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Remote controller for garage doors, Pt.2 Last month, we presented the full circuit details for this project which essentially consists of a receiver/decoder board plus a ready built transmitter. This month, we give the constructional details and discuss how it can be used in a practical installation. By BRANCO JUSTIC We left off last month with a short discussion on the transmitter circuit which was shown on page 20 of that issue. It is supplied readymade and operational but it needs one component change and it must be coded. The component to be changed is the resistor connected between pins 15 30 SILICON CHIP and 16 of ICl. Shown on the circuit last month as lMQ, it needs to be changed to 220kQ. We suggest you change it and do the transmitter coding at the same time, to avoid unnecessary work. Before proceeding to modify the transmitter though, it is better to per- haps leave it for the moment in its supplied condition. So let's proceed to the assembly of the receiver/decoder board. As shown in the photographs, the receiver board has five SPDT relays mounted on it and these are supplied with the kit. We suggest that they be mounted on the board first, before all the other circuit components. There is just one small but very important point though. Five diodes and two resistors mount under those relays, so you'd better bung them in as the first step otherwise you will be more than a little cheesed off later on. Consult the wiring diagram of Fig.4 and you will see that the five diodes in question mount right underneath the relay coils. The two lOQ 1 W resistors actually sit between relays TO BATTERY POSITIVE Fig.4: this diagram shows the component layout for the receiver/decoder board, as well as the external wiring. Note that a diode sits underneath each relay coil and should be installed before the relays are mounted. The same goes for the two 10Q 1 W resistors. RLA 1 and RLA2, and between RLA3 and RLA4. 24 V operation Another diversion, before we get too involved with the construction, concerns the supply rail. We assume that most constructors will want to use a standard 12V automotive wiper motor and gearbox as the motive power for their garage door opener. These motors are quite efficient but have loads of torque since they are geared down a long way. Another option is to use a 24 V truck or bus wiper motor. If so, you will want to run the circuit at 24V. That means the two aforementioned resistors will need to be 120Q 2W units. We'll have more to say about the power supply arrangements later; back to the board assembly. Next, install the five diodes and two resistors and solder them in place. Make sure that the diodes are soldered in the right way around. It is important that the relays be carefully soldered into circuit, otherwise they will not work. Why? Because their metal frame is actually connected to the moving switch contact. If the frame is not soldered prop- erly, the relay will, for all intents and purposes , be open circuit. For that reason , make sure that the mounting lugs on the relay fram es are clean and bright. If they're not, clean them up with a Scotchbrite scouring pad. Don't, whatever you do , use steel wool. It will inevitably leave stray strands on the relay which will probably cause a future short circuit. When the relay mounting lugs are clean and bright, tin them carefully with your soldering iron (making sure that you only give them the lightest touch of solder). That done, push them all the way into their respective board holes and solder them to the board's copper pattern. You can now begin installing the smaller components, starting with the wire links, diodes and resistors. Note that some of the resistors are mounted end-on, because space is a bit tight. Now put in the capacitors. There are quite a few electrolytics - make sure that they are all correctly polarised, as shown on Fig.4, before you solder them into place. The last components to be mounted are the transistors and diodes and naturally, it is vital that they too are installed the right way around. Sock- ets are optional for the !Cs; use them if you want to. Finally, we fitted a 350mm insulated antenna lead to the receiver. We coiled the lead as shown in the photograph to keep the installation neat but it should be left straight if you want maximum range. When the board is complete, go over it very carefully to check component placement and your soldering. Fix any mistakes now. Now is the time to change that lMQ Our prototype was installed in a large plastic case, with the 12V light fitting mounted on the front panel. Also mounted on the front panel is the pushbutton switch which provides manual UP/DOWN operation. APRIL 1991 31 cut the relevant tracks to the data pins for ICl. Note that A4, A9 and All should be open circuit when you are finished (for this example, anyway) . Now, on the receiver/decoder board, use your soldering iron and a little solder to bridge (ie , short out with solder) all the desired high or low connections for Al, A2, A3, A6, A7, A8, A10 and A12. One thing you must be sure to avoid and is that you don't have bridges from one of the IC pins to both HI and LO. If that happens, you short the HI rail (which is protected on the transmitter board by a 10kQ resistor) and the circuit won't work. On the receiver, the 7808 providing the +8V rail should protect itself but the circuit still won't work. Power check This interior view of the prototype shows the receiver/decoder board and some of the external wiring. The battery is in place but not yet connected or bolted down. Note the coiled antenna lead near the lefthand side of the case. resistor in the transmitter to 220kQ, as mentionend at the start. Unclip the transmitter case, disconnect the battery, desolder the lMQ resistor and solder in the 220kQ unit. Now for the coding. The important thing to note about the transmi_tter and receiver coding is that they must be absolutely the same. If even one of the coding bits is different, you can press that transmitter button till the battery runs out and the receiver will continue to sit there and do nothing.Make absolutely sure that the coding is correct. How to code This part is where you program the transmitter and receiver with your own unique code. You do it by connecting various pins on the transmitter encoder (ICl) and the receiver decoder (IC2) high, low or leaving them open circuit. Fig.5 shows the general concept. It shows the copper PC pattern underneath both these ICs. You can see the IC pads and the HI associated HI (+V) and LO (0V) ~ rails. c» A1 c» C> A2· On the transmitter, there are tiny c» c». A3 tracks tying each data pin to the C> A4 c» c» A5 HI and LO rails. You'll need to cut A12 C> A6 one or both of these tracks on each A11 C> A7 A10 C> 0 AB data pin, to perform the coding. A9 On the receiver/decoder board, each of the data pins is unconnected and you will have to deRECEIVER TRANSMITTER cide whether to bridge each of the Fig.5: these are portions of the copper pins HI, LO or leave them unconPC pattern underneath the transmitter nected. encoder (IC1) and the receiver Now we'll give you an example decoder (IC2). You must cut one or of how to do it. both of the bridging tracks on all the Suppose you decide to make the data pins for the transmitter (left) and transmitter coding as follows: Al, use your soldering iron to bridge the A3, A6 and A10 all high; A2, A7, data pins HI or LO on the receiver. A8 and Al2 all low; and all other The coding for the transmitter and lines open circuit. To do this, you receiver must be identical otherwise the radio link will not work. simply use your utility knife to 32 SILICON CHIP To check the receiver/decoder operation, you'll need either a 12V AC or DC plugpack; it does not matter which. When power is applied to the receiver PC board, the light relay (RLA5) and the "Down" relays (RLA3 & RLA4) should operate. After about 2 minutes, the light relay RLA5 should drop out but RLA3 and RLA4 should remain latched. If the manual pushbutton is now pressed, the light relay RLA5 should once again operate, relays RLA3 and RLA4 should drop out, and the "Up" relays RLA1 and RLA2 should operate. To drop out the "Up" and the "Down" relays, you will have to operate the upper and lower limit switches respectively. Alignment The alignment procedure is quite simple since the transmitter is already aligned to 304MHz. You will need to make up the test circuit shown in Fig.6 . Connect it to test point TP1 on the receiver/decoder board. Press the .0033 TO TP1 - - - I I I - ~ . . - - - - - - , D1 OA90 GND1i------' .,. Fig.6: this little RF detector circuit is connected to test point TPl on the receiver board for the alignment procedure. You simply press the transmitter button & adjust CVl on the receiver for a maximum reading. HEAVY DUTY TV/SPEAKER WALL-CEILING BRACKETS The M83 and MB5 are heavy duty two platform mounting brackets designed for securing small TV's and speakers to walls, ceilings, desks or bench tops. When mounted both units can ~~'U7l ~~14l as well as being swivelled up or down to any viewing or listening angle. The metal platforms have predrilled holes tor mounting and are easily adjusted with a large alien key supplied with the unit. Imported and distributed by: .ABISTI\ ELECTRONICS Available through the following retailers: David J Reid All Electronic Electronics. Components. 127 York Street. 118 Lonsdale St. Sydney. 2000. Melbourne. 3000. NSW. (02) 267-1385. Vic. (03) 662 3506. ~{;!; A VIDEO DUBBING/ ENHANCING SYSTEM THAT DOESN'T COST THE EARTH. • Enhances Video and Audio Signals. • Mono/Stereo Compatible. • Simple Operation. • Can be used with most Video Cameras. This photo shows the motor drive arrangements on a roller door. The upper limit switch can be clearly seen. transmitter button and adjust trimmer capacitor CVl for the maximum possible DC voltage reading on your analog multimeter. As a point of interest, the prototype gave a range of over 200 metres with the antenna wire attached. Our prototype was installed in a large plastic case with a clear plastic lens on the top for the 12V garage light, switched by relay RLA5. Power supply details Inside the case is a standard multi- tap transformer (Altronics M-6672) with the 12V windings connected to the rectifier inputs on the board. Also installed is a 12V 6.5A/h sealed lead acid battery. This is connected as shown in the wiring diagram ofFig.4. This is trickle charged via an 82Q 1W resistor and it delivers power to the circuit and to the motor via a 1N5404 silicon rectifier diode. By using this power arrangement, the circuit will work all the time regardless of whether mains power is present or not - you still want to get The AVE SSL is easily installed and provides excellent results . 11111 ALL THIS FOR $49.00 (Includes P & H). ---------- TO ORDER Please mail coupon to: I I SOUNDRING PTY. LTD. PO BOX 154, CAMMERAY NSW 2062 I I Please send me _ _(Qty) AVE SSL video I systems. I dubbing/enhancing My cheque/money order or credit card de· I I tails for$._ _ _ are enclosed. I Name._ _ _ _ _ _ _ _ _ I I Address._ _ _ _ _ _ _ _ _ _ I I Phone._ _ _ _ _ P/code I Tel: (02) 967 2411 Fax: (02) 958 7199 ~------------~ APRIL 1991 33 A typical motor drive arrangement for a Tiltador. A length of 1-inch water pipe serves as a carrier for the linkage for the door and it is driven back and forth by the bicycle chain. Here is a closeup view of the main drive gear on the roller door. This one has been welded but there is no reason why it could not have been attached with bolts and spacers to the inner frame of the door. This is a commercial installation on a panel lift door but the principle of operation is very much the same as the Tiltador example. The main spring is part of the original door mechanism. into your garage during a blackout. Using the battery also means that the transformer really only has to trickle charge the battery, not drive the motor directly. Installation details The actual installation will depend on your type of door. To give you a good idea of how it can be done, we'll let the photos included with this ar34 SILICON CHIP tide do the talking. All are based on chain drive using readily available bicycle sprockets. Some of the brackets used in the photos have been welded but there is no reason why you can't use all bolted construction or brackets made of timber, provided they are strong enough. Once you have your installation complete and working, you will need to ensure that the top and bottom limit switches do work as desired and that the over-current trip circuit is adjusted. To set the over-current adjustment, place an obstruction such as a cardboard carton underneath the door. Set the lower · limit adjustment VR2 so that the descending door does not crush the carton but does not tend to stall when starting. To set the upper limit adjustment, get someone to hang onto the door to give it some extra load. Again, set the adjustment (VRl) so that the door · does not stall when starting but will stop when given an extra load. Finally, note that there are a few changes to the receiver circuit which have been incorporated into the final PC board layout of Fig.4. First, the lkQ resistor connected to one end of choke RFCl is now 2.2kQ and extra bypassing components (a 4.7kQ resistor and lOµF capacitor) are now incorporated into the supply line for Ql. Second, pin 12 of ICla is connected directly to ground and the lOMQ resistor is deleted. And third, the pin numbers for IClc and ICld on the receiver circuit are actually swapped on the board layout. SC