and other inter­ fering signals. Therefore we have found it necessary to mount a shield underneath the main board and also around the input op amp, IC1. Smaller shields are also required for the front panel PC board. We made our shields from copper laminate but you could also use flat tinplate if that is more convenient. We made the top shield from two pieces of copper laminate (ie, blank PC board) measuring 25 x 50mm. They are soldered at right angles and to the PC stakes on top of the main PC board. 72  Silicon Chip The shield for the underside of the main PC board measures 80 x 60mm and is located directly under IC1 and fuse F1. It has two 8mm holes drilled near one edge and these fit over the inte­gral corner pillars on the input side of the main PC board. The shield should be placed copper side down to avoid shorting the underside of the PC board. Front panel shields The two shields for the front panel PC board are mounted near the input socket, as shown in Fig.1. Only solder the side shield (30 x 15mm) in place at this stage. The other shield, measuring 65 x 15mm, is soldered in place after the input socket is connected. Front and rear panels The aluminium front and rear panels can now be drilled out. The rear panel requires holes for the transformer, insulated terminal block, Earth terminal and the cutout for the fused IEC mains socket. This cutout can be made by drilling a series of holes around the cutout border and removing the inside piece. The hole can then be filed to shape. Two holes are required for the mounting screws. Install all the hardware in place with screws and nuts. The front panel requires holes for the switches, potentiom­eter, LED bezel, input sockets and the Earth solder lug, plus a rectangular cutout for the panel meter. Use the front panel artwork as a guide to drill the holes. Once the panel is drilled out you can attach the front panel label. The Jaycar panel meter is supplied with a front bezel which secures it in place. If you are using the Altronics meter, it is designed to be fitted in the panel without a bezel. It can be secured with a screw and nut on each side of the meter or by using a dab of contact adhesive. The input sockets must be isolated from the panel using an insulating kit. This can consist of two fibre washers and a short length of plastic tubing. Secure these in place and do not forget Parts List For AC Millivoltmeter 1 PC board, code 01510981, 212 x 142mm 1 PC board, code 01510982, 202 x 73mm 1 shield PC board, 80 x 60mm 2 shield PC boards, 25 x 50mm 1 shield PC board, 65 x 15mm 1 shield PC board, 30 x 15mm 1 front panel label, 249 x 76mm 1 plastic instrument case, 260 x 190 x 80mm 2 aluminium front and rear panels to suit case 1 31/2-digit LCD panel meter (see text) 1 2855 30V centre-tapped mains transformer (T1) 1 IEC 240V fused panel-mount male socket 1 IEC 7.5A mains power lead 1 2-way insulated terminal block 1 SPST mains rocker switch with Neon indicator (S5) 1 PC-mount 2-pole 6-position rotary switch (S1) 1 PC-mount 1-pole 12-position rotary switch (S2) 1 PC-mount 3-pole 4-position rotary switch (S3) 1 PC-mount SPDT toggle switch (S4) 1 16mm 50kΩ linear (B) potentiometer 4 knobs to suit 2 insulated panel-mount BNC sockets 1 5mm LED bezel 5 M3 x 12mm screws 4 M3 star washers 5 M3 nuts 2 M4 x 12mm screws 2 M4 star washers 2 M4 nuts 4 self-tapping screws 4 crimp or solder lugs 2 2AG fuse clips 1 2AG 1A fast-blow fuse (F2) 1 2AG 630mA fast-blow fuse (F1) 1 500mm length of brown 240VAC 7.5A mains wire 1 250mm length of blue 240VAC 7.5A mains wire 1 250mm length of green/yellow 240VAC 7.5A mains wire 1 250mm length of green hookup wire 1 400mm length of 0.8mm diameter tinned copper wire 1 200mm length of 5-way rainbow cable 31 PC stakes to place the solder lugs beneath the retaining nuts. Make sure that the nuts are tight otherwise the sockets will inevitably twist and break their connections when cables are being connected or disconnected. to the panel meter for the decimal point, BP outputs, battery supply and the IN + and IN- connections. These connection details are shown in Fig.4. Note that the Jaycar meter will require a wire bridge to select the automatic polarity indicator (the minus sign). Also the Jaycar meter has both backplane signals (labelled on and off) Interconnecting wiring Rainbow cable should be attached Semiconductors 1 OP27, LM627 low noise op amp (IC1) 3 LM833 dual op amps (IC2, IC3, IC5) 1 SSM2018 Analog Devices voltage controlled amplifier (IC4) 1 LF347, TL074 quad op amp (IC6) 1 TL072 dual op amp (IC7) 1 4053 3-pole 2-position CMOS analog switch (IC8) 1 LM336-2.5 2.490V reference diode (REF1) 1 7815 15V 3-terminal regulator (REG1) 1 7915 -15V 3-terminal regulator (REG2) 2 1N4936 1A fast diodes (D1,D2) 2 1N4148, 1N914 signal diodes (D3,D4) 4 1N4004 1A rectifier diodes (D5-D8) 1 9.1V 1W zener diode (ZD1) 1 5mm red LED (LED1) Capacitors 2 1000µF 25VW PC electrolytic 1 100µF 16VW PC electrolytic 1 22µF non-polarised PC electrolytic 6 10µF 35VW PC electrolytic 3 10µF 16VW PC electrolytic 1 10µF non-polarised PC electrolytic 1 6.8µF non-polarised PC electrolytic 1 1µF 200VDC metallised polyester (19mm max height) 2 0.22µF MKT polyester 2 0.15µF MKT polyester 5 0.1µF MKT polyester 1 .047µF MKT polyester 1 .0027µF MKT polyester 3 .001µF MKT polyester 1 47pF ceramic 2 39pF ceramic 2 6.8pF ceramic Resistors (0.25W 1%) 1 8.2MΩ 16 10kΩ 1 2.2MΩ 1 8.2kΩ 1 1MΩ 2 6.8kΩ 1 910kΩ 2 5.6kΩ 1 820kΩ 1 4.7kΩ 1 560kΩ 2 3.9kΩ 7 100kΩ 5 3.3kΩ 1 82kΩ 1 2.2kΩ 1 62kΩ 3 1kΩ 3 51kΩ 1 820Ω 1 47kΩ 1 470Ω 0.5W 1 36kΩ 2 100Ω 2 22kΩ 3 47Ω 1 20kΩ 1 10Ω 4 18kΩ 2 2.2Ω 1 15kΩ Trimpots 1 100kΩ horizontal trimpot (VR2) 1 10kΩ horizontal trimpot (VR3) 1 5kΩ horizontal trimpot (VR5) 1 100Ω horizontal trimpot (VR1) Miscellaneous Heatshrink tubing, cable ties, solder, etc. which must be wired. The Altronics meter does not require a bridge for the minus sign or the backplane signal to turn off a decimal point. Place the front panel over the front panel PC board and wire the input socket and oscilloscope socket to the PC pins on the board using short lengths of tinned copper wire. November 1998  73 The rear panel of the AC Millivoltmeter is bare except for the IEC mains socket. Use cable ties to keep the mains wiring neat and tidy and be sure to insulate the mains switch and IEC socket connections using heatshrink tubing. The 65mm long shield can now be attached by soldering it to the side shield and PC stakes. Fig.3 shows the details of all the remaining wiring. The mains wires must be 240VAC-rated. Heatshrink sleeving should be placed over the terminals of the IEC socket and mains switch (S1). The Earth wires must be the standard green/yellow striped wire and are terminated to solder or crimp lugs. These lugs are secured to the panels with a screw, nut and star washers. Tie the mains wires together with cable ties at the switch and the IEC socket. A tie should also be placed around the wires entering the terminal block. Testing When you have completed construction and wiring, check your work carefully for mistakes. In particular, 74  Silicon Chip be sure that the ICs are oriented correctly and that each regulator is in its correct position and orientation. Now apply power and check that the Neon glows in the power switch and that the display is on. Check voltages on the circuit using a multimeter. Clip the negative lead of your multimeter to the metal tab of REG1 and measure the supply pins for each IC. IC1 should have +15V at pin 7 and -15V at pin 4. IC2, IC3, IC5 and IC7 should have +15V at pin 8 and -15V at pin 4. IC4 should have +15V at pin 2 and -15V at pin 16. IC6 should have +15V at pin 4 and -15V at pin 11. Check that the voltage at the cathode of ZD1 is about 9V. Now check that the display is operating correctly. Set the dB/V switch to read Volts and rotate the attenuator to check that the decimal points change. The righthand decimal point should be on when the dB/V switch is set to dB. Check your wiring if this is not correct. Calibration Set the attenuator switch to 200V and the dB/V switch to Volts. Adjust trimpot VR5 so that display shows 00.0V. This is the offset adjustment to zero the display. You will require an AC signal source to calibrate the millivoltmeter. Apply a 1V RMS sinewave to the input. This can initially be checked for level using a multimeter set to read AC volts. Set the attenuator to 2V and adjust VR1 so that the panel meter shows 1.000V. If you have an oscilloscope you can check that the waveform at the CRO socket is about 280mV p-p. If your AC signal source has other output ranges you can check that the Millivoltmeter reads accurately at other attenua­tor settings. The dB linearity needs to be adjusted so that these read­ings are accurate. Fig.5: this is the actual size artwork for the main PC board. Check the board carefully for etching defects before installing any of the parts. November 1998  75 Fig.6: these are the actual size artworks for the front panel PC board and the main shield which is installed underneath the main board. The BNC inputs are wired directly to the front panel PC board. It is important that the retaining nuts are tight other­wise the sockets will tend to rotate when cables are being con­nected or disconnected. It can be done with a 1V RMS source or via a signal generator which has calibrated attenuation ranges. Select the 2V range on the attenuator and apply a 1V signal. Now select the dB measurement and adjust the set level pot so that the reading is 00.0dB. Now move the attenuator to the 20V position and then the 200V 76  Silicon Chip position. The readings should be -20dB and -40dB, respectively. Adjust trimpot VR3 slightly clockwise if the readings are low and anticlockwise if the readings are high. Return to the 2V position and readjust the reading for 00.0dB. Check the calibra­tion again on the 20V and 200V positions. Continue the adjustment on VR3 until the readings are accurate. If you have a signal generator with a calibrated attenua­tor, then you can check the calibration by successively attenuat­ing the signal and checking that the readings are correct. Note that an attenuation factor of 3.16 is a 10dB step. A step in attenuation by a factor of 10 is 20dB. You will need to select the 20Hz to 20kHz filter when measuring below about 50dB on any attenuation range. Note also that VR2 must be adjusted correctly before checking any measurement below 50dB. Trimpot VR2 is the last adjustment. It adjusts the refer­ence voltage applied to the IC6a error amplifier. As we know, the circuit operates in a feedback arrangement whereby the voltage controlled amplifier is controlled with the error amplifier so that the signal output after rectifying Fig.7: this full-size artwork can be using as a drilling template for the front panel. AC MILLIVOLTMETER INPUT FLOAT 2mV ATTENUATOR 20mV 200mV 2V EARTH CRO FILTERS SILICON CHIP dB SET LEVEL MEASURE V dB 20Hz-20kHz ‘A’ WEIGHT FLAT 20V 200V When you are measuring audio equipment with this AC Milli­volt­meter there are a few points to note. Firstly, frequency response checks must be made with the filters set to Flat. Other­wise you could be measuring the frequency response of the filters rather than the equipment under test. Signal-to-noise ratio is always measured with respect to a reference signal. When testing amplifiers, the reference level is usually full power output (ie, just before onset of clipping) or 1W. So typically you will adjust the “dB Set Level” control to produce a reading of 00.0 at full power. For line level equipment it is usual to specify the reference at either 1V or 0.775V which is equivalent to 1mW into 600Ω. When measuring the residual noise from a piece of equipment such as an amplifier, it is important to apply a loading resistor to its input. This simulates the source resistance of the normal audio signal generator which may be CD player, for example. A 1kΩ resistor is normal for most audio equipment. After the reference level has been set for a reading of 00.0dB, the applied signal is removed, the input loading resistor is connected and the AC Millivoltmeter’s attenuator is switched down to the 2mV position. It is necessary to count the number of steps that the attenuator is moved from the initial position down to the 2mV position. To obtain the noise figure, add 20dB per step to the reading on the meter. Finally, the earthing can make a difference to the reading. Check that you do not have an earth loop whereby the signal is connected to ground at two different points. You can have the Millivoltmeter grounded or floating, to either ground the signal or remove the ground loop if the equipment under test is also grounded. Note also that the oscilloscope provides the ground to earth. If you do not use an oscilloscope, you can simulate its earthing by connecting the earth of the scope outlet to the mains earth SC on the front panel. OVERLOAD Making measurements POWER and filtering equals the reference voltage level. Now if we short the input to the Millivoltmeter, the vol­ tage controlled amplifier must provide a large amount of gain so that the noise within the Millivoltmeter circuitry equals the reference. If the reference voltage is too high, then the VCA cannot provide enough gain to match it with the noise signal and so we lose control of the feedback circuit. The way to solve this lack of control is to adjust the reference voltage so that the noise produced with the VCA set for maximum gain can match the reference. VR2 adjusts this reference and is adjusted with the input shorted and the attenuator set to 2mV. The filter must also be set to “A” weighting. Now rotate VR2 fully clockwise. Slowly rotate VR2 anticlockwise and watch the reading increase in value. Continue adjustment until the display suddenly increases rapidly and locks up a -1 on the display. Switch off the power and rotate VR2 slightly more clockwise. Switch on power again and check that the reading sits at a stable value. It should be about -66.0dB to -68.0dB. If the reading stays stable, then leave VR2 as set. If the display continues to go to -1, then you will need to readjust VR2. Check the calibration of the dB ranges again before com­ pleting the setting up procedure. November 1998  77 VINTAGE RADIO By RODNEY CHAMPNESS, VK3UG Improving AM broadcast reception; Pt.1 Interference and poor set design have combined to give AM radio a “low quality” image. However, there are lots of things you can do to reduce interference and boost signal quality. There are new FM broadcast radio stations appearing regu­ larly throughout Australia. Conversely, AM broadcast radio is out of favour, with a reduction in the number of AM stations operat­ing. However, many people only listen to AM radio stations, either because they are the only ones available to them, or they carry the programs that they wish to listen to, or because they only have AM radios in the household. Most FM stations transmit in stereo and some AM stations do too. Both AM and FM transmissions are of high technical quality, with wide audio frequency response and low distortion, etc. The highest audio frequency area well separated in terms of frequency alloca­tion. Typically, stations are spaced at least 45kHz apart and usually more than 100kHz apart. This means that even in the most closely spaced parts of the spectrum in Sydney, it is not difficult for the average AM radio to discriminate between the stations. Interference Even so, interference from stations on adjacent channels can be a problem. This usually occurs at night when stations some distance away are received along with the “local” stations. This causes “monkey chatter” and 9kHz beats between stations only 9kHz apart “Many people hold the mistaken belief that AM broadcast transmitters are restricted to a maximum audio frequency of 4.5kHz, to minimise the possibility of interference between sta­tions on adjacent 9kHz channels. ” broadcast by FM transmitters is 15kHz, while the corresponding figure for AM transmitters is at least 10kHz. Many people hold the mistaken belief that AM broadcast transmitters are restricted to a maximum audio frequency of 4.5kHz, to minimise the possibility of interference between sta­tions on adjacent 9kHz channels. Instead, adjacent channel inter­ference is reduced by keeping the radio stations in any particular geographical 78  Silicon Chip and these beats will be heard on the better quality receiv­ers if they don’t have a 9kHz notch filter. If more than one station is assigned to the same channel, the more distant ones can interfere too, even taking over the channel for a short time in some cases. It can be intriguing to listen as several stations fade in and out on the one channel but it’s frustrating for anyone trying to listen to just one of those stations. Electrical storms also often cause interference to AM radio reception, particularly in summer and towards the equator. Unfor­tunately, there are no easy methods that can be used to eliminate this type of interference, although noise limiters can provide some relief. In summary, AM radio suffers from various interference problems and this is why it has lost popularity, particularly for night-time reception. However, some listeners like to log as many distant AM broadcast stations as possible (DX) and these arti­cles, although not specifically aimed at such listeners, will provide ideas that will assist them too. AM tuner quality In most developed countries, there has been a definite swing to FM broadcasting and AM has been relegated to the posi­tion of the poor relation. If a check is made of the specifica­tions of an AM/FM receiver/tuner, it will be noticed that the FM section is usually extremely good in all areas. Conversely, the specifications of the AM section will be markedly inferior to those for the FM section. But that’s not all – the AM section will generally be in­ferior to the sets produced in Australia from the late 1930s to the 1960s. These include both valved sets and the later Austra­ lian-made transistor receivers. These sets were very sensitive and capable of receiving stations hundreds of kilometres away in daylight. And some were designed to have quite reasonable fideli­ty as well. In short, the sensitivity, bandwidth, AGC characteristics, detector distortion, etc, of the average imported set is almost sure to be inferior to the best of those old receivers. The average AM receiver is really quite a poor perform- Fig.1: AM reception can often be improved by running a separate earth lead from the radio’s earth terminal (if it has one) to a metal stake driven into the ground. Note that a .001µF - .01µF capacitor may need to be inseted in series with the lead at the set’s earth terminal – see text. er these days and its inability to reject interference has given AM broadcast radio a reputation for poor quality – which is really not true. Australia no longer has a consumer broadcast receiver manu­facturing industry, so most of our domestic receivers are import­ed from Asia, Europe or North America. Because of their popula­tion densities, they can afford to have many FM broadcast sta­tions to serve their needs, as only relatively short distances need to be covered. The same goes for AM broadcasts. In short, the emphasis in these countries is on FM and in any case, the distance to the nearest FM or AM stations will be quite small. For this reason, the AM sections are designed for urban use only and have low RF/ IF gain, indifferent IF selectivi­ty and usually poor overload characteristics. These sets also have poor RF selectivity (with no RF stage) and an autodyne oscillator/converter which produces significant oscillator har­monics. This in turn can result in considerable breakthrough of shortwave stations into the broadcast band at times. In Australia, the distance between AM broadcast transmit­ters is generally greater due to our low population density. As a result, these imported sets perform poorly in regional areas and on city margins. The only thing going for them is that they are cheap compared to the good AM transistor radios that were pro­duced in Australia. There are other reasons why people listen mainly to local stations, apart from the fact that the receivers now available are poor distance performers. One of the bugbears of AM radio reception is man-made interference. Electrical interference of various sorts is predominantly an amplitude variable phenomena which is readily reproduced by AM receivers. Properly designed FM receivers respond to frequency variations and reject amplitude variations. As a result, they reject most forms of interference, whether natural or man-made. Interference reduction Electrical interference from power lines and various elec­ t rical/electronic devices can be minimised or even eliminated by employing one or more of the techniques described in this and the following article. AM reception can be poor due to the use of mediocre AM receivers, ineffective aerial/antenna systems and the high level of interference in some locations. However, many of the problems can be resolved or at least minimised so that good AM radio reception can be achieved. Interference does not have to be as strong as the station being monitored to be annoying. Many of the broadcast stations that listeners may wish to receive are not all that strong (I listen in daylight to 5CK which is 750km away from Benalla) and hence even weak interference is annoying. Part of the problem is that we belong to the “portable” society, where everything has to be easily transportable. The concept of “portability” is equally applied to radios and so radios designed for the domestic market are generally not provid­ed with an external antenna connection. And if they were provided with one, the design inadequacies would soon become obvious. The most convenient place to put the radio is on the re­frigerator, a kitchen bench or on a workshop bench. Unfortunate­ly, these are usually the worst locations for interference in our homes. The “quietest” place is out in the backyard, away from all power sources, cars in the street, lawn mowers, etc. A few really electrically quiet locations are at the beach, in a row boat at sea or in the outback away from it all. Modern homes are often worse than older dwellings for radio reception. For example, they may have metallised insulation paper in the walls, while the floor and sometimes the ceiling (espe­ cially in units) can be a reinforced concrete slab. This forms a very effective radio frequency (RF) shield, which means radio signals have a hard job getting into the dwelling, except through breaks in the shield and via the electrical power mains. For this reason, placing the radio near a window or near power wiring often improves reception. Interference sources that affect radios within this RF shield include computers, fluorescent lights (particularly the electronic types), food mixers, TV receivers, light dimmers, shavers, electric drills and touch lamps, etc. The interference generated by these sources is easily picked up directly by the radio. Some of it also travels along the mains wiring in the home and then radiates into the radio. It can also travel via the mains and interfere with the radio reception in neighbouring houses or units. Another source of interference is from high-voltage power lines. The interference can be due directly to problems on the mains (eg, arcing in wet weather) or generated by an electrical appliance. November 1998  79 Looking for an old valve? or a new valve? to the set via the external antenna must be much stronger than the signal picked up by the usual loop stick anten­na in the set, otherwise interference may still be a problem. Antenna types BUYING - SELLING - TRADING Australasia’s biggest selection SSAE DL size for CATALOGUE ELECTRONIC VALVE & TUBE COMPANY PO Box 381 Chadstone Centre VIC 3148 Tel: (03) 9571 1160 Fax: (03) 9505 6209 Mob: 0411 856 171 email: evatco<at>mira.net Because of the effects described above and because they don’t know how to overcome interference problems, most listeners give up and listen only to the local stations. However, there are a number of ways that the interference can be dealt with. The source of the interference can be suppressed or ways can be found to minimise the effect of the interference and increase the radio signal into the bargain. The easiest approach (apart from moving the receiver) is to improve the signal so that it overrides any interference or set noise. One approach is to site an antenna (preferably a noise-reducing type) in a relatively noise-free environment and where there is good signal strength. This will usually involve using an outside antenna in the backyard, at least five metres away from any building or electrical catenary wiring. The signal is then fed to the radio receiver via a cable that does not pick up any signals or any interference as it passes through what may be an electrically noisy area. Either a coaxial cable or some form of twin cable can be used. The signal 80  Silicon Chip Two types of external antenna can be used: (1) a loop antenna which responds to the magnetic field component of the radio signal; or (2) a “long” wire antenna which responds to the electrostatic/electric field component of the radio signal. The loop antenna is a little more awkward to install but its advan­tage is that the near field intensity of interference from the magnetic field is much lower than that from the electric field at the same location. In practical terms, this means that the interference level picked up by a loop antenna is much lower than when using a “long” wire antenna – particularly if the antenna cannot be located in a noise-free area. Portable transistor receivers use a loop antenna so they will do a better job of receiving signals in a noisy environment compared to sets using a wire antenna run around the skirting board. However, the loop in the transistor receiver cannot elim­ inate all interference or intercept radio signals if they are almost non-existent. A good earth It is also very important to have a good earth system, to improve the strength of radio signals and to minimise interfer­ence. This is more important with the long wire antennas, although some loop antennas will also benefit from an earth system. It is well known that the earth wire of a 3-pin power socket goes to an earth stake via the switchboard. This earth lead may be up to 30 metres long, or more. However, AC mains sets which have a 3-core lead and an earthed chassis do not seem to general­ly benefit from having an additional earth fitted when an exter­nal antenna is used. In some cases, however, a noticeable improvement in reception quality can be obtained by installing an independent earth system as close as practical to the radio (assuming that the radio has a separate earth terminal). The reason for this is that the mains earth lead is encapsulated with other mains leads and these may have interference on them. This interference will be capacitively and inductively coupled into the earth lead. Therefore, the mains earth cannot be assumed to be free of interference and usually isn’t. An independent earth can help eliminate this interference. A independent radio earth can consist of a pipe driven into moist soil for a distance of at least a metre. An electrician’s mains earth clamp is used to attach a reasonably heavy insulated wire (such as an electrical mains earth lead) to the pipe and the wire is taken by the shortest practical route to where the radio is located. Make sure that the pipe, clamp and cable (where it is stripped at the ends) are free of corrosion. Paint the junction of the cable and pipe to slow corrosion effects. The earth wire should be insulated over its entire length (except at the ends), so that it does not touch other metallic objects; eg, a metallic insulation sheet in the house wall. If it touches these sheets, interference may be produced due to the minute voltage differences between the sheet and the wire. For best performance, the radio should be located near an outside wall so that the earth lead can be kept as short as possible. The longer the earth lead, the less effective it becomes at reducing interference. To eliminate low-frequency earth currents through the set, you can insert a capacitor of between .001µF and .01µF between this lead and the radio’s earth terminal. Fig.1 shows how the earth is arranged (capacitor not shown). In my case, I have a radio earth in my workshop which almost eliminates fluorescent light noise. Another one in the kitchen reduces a myriad of electrical noises that had previously marred reception. Next month A variety of loop and long-wire antennas have been devel­oped over the years and these will be described next month. Some are conventional while others are noise/interference reducing types. One device – the “Radio Reception Booster” (a tuned induc­tive coupler) – can be used with any of the described antennas and markedly improves the performance of sets using loop-stick antennas. No modifications are required to sets that have no external antenna/earth terminals. SC COMPUTER BITS BY GREG SWAIN Windows 98: how to clean install the upgrade version You don’t have to install the Windows 98 upgrade over the top of the existing operating system. Here’s how to get rid of all those redundant files and do a clean install. I have a public confession to make. I was one of the first people to buy Windows 98. No, I didn’t line up at midnight out­side a Harvey Norman store – I wasn’t quite that desperate to try Bill’s latest and greatest – but I was on the phone to a software retailer the very next morning. My aim was to update my computer – a dual-boot Windows 95/Windows 3.11 system. The dual-boot exercise had long since outlived its usefulness and I wanted to reclaim as much hard disc space as I could by getting rid of the now obsolete Windows 3.11. In addition, I could gain extra drive space by running Win98’s FAT32 file system, something that wasn’t available on my old A version of Windows 95. Windows 98 also promised faster performance, a better interface, improved stability and a number of useful disc maintenance utilities that weren’t included in Win95. It also offers web integration and even includes FrontPage Express, an easyto-use HTML editing program that lets you create your own web pages. As well as Windows 98, I also ordered a copy of Norton Uninstall. An uninstall package is virtually a “must-have” item, particularly if you regularly install new software. Norton Uninstall, for example, can completely track a new installation. It then gives you the option of un­installing the new software and undoing any system changes (eg, to the registry) if you strike compatibility problems with the new program. You can only do this for one program at a time, however. Once you’ve finally instructed Norton Uninstall to accept an installation or you tell it to track a new installation, there’s no going back on changes to system files. OK, so I’ve allowed myself to digress and having committed that sin, I’ll digress further. The system that I wanted to upgrade used a Pentium 133 processor, two hard disc drives (1.3Mb & 1.6Gb) and 64Mb of RAM. The machine is a few years old now and I wanted to boost its performance without spending too much money If you have a Dell or Gateway computer, check the relevant company’s web site (www.dell.com.au or www.gw2k.com.au) for Windows 98 upgrade advice on your specific model. November 1998  81 Boot Floppy System Files Autoexec.bat A:\MSCDEX.EXE /D:MSCD001 /L:R /M:8 /V A:\SMARTDRV.EXE 2048 128 PROMPT $p$g Config.sys DEVICE=A:\HIMEM.SYS DEVICE=A:\EMM386.EXE NOEMS DOS=HIGH,UMB LASTDRIVE=Z DEVICE=A:\SBIDE.SYS /D:MSCD001 /P:170,15 /V Fig.1: these are the autoexec.bat and config.sys files used on the boot floppy for my machine. The lines in italic type load the drivers for the CD-ROM drive. Check that the boot floppy works correctly and provides access to the CD-ROM drive before reformatting your hard disc drive. (well, actually I didn’t want to spend any money). Doin’ a deal To cut a long story short, I happened to have a spare Pentium mother­board while a mate had a spare 200MHz AMD K6 chip in his possession. Maaaaate! Yep, we did a deal – my spare moth­erboard plus a couple of other goodies for the K6. When I in­ stalled the K6 on the motherboard in my machine and reset the jumpers so that it ran at 200MHz, I was pleasantly surprised at the difference it made. I didn’t make any measurements but the dif­ference between a 200MHz K6 chip and a Pentium 133MHz processor is considerable. There was just one problem, if you could really call it that. During bootup, the system BIOS insisted that the new pro­cessor was an AMD K5 running at 133MHz – this despite the fact that the processor was really running at 200MHz. Clearly, the BIOS needed to be upgraded to correct this small annoyance and I decided to do just that before installing Windows 98. I’ll talk more about this later. Upgrade options Basically, you’ve got several options when it comes to installing the Windows 98 Upgrade. You can upgrade from Windows 3.1x or from Windows 95, or you can perform a new installation. In my case, I decided to completely trash my existing setup, reformat the drives and do a clean installation. This has several advantages. For start82  Silicon Chip ers, there are no redundant files left on your drives. Theoretically, what you wind up with is a fresh operating system without any of the unnecessary baggage left over from previous system installations and upgrades. A clean installation also provides the opportunity to re­format the disc drives. This not only ensures a couple of healthy drives but also automatically gets rid of any applications that are no longer used. Basically, you can use the new operat­ing system as an excuse to do a full system cleanup. What about the cons? Well, you do have to reinstall all your applications and replace any data files from backups. And that can be a bit tedious if you have to also install patches or updates for your applications. In my case, I simply backed up the files I wanted to keep using a borrowed portable ZIP drive. Boot floppy Because the Windows 98 Upgrade comes on a CD-ROM (you can order floppies if you wish), you must have your CD-ROM drive working in order to install it. And here’s the catch – if you reformat your hard drives, the CD-ROM drive will no longer work because there are no longer any driver files and no operating system to load them. The way around this problem is to make a boot floppy and copy real-mode (16-bit) driver files for your CD-ROM to it. You then create suitable autoexec.bat and config.sys files on this boot floppy, to load these drivers. For those that don’t know how to go about this, here’s the procedure. If you are running Windows 3.11, it’s dead easy. First, create a boot floppy (format a: /s/u) and copy your existing au­toexec.bat and config.sys files to it. Now edit these two files on the floppy disc to remove any unnecessary device driver com­mands, while leaving the lines for the CDROM drive intact. You need to keep mscdex.exe (the CD extension file) in autoexec.bat, plus the relevant CDROM driver file in config.sys. Don’t forget to change the paths in the command lines so that they now point to the root directory of the A: drive, since this is where the drivers will be copied. Next, copy mscdex.exe plus the relevant CD-ROM driver file to the boot floppy. A few other useful utilities can also be copied across at this time; eg, format.com, chkdsk.exe, scan­ disk.exe, attrib.exe and fdisk. exe. It’s also not a bad idea to add himem.sys, emm386.exe and smart­ drv.exe for memory management and to edit config.sys and autoexec.bat to load these (smartdrv.exe will provide caching for the CD-ROM drive and speed up the installation). If you’re currently running Windows 95 the procedure is somewhat different because real-mode drivers for the CD-ROM are not normally part of the installation. Instead, you have to get them from the installation disc that came with the CD-ROM drive. The first step is to make a Windows 95 startup disc and you do this by double-clicking the Add/Remove Programs icon in Con­trol Panel, then clicking the Startup Disk tab and clicking the Create Disk button. When this has been done, make backup copies of your existing autoexec.bat and config.sys files, then restart the computer in DOS mode (click Start, Shut Down and choose “Restart the computer in MS-DOS mode?”). Once you’re at the DOS prompt, go to the root directory of the C: drive and install the DOS-mode CD drivers from the floppy disc supplied with the CD-ROM drive. This will copy all the necessary driver files to a directory on your hard disc and add the necessary command lines to auto­exec.bat and config.sys. You now copy the modified auto­ exec.bat and config.sys to your startup disc, along with the newly installed driver files. As before, you need Choosing the web-style interface for Windows Explorer gives it an updated look that’s more consistent with Internet Explorer’s interface. The Back, Forward and Up buttons make it easy to navigate between folders and you get a thumbnail preview of selected graphics and html files. Windows 98 offers improved disc maintenance utilities, including a Maintenance Wizard that lets you automatically schedule certain tasks. mscdex.exe plus the CD-ROM driver file. You can tell where these files are on the hard drive by looking at the paths in the command lines in autoexec.bat and config.sys. Don’t forget to edit these two files as before, to get rid of unnecessary device drivers and to point the CD-ROM command lines to the drivers on the floppy disc. Finally, reinstate your original config.sys and autoexec.bat files on the C: drive, then restart the machine using the boot floppy. Check that the CD-ROM drive works by inserting a CD-ROM, then typing Dir D: at the DOS prompt, where D: is the drive letter of your CD-ROM. If it works, you’re in business. Fig.1 shows the autoexec.bat and config.sys files used for my machine. Note that the switch /L:R in the mscdex.exe command line means that the CD-ROM drive will be drive R:. If you don’t have this switch, the CD-ROM will assume the next drive letter after the hard disc drive(s). Note that the driver file required for your particular CD-ROM drive will probably differ from that shown in Fig.1. Updating the BIOS OK, so what about that BIOS update, to improve support for the AMD K6 processor? This would have to be done next, before I reformatted the drives. The motherboard is an ASUS brand (model P/I-P55T2P4, to be exact) and their web site URL (www.asus.com) was easy to guess. In fact, this web site is excellent and I soon found the required BIOS update for my particular motherboard. Among the “fixes” listed for the update was support for the AMD K6 processor, so that was encouraging. As well as the BIOS update, I also downloaded a small utility (called pflash.exe) to flash the BIOS, plus a text file with the instructions. Now a BIOS update is quite easy to do but it’s not recom­mended for novices. If you make a mess of things, you can end up with a corrupted BIOS and a computer that won’t boot. The only way out of this sort of mess is to obtain a new BIOS chip from your supplier (or get them to re-flash the old chip if they have that capability). If you can’t get a new BIOS, you’re really left stranded right up that proverbial creek, without a paddle. The best advice here is “if it ain’t broke, don’t fix it”. Anyway, back to the job at hand. Updating the BIOS on the ASUS motherboard first involves changing a jumper to enable the Flash BIOS programming capability. After that, you simply reboot the computer, run the pflash utility and follow the onscreen prompts to re-flash the BIOS. And that solved the problem. When I rebooted the machine, the BIOS now informed me that I had an AMD K6 running at 200MHz. Strangely enough, Windows 95 didn’t take to the BIOS upgrade and refused to load – this despite the fact that a previous BIOS update hadn’t fazed it. Installing Windows 98 With the BIOS upgrade under my belt, I reformatted both hard disc drives (format c: /v /u and format d: /v /u). The /u switch was included to ensure that the drives were formatted unconditionally. This destroys all existing data on the drives and ensures that they cannot be later unformatted. The Windows 98 installation itself is straightforward. The procedure is to boot from the floppy disc, logon to the Windows 98 CD, type “Setup” and press Enter. This starts the Setup Wiz­ard, after which you’re asked to enter the product key (found on the back of the disc sleeve). If you’re installing the Upgrade version, the November 1998  83 Windows 98 lets you can choose a web-style interface for your entire desktop. When you choose this option, the desktop icons appear as web-style hyperlinks which can be activated by a single click. Provided you’re connected to the Internet, the Windows Update feature provides a convenient means of keeping your system up to date. It’s accessed via the revamped Start menu. 84  Silicon Chip Setup Wizard also does an upgrade compliance check, which means that you must have a full version of either Windows 95 or Windows 3.1 on hand. During the compliance check, you’ll be asked to insert either your Windows 95 CD or Windows 3.1 discs. This can be a trifle annoying because, in the latter case, it wants to “see” no less than six floppy discs. Once the wizard is satisfied that you have a “full” version, it proceeds with the installation. I strongly recommend that you select the Custom option when the Setup options dialog box appears. This not only lets you add features that are not installed by default but also lets you delete space-consuming features that you don’t need. At some stage, you’ll also be directed to create a Startup disc so be sure to set aside a clean floppy disc before starting the in­stallation. Don’t imagine for a minute that the whole process will be finished while you have a cup of coffee – you’ll need several cups, in fact. Depending on the speed of your CD-ROM drive, the whole process can take the best part of an hour. During the installation, the Setup Wizard automatically restarts the comput­er several times and there’s a great deal of hard disc activity as the system identifies you hardware configuration and copies the driver files and other system files across. In my case, it all worked perfectly. Windows 98 correctly identified my Diamond Stealth video card, a nonPnP SoundBlaster 16 soundcard and a non-PnP Adaptec SCSI controller and installed the correct drivers for them. It also correctly identified an external modem plugged into COM2 and installed the drivers. By the way, if you are using nonPnP (legacy) expansion cards, be sure to reserve their IRQs in the system BIOS (if you have a PnP BIOS, that is) before installing Windows 98. This must be done for everything to work reliably. By reserving the legacy card IRQs in the BIOS, you let the operating system know which IRQs have already been assigned, thereby leaving it free to correctly assign the remaining IRQs to PnP cards. Further infor­mation on this subject can be found on page 8 of the June 1998 issue. Motherboard manufacturer Asus maintains an excellent web site that lets you easily find and download the latest BIOS updates for their products. What’s it like? Is Windows 98 worthwhile? In my opinion, yes, particularly if you’re currently running the “A” version of Windows 95 or if you have Windows 3.1x. Bear in mind, however, that you need plenty of disc space to install it (around 200Mb) and you should preferably have 32Mb of RAM or more, if your applications demand it. Yes, you can get away with 16Mb but 32Mb will noticeably improve the performance. Based on my own observations, the installation is very stable. The FAT32 converter works like a charm too and I managed to recover some worthwhile space by running the conversion. I’m not too sure about the one-click active desktop option as yet but I’m prepared A good uninstaller is almost a “must-have” item if you intend trying out lots of software. One such uninstaller is Norton Uninstall. It lets you backtrack on your last installation and can do registry clean-ups and lots of other things as well. to give it a go. It’s easy to switch back to the familiar double-click interface if you can’t take to it. Of course, not everyone will experience a hassle-free up­grade, especially if you elect to install over the top of an existing system. You might require an updated driver for your video card or sound card in order for them to work correctly with Windows 98, for example. Suitable updates can usually be down­loaded from the manufacturer’s web site. If you have a brand name computer, check the manufacturer’s web site for upgrade advice. For example, both Gateway and Dell offer Windows 98 upgrade advice on their web sites and even list drivers that you can down­ load to correct any problems with specific hardware items (eg, soundcards and video cards). SC November 1998  85 Pt.9: The Basics Of Luminaires Electric Lighting 86  Silicon Chip Very few lamps are suspended naked in space. For aes­thetic and functional reasons, the lamp is usually mounted within a fixture – a “luminaire” in lighting parlance. The design of the luminaire has a major bearing on its luminous intensity, durabil­ity and appearance. By JULIAN EDGAR ABOVE & FACING PAGE: The same scene, by day and by night. The luminaires used to illuminate this road are the B2224 Series, manufact­ured by Sylva­nia. They use a diecast aluminium chassis, polyethylene injec­tion moulded canopy and acrylic refractor. The refractor is secured with aluminium screws and the optics are silicone gasket sealed. During lamp changes, a wire lanyard holds the refractor in its open position. In this application the luminaires have been fitted with 80W mercury vapour lamps. In addition to having a pleasing appearance, a luminaire must: •  provide electrical connection to the lamp(s);   physically protect the lamp(s); • •  control and distribute the light from the lamp(s);   be • robust; and •  be efficient in use. The wiring used inside a luminaire is normally of the solid core type. Because of its stiffness, fewer ties are needed to hold solid core wire in position and it is easily stripped of insulation. However, where the luminaire is subject to vibration or if the wire will be frequently bent (eg, in an adjustable spotlight), stranded wire is used. The ability of the wiring’s insulation to withstand high temperatures is very important. Not only is the temperature of the air within the luminaire likely to be elevated above ambient but components such as ballasts and lamp holders can become very hot. Generally, PVC insulation with a heat rating of 90°C, 105°C or 115°C is used. In high-intensity discharge floodlights, even higher temperatures may be present. In these lights, silicone rubber (170-200°C) and PTFE (250°C) insulation is used, sometimes with glass-fibre sleeves. Protection of the lamp is also important in many situa­tions. If the lamp is to be used outdoors, for example, the luminaire must prevent the ingress of dust and moisture. As well, it may also be designed to protect the lamp against physical damage; eg, from children playing ball or from vandalism. Dust and moisture protection re- quires that the lamp be fully enclosed, with a light-transmitting front panel fitted. So that the lamp can be changed when it fails, the cover needs to be detachable, necessitating the use of a seal around its aperture. Seals can be made of felt, silicone rubber, norprene, or neo­prene. Fig.1 shows two different sealing methods. Protection against accidental damage and vandalism can be obtained by covering the front face of the This indoors luminaire is designed to add to the appearance of the lamp and to provide a broad spread of light. The lamp should be cleaned at regular intervals, to maintain light output. November 1998  87 luminaire with stain­less steel mesh or by making the luminaire of polycarbonate. This very tough material is available in clear and coloured forms, making it suitable for all parts of the fitting. Light control (a) (b) Fig.1: luminaires located outdoors use sealing mechan­isms that allow them to remain weatherproof while still allowing the lamps to be easily changed. Fig.1(a) shows the waterproof edge seal used in a fluorescent luminaire, while Fig.1(b) shows the notched rubber seal used in a floodlight. (Philips Lighting Manual). Fig.2: a circular reflector gives a broad spread of illuminance when the light source is at the focus, as depicted here. (Philips Lighting Manual). (a) Fig.3: a parabolic reflector with the light source placed at the focus produces a parallel beam of reflected rays. (Philips Light­ing Manual). (b) Fig.4: combined spherical and parabolic reflectors are generally used in the two configurations shown here. In both cases, the spherical reflector diffuses the light from the source prior to reflection off the parabolic portion of the reflector. (Philips Lighting Manual). Fig.5: an elliptical reflector with the light source placed in front of the focus gives a “pinhole” effect and is commonly used in downlights. (Philips Lighting Manual). Optical light control systems range from those that produce an even, well-distributed light to those that direct a defined beam in one direction. Optical devices that are commonly used include: •  reflectors; •  refractors and diffusers; and •  screening devices. There are three different types of reflectors: specular, spread and diffuse. Specular reflectors use a mirror-like sur­face. Materials used in such luminaires include anodised alumini­um, aluminised glass and aluminised plastics. Alternatively, commercial grade aluminium can be clad with a thin layer of very pure aluminium or silver, giving a finish with reflectances of up to 80% and 90% respectively. These reflectors are used where a precise form of light distribution is required, such as in floodlights, spotlights and road lighting luminaires. A number of different shaped specular reflectors are used, including: circular reflectors (Fig.2), parabolic reflectors (Fig.3), combined spherical and parabolic reflectors (Fig.4), and elliptical reflectors (Fig.5). Unlike specular reflectors, spread reflectors do not give a mirror image of the source but the angle of maximum reflected intensity still equals the angle of incidence. A spread reflector gives a very even distribution of light, with the reflecting surface de-emphasising any hot spots caused by manufacturing inaccuracies in the shape of the reflector. Spread reflectors are commonly made from polished alumini­ u m, hammered or moulded into a pattern consisting of small bumps or dimples. Alternatively, the aluminium can be brushed. The spread reflector is used where an even light distribution is required. Diffuse reflectors Diffuse reflectors scatter the light widely. The shape of the reflector has only a general bearing on the resulting light distribution, so sharp beam control is not possible. Diffuse reflectors 88  Silicon Chip are cheaply produced using glossy white-painted steel or white-coloured plastic. This type of reflector is commonly fitted to fluorescent luminaires. Refractors are used to control the direction of the light emitted by the lamp(s), primarily to stop glare. Glare occurs in the viewing angle between 45° and 90° to the vertical axis beneath the luminaire – see Fig.6. Refractors reduce the illuminance in this glare zone, directing the light down rather than out­wards. Most fluorescent luminaires use a refractor consisting of an acrylic or polystyrene panel that is smooth on top and has many small conical prisms on the underside. The refractor fitted to a 2-lamp fluorescent luminaire can have as many as 5000 prisms moulded into it. of the beam is sometimes blocked by a baffle. Luminous intensity distribution Fig.6: direct glare from a lumin­aire is most likely to be a problem at an angle of 45-90° from the vert­-ical. (Murdoch, J., Illuminat­ion Engineering). Screening devices An alternative approach to controlling glare is to use screening devices such as louvres or baffles. These are often used in fluorescent luminaires and Fig.7 shows the screening effect of the reflector used in such a luminaire. Another ap­proach is to recess the luminaire into the ceiling so that the lamp(s) cannot be seen from directions where glare could be a problem. In floodlights, spill light to one side Fig.7: the amount of glare can be considerably reduced by using a screen to obscure the light source. (de Boer, J & Fischer, D., Interior Lighting). Manufacturers generally produce a great deal of photometric data for their luminaires, with luminous intensity distribution being one of the most important. The luminous intensity distribu­ tion curve reflects (pun intended!) the design of the luminaire, being affected by the combination of direct, reflected and dif­ fused light emanating from the luminaire. Fig.8 shows a Sylvania Indy Series luminaire. This large luminaire is designed for high mounting in warehouses, loading bays and industrial plants. It is 545mm high and its spun alumin­ ium elliptical reflector has an external diameter of 420mm. The luminaire can be fitted with lamps of up to 400 watts. The luminous intensity distribution curve is shown in Fig.9 and this shows that most of the light is directed downwards, with very little illuminance at more than 40° from the vertical. As you would expect with a round reflector, the luminous intensity distribution of this luminaire is symmetrical around its vertical axis. A luminaire which is superficially similar in appearance is shown in Fig.10. This is a Sylvania Sylvaglow, designed for mounting at relatively low heights, again in warehouses, facto­ries and so on. Unlike the previous unit however, it uses a combination of spherical and parabolic specular reflectors and is fitted with a diffuser. The luminous intensity distribution curve (Fig.11) shows that the illuminance spread from this luminaire is wider than for the previous case, with effective illumination at up to 50° from the vertical axis. However, the values of luminous intensity are well down over the other Sylvania luminaire, with luminous in­ tensity being traded off against the luminaire’s spread. Light loss If uncleaned for three years, an indirect up-light in a dirty environment will typically have its light output reduced by 55%! It is the average maintained luminance that is the critical factor in assessing the effectiveness of a lighting installation. Light loss occurs through four different factors: •  lamp burn-outs; •  lamp lumen depreciation; •  luminaire dirt depreciation; and November 1998  89 Fig.8: the Sylvania Indy Series luminaire is designed for high mounting in warehouses, loading bays and industrial plants. It uses a spun aluminium spherical reflector and can be fitted with lamps of up to 400 watts. (Sylvania). Fig.9: the luminous intensity distribution curve of the Sylvania Indy shows that most of the light is directed downwards, with very little illuminance at more than 40 from the vertical. (Sylvania). Fig.10: the Sylvania Sylvaglow is designed to be mounted at relatively low heights. It uses a combination of spherical and parabolic specular reflectors and is fitted with a diffuser. (Sylvania). Fig.11: the luminous intensity distribution curve of the Sylva­glow shows that the spread of illuminance is wider than for the Indy. However, the luminous intensity values are much less. (Sylvania). •  room surface dirt depreciation. If a burnt-out lamp isn’t immediately replaced, there will obviously be a noticeable decrease in luminance. In some situa­tions, where replacement may not be immediate, the lighting design needs to take this into account. Even prior to failure, the luminous flux of the lamps will have decreased compared to their new output. As it approaches the end of its life, an incandescent lamp will typically have a luminous flux of only 78-90% of its 90  Silicon Chip “new” figure, while a fluo­rescent lamp may be down to 72%. From this, it follows that if the illuminance is only just acceptable when the lamps are new, it will be quite unacceptable after a few thousand hours of operation. Dirt build-up However, it is dirt build-up on the luminaire that is the single greatest cause of light loss. The rate at which the light output decreases is dependent on the room cleanliness, luminaire design and, of course, on the frequency and thoroughness of lumi­naire cleaning. As an indication, a bare lamp batten in a dirty environment will typically show a decease in light output of 17% after a year without cleaning! An even worse-case scenario is an indirect uplight in a dirty environment. If it’s uncleaned for three years; its light output will typically decrease by about 55%. Make sure that you regularly clean SC your luminaires! 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. Splitting the distribution amplifier I am currently installing a TV network including the dis­ tribution amplifier as described in the August 1996 issue of SILICON CHIP. It appears to be working however after requests by a number of mates for a similar network, a number of questions have arisen. Can the two boards be connected by multi-strand wire rather than coax? Could the masthead board be placed up the mast and the power board be located inside? Would it be better to have two antennas and if so, could they be placed on the same mast? Is there a way to measure the signal loss/ gain? (perhaps using an old VCR tuning section as hiring the equipment appears relatively expensive). (A. W., No address). •  You must use coax cable to connect the two PC boards but they can be separated, with the masthead board near the antenna. If you have two identical antennas, they need to be vertically spaced by at least half a wavelength at a midband frequency, for best results. We would try the system with one antenna first. There is no easy way to measure signal loss or gain although if you have a wideband oscilloscope and a buffer preamp you can make usable measurements in the VHF band. How to cripple Clifford the cricket I have assembled the “Clifford the Cricket” kit as de­scribed in the December 1994 issue and it is operating but I find no delay time when the light is switched off. The cricket comes on almost instantly. Could this be remedied by altering the value of the 100µF capacitor at the input of IC1a? If so, what new value capacitor would be required? (E. R., Melbourne, Vic). •  If there is no switch-off delay then it is almost certain that the 100µF is effectively not in circuit. This could be because the capacitor itself is open-circuit or there is a cold solder joint or broken copper track. Try substituting another 100µF capacitor to see if that fixes the problem. The dangers of over-voltage I work from home repairing electronic items such as VCRs, car stereos and computers, etc. My computer is in our guest room and my guests have complained that the UPS alarm goes off most mornings about 5am or 6am. I thought it was possible that when everybody got up to go to work and put on their electric kettles that the mains voltage was dropping – hence the UPS alarm. I connected my Metex M-3850D multimeter (with RS232 output) up to my old 286 and monitored the voltage early one morning and I found that the voltage is way too high at 260VAC. My Metex meter has been cross referenced with a Fluke 75 (recently cal­ibrated by HP). My questions are these: (1). What damage can the over-voltage do to household appliances and computers? Most computers have 220VAC or 230VAC labels on the rear of them. (2). Are we being overcharged for our electricity as we pay for the kWh used? I have calculated (roughly) that each appliance is using about 18% more power at the higher voltage. (3). Do you have any suggestions as to how to handle my complaint with United Energy here in Melbourne? (C. H., Patterson Lakes, Vic). •  Your complaint about high mains voltage is all too common in rural and semi-rural areas. You will probably Australian Audio Consultants - Sole Australian Distributors P.O. 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HORNSBY 2077 Ph (02) 9476-5854 Fx (02) 9476-3231 find that your local electricity distributor has very long lines and so they keep the voltage high to make sure that the supply at the end of the line is still adequate. It is probable that a higher than nominal voltage does cause more appliance failures but whether it is appreciably higher is anybody’s guess. Certainly, your incandescent lamps will not last long with a mains voltage which is typically 8% high and that may be the biggest cost. Other appliances with filaments, such as picture tubes in TV sets and computer monitors and heaters with spiral wound elements in fused silica tubes won’t last as they should either. You will also be paying more when running heating and lighting appliances since you have no control over this factor. Appliances with thermostats or switchmode power supplies will not use significantly more energy due to the fact that they maintain a specified internal voltage, temperature or whatever. If you are concerned, you have two possible approaches. First, you can write to your local distributor (write a letter, don’t phone – they are more likely to respond to a letter) out­lining the problem and complain to them about reduced incandes­cent lamp life, having to pay for more power than you want and possible increased appliance failure rates. Second, if you are concerned about a particular appliance, you may consider running it from an auto-transformer to reduce the supply voltage. We featured an article on this subject, entitled “Stop Blowing Incandescent Lights” in the January 1997 issue. Problem with 10A speed controller I am writing about the 10A speed controller described in the November 1997 issue of SILICON CHIP. A customer of ours has bought and assembled a kit based on your project. He has used the speed controller on a portable 700W Makita grinder. The BUP213 (IGBT) has failed after only a few hours use. We have replaced the BUP213 for him and it has failed again after a short time. The BUP213 measures low resistance between any of the terminals. Can you advise any additional protection? (J. N., Seven Hills, NSW). •  We are concerned that the Makita grinder may be faulty in some way which causes it to draw very heavy currents. Perhaps it has shorted commutator segments or a shorted winding on the armature (rotor). This could be 4½” METAL CUTTING LATHE (6" with riser blocks) Precision and ruggedness to suit industry, school or hobby use. Over 25,000 sold worldwide. Made in USA 2 year warranty 92  Silicon Chip buys a lathe with $429 drilling tailstock, pulleys and belt, 3 jaw chuck, Jacobs chuck etc. You supply the motor – an old appliance motor will do! Accessories available: Compound slide, 4 jaw chuck, faceplate, collets, milling attachment, and many more. Write or phone for photo brochure and price lists. TAIG MACHINERY 59 Gilmore Crescent. Garran. ACT. 2605. Ph: 015 26 9742 (Business); (02) 6281 5660 (AH); Fax: (02) 6285 2763 indicated if there is excessive sparking on the commutator when running directly from the mains. We cannot suggest further protection measures for the BUP213 as it is already a very rugged device. We have not had any other complaints about failures of the BUP213. We are assuming, of course, that the existing protection components, ZD1, ZD2, D1 & MOV1, are all functioning correctly. High energy ignition worthwhile on bikes Regarding the use of the High Energy Ignition system with motorcycle engines (M. H., Wembley Downs, WA, “Ask Silicon Chip” September 1998), I agree with part of your reply – if the motor­cycle already has a working breakerless electronic ignition then there’s no point in replacing it with an HEI system. However, given the cost of factory replacements for Jap­anese bikes in particular, the HEI system could be an economical replacement for a faulty original unit. But a word of caution before rushing in: many post-1975 Japanese single cylinder bikes use a purpose-built ignition control module, powered and triggered by coils wound into the alternator stator assembly and thus present no easy interface for the HEI. And many small capacity 2-stroke trail bikes have contact breaker points but their application is often more akin to a magneto than a conventional pointsand-coil system. The HEI can be readily applied to most 1960s to early 1970s 4-stroke single, 360° parallel twin and 4-cylinder-in-line motorcycle engines that still have points-and-coil ignition systems. The simple trick for a 360° parallel-twin engine is to use the one HEI unit, built to be triggered by both sets of points, to fire both coils together whenever either set of points opens. When either cylinder is at the end of its compression stroke, the other is at the end of its exhaust stroke, and the “spare” spark fires harmlessly into exhaust gas. The two ignition coils can be connected in parallel – the current limiting of the HEI eases the load on the marginal Lucas electrical systems used on old British bikes in particular. This is not optimum but more reliable running and with indefinite points life is a big improvement on the original Pointless approach to HEI I have reviewed the design for the original ignition system and have concluded that points can still be used if the basics of the Kettering system are retained. The method is quite clear; instead of driving the electronics from the points directly, a suitable transformer is interposed between the point system and the electronics. This transformer must carry an unbalanced direct current of say 100mA and have a primary inductance of say 144mH and a DC resistance of 120Ω. These values can be obtained with a single loop of 10/8/13 “C” core with say 500 turns spread over the two legs. The air gap is adjusted until the inductance is about right and the DC resist­ance can be padded out to 120Ω. The resulting output voltage is about 110V peak about 170µs after the points open. The secondary can be wound with say 25 turns to give about 5V which system! For a much better result, the two 12V coils should be replaced by 6V coils and connected in series. A 4-cylinder engine is just two 2-cylinder engines. Two HEI units can be used to trigger two pairs of coils. Most Japanese 4-cylinder bikes use this principle – they have two “double-ended” coils, each firing two plugs simul­taneously, triggered by two sensors 180° apart on the camshaft. The “spare” sparks go harmlessly into those cylinders on their exhaust strokes. One final caveat: before proceeding, should be ample to drive the input of the electronic ignition unit. With this current and voltage on the points, any semicon­ducting film should be broken down without seriously degrading the long point life occasioned by the low current. Whilst the pressure of my other projects does not permit me pursuing this idea for some time somebody may care to try it out and publish the results of a field trial. I have now experienced two failures of the transistorised ignition system, both being caused by point fouling. Although I have used the power Mosfets, my front end is identical to that specified in your design. The R.A.C. serviceman who attended my breakdown commented that in his experience point fouling was a hallmark of retrofitted electronic ignition systems using points. From my experiences I must therefore conclude that your paragraph on the wetting current in the points-controlled version referred make sure that you have a 2-stroke single or 4-stroke single, 360° parallel-twin, or in-line four. Don’t try simultaneously firing the plugs on a 2-stroke twin! Also, some Japanese 4-stroke parallel-twins (especially the 250s) use a 180° crankshaft. When one piston is at the end of its compression stroke, the other piston is at the end of its inlet stroke. No prizes for guessing what happens when you fire a “spare” spark through that cylinder full of air/ fuel mixture! Similar problems may arise if you fire both plugs simultaneously on to above does not lead to a reliable system and since the points are the weakest part of the Kettering system I would strongly recommend that if your readers elect to build an elec­ tronic ignition system then only the breakerless system should also be used. (R. B., Kalamunda, WA). •  The nominal wetting current in our original HEI design is around 250mA which should be sufficient to ensure reliable opera­tion. Indeed, several of our own staff have run points/TAI sys­tems in cars for many years without points fouling. Even so, points do present problems with variable timing, bounce and in particular, rubbing block wear. If the points gap is not regularly adjusted to compensate for rubbing block wear, the system will eventually come to a complete halt. By comparison, any breakerless system is a dream. It never needs adjustment, the engine runs more smoothly and dirt is never a problem. We can see no reason to persist with points. “V-twin” or horizontally-opposed engines. Do your homework and make sure you know what’s going on in each cylinder before firing both plugs together. (D. J., Mulgrave, Vic). Notes & Errata 12V Trickle Charger, October 1998: the circuit on page 75 shows the transformer with two 15V windings connected in parallel but there is only one winding connected to the bridge rectifier. The wiring diagram on page 77 is correct. 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. November 1998  93 MARKET CENTRE Cash in your surplus gear. Advertise it here in Silicon Chip. FOR SALE SPEAKERWORKS: specialist in speaker repairs and par ts. DIY refoam kits: 3 1/2 ", 4", 5", 6", 7", 8", 9", 10", 11", 12" and 15" $39.95. Includes shims, dustcaps and adhesive. Largest inventory of cones, surrounds, gaskets, spiders, dustcaps, grilles, foam and cloth and 4,700 custom voice coils. Phone 02 9420 8121, Fax 9420 8131. ELECTRONIC ENGINEERING SERVICES: digital & analog, embedded & Windows/PC based designs, complete solutions or design advice/assistance. Phone 03 9807 9886. Email caddy<at>netspace.net.au 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 TELEPHONE EXCHANGE SIMULATOR, SC February 1998. Test all sorts of equipment without the cost of extra telephone lines. Melbourne 9806 0110. WEATHER STATIONS: Windspeed & direction, inside temperature, outside temperature & windchill. Records highs & lows with time and date as they occur. $399.00 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., 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. LASER SHOW SYSTEMS: complete blue Argon laser with pre-programmed patterns enclosed in metal road case $1500. Phone Ian (02) 9452 4302. CLASSIFIED ADVERTISING RATES Advertising rates for this page: Classified ads: $10.00 for up to 12 words plus 50 cents for each additional word. Display ads (casual rate): $25 per column centimetre (Max. 10cm). Closing date: five weeks prior to month of sale. To run your classified ad, print it clearly 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. 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 VIDEO SURVEILLANCE CAMERAS & EQUIPMENT. SPECIALS: CAR ALARM - REMOTE CONTROL - LOCK CONTROL - IMMOBILISER only $99! 380 + Line x 0.2 Lux SILICON MODULE only $59! DOME HOUSINGS only $5! 50 LED DIY Infra-red Illuminators only $19! MODULES: AWFUL-CMOS $49! PREMIUM 400 + Line x 0.05 Lux SONY H.A.D. CCD & CHIPSET from $91. CAMERAS: Mini 36 x 36 from $88. Dome from $91. DIGITAL COLOUR CAMERAS & MODULES: 400 + Line from $180! DOME from $185! 600 + Line from $346! 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AMATEUR, CB RADIO & other Consumer Electronics Trading Centre can be found at www.mackay.net.au/~ajl 1A LASER DIODE Driver, 3W head laser power monitor, IR laser diode with housing, greatly reduced price, e-mail lmatthee<at>perthpcug.org.au for details and pictures. RAIN BRAIN AND DIGI-TEMP KITS. Also 60 channel Moni-temp with alarms and PC Data logging. Mantis Micro Products, 38 Garnet Street, Niddrie, 3042. (03) 9331 4786. Fax (03) 9331 4782 http://www.home.aone.net.au/mantismp SATELLITE RECEIVERS * LATHES. 500 Ch STEREO ANALOG 64 BIRD POSI­TIONER! 200 Ch DIGITAL DVB MPEG-2! Specials-be-Quick! Analog w/64 Bird Memory, Az/El Power supply & Outputs, 128 Step Polariser Cont, 2 LNB Inputs, 12V 14/18V & 22kHz Switching, everything in one unit $399! DIGITAL with Automatic Viterbi Selection, 12V, 14/18V, 22kHz & DigiSeq LNBF-Control & RF LoopThru, Scart/RCA S-VHS Outputs, On-Screen Dish Positioning Menu & Signal Strength Meter $499! METAL TURNING LATHES Compact yet Fully Featured, Forward/Reverse Power Feed, Cross & Compound Tool Holder, TEN Pitch 0.04 to 2mm Thread Cutting Gear Set, 400W Variable 460-2500 RPM Motor, 180mm Swing, 250mm BC, Completely Self-Contained - 32kg use it on a Bench - store it in a Cupboard. $1199! Allthings Sales & Services 08 9349 9413 Fax 08 9344 5905. HOMEBUILT DYNAMO, engineering dreams into reality. “An absolutely marvellous book for the true ex­ perimentalist!” Elektor Electronics. (www.onekw.co.nz) C COMPILERS: everything you need to develop C and ASM software for 68HC08, 6809, 68HC11, 68HC12, 68HC16, 8051/52, 8080/85, 8086 or 8096: $145.00 each. Macro Cross Assemblers and Disassemblers for above CPUs + 6800/01/03/05, 6502 and 68HC12 now combined at the new low price of $75. Debug monitors: $75 for 6 CPUs. All compilers, XASMs and monitors: $480. 8051/52 Simulator (fast, now incl. 80C320): $75. 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 and 89Sxx series, and the new AVRs in both DIP and PLCC44. Also does most 8-pin Positions At Jaycar 651 Forest Rd, Bexley 2207 makes all the project PCBs published in SILICON CHIP and other Australian magazines Tel +61 2 9587 3491 Fax 9587 5385 http://www.cia.com.au/rcsradio/ 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 Need prototype PC boards? 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 PIC84/12 PROGRAMMERS: Many models available. Also other PIC-driven devices. EST (02) 9789 3616 or www. internetezy.com/au/~sesame 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. 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. GRAN­ TRONICS PTY LTD, PO Box 275, Wentworthville 2145. Ph (02) 9896 7150 or Internet: http://www.grantronics.com.au RTN Australia Parallax distributor: Basic Stamps, SXKey develop­ ment tools and SX chips. Wireless RF modules, serial LCD modules, Basic Stamp Bug, etc, etc. FerretTronics >R/C servo control chips. NEW: HandyScope 2 from Europe, 2 channel/12 bit portable measur­ i ng instrument, it’s a voltmeter, digital storage CRO, transient recorder and spectrum analyser. All in a very small box powered off a parallel port. DOS and Windows software provided. Ph/ Fax (03) 9338-3306. email: nollet<at>mail.enternet.com.au http://people.enternet.com.au/~nollet LOGIC ANALYSER 100Ms/s 32-Channel Kit $1275. Stand alone, not a plug in PC Card. Requires a VGA or EGA monitor - user supplied. Edge and Level Triggering. Multiple Triggering Modes such as, Trigger on pulse width too long or too short, Clock Stop, User Defined Storing, 2 Level Sequencer. Request brochure from: Peter Baxter, Tantau Australia, PO Box 1232, Lane Cove 1595, Sydney. Ph: 02 9878 4715 Fax: 02 9888 7679 Email: peter.baxter<at>tantau.com.au. All manuals on the website: www.tantau.com.au. Revised, no prototype area, “8051 Proto-Board” EA Feb 93. $30. A NEW address for Acetronics http://www.acetronics.com.au On-line PCB quotes, free software, DIY PCB supplies plus many other items & services. 02 9743 9235. KIT ASSEMBLY ANY KITS assembled/calibrated: professional, speedy service. Phone Nev­ille Walker (07) 3857 2752. KITS ASSEMBLED: Cheap & reliable service. Phone Erik (03) 5442 2163. WANTED TECHNICS TWEETER EAS-6PH13S; Tuner for Palsonic VCR-500D; Sharp IC X0077GE. Phone (02) 4954 6636. November 1998  95 14 Model Railway Projects Shop soiled but HA LF PRICE! Our stocks of this book are now limited. All we have left are newsagents’ returns which means that they may be slightly shop soiled or have minor cover blemishes. Otherwise, they're undamaged and in good condition. SPECIAL CLEARANCE PRICE: $3.95 + $3 P&P (Aust. & NZ) This book will not be reprinted Yes! Please send me _____ copies of 14 Model Railway Projects at the special price of $A3.95 + $A3 p&p (p&p outside Aust. & NZ $A6). Enclosed is my cheque/money order for $­A__________ or please debit my Advertising Index Altronics................................. 60-62 Aust. Audio Consultants...............91 Dick Smith Electronics..................... ................................ IFC,OBC,14-17 Harbuch Electronics....................92 Instant PCBs................................95 Jaycar .............................. 45-52,95 Kits-R-Us.....................................95 Microgram Computers...................3 Norbiton Systems........................22 Oatley Electronics........................35 Printed Electronics.......................95 Procon Technology......................95 Quest Electronics........................57 RCS Radio...................................95 Resurrection Radio......................80  Bankcard     Visa Card    MasterCard Card No. Rocom Electronics.......................23 Scan Audio..................................21 Signature­­­­­­­­­­­­___________________________  Card expiry date______/______ Silicon Chip Bookshop.................13 Name Silicon Chip Subscriptions...........44 ______________________________________________________ PLEASE PRINT Street ______________________________________________________ Silicon Chip Binders/Wallchart....43 Suburb/town_________________________________ Postcode_________ Smart Fastchargers.....................57 Send your order to: SILICON CHIP, PO Box 139, Collaroy, NSW 2097; or fax your order to (02) 9979 6503; or ring (02) 9979 5644 and quote your credit card number (Bankcard, Visa Card or MasterCard). Solar Flair/Ecowatch....................94 Solis.............................................96 Taig Machinery............................92 Truscott’s Electronic World...........21 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 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”