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Adding a wireless remote control to the by Ross Tester BARKING DOG T here’s a couple of pooches next door that really do have me barking mad. They start yapping at the drop of a hat and to make matters worse, their idiot owner howls and woofs at them . . . which of course sets them off even more. So when John Clarke came up with his new Barking Dog Blaster last month, I couldn’t wait to try it out! And guess what? It seems to work! Of course, nothing stops them when stupid is goading them. But at other times, if they start barking and I can race over and hit the “start” button quickly enough, more often than not they cease with the racket and look around to see where that infernal noise (to them!) is coming from. Mr Pavlov, you might just have been on the right track! Well, so far so good. But (isn’t there always a but?) the delay in getting up, going across to the start button and pushing it quite often meant that the barking had ceased of its own accord. This started me thinking, what if it could be triggered automatically – for example, put a microphone and amplifier in it so then when it sensed a bark, it fought back. 84  Silicon Chip However, when I discussed this with John he told me he was one step ahead of me – in fact, earlier versions of this device used exactly that idea. The downside was that any loud noise would trigger it – neighbourhood kids, traffic, low-flying aircraft, thunder, you name it – and the at-the-timenon-barking dog in question would be somewhat confused by the screech from the speakers – was it directed at him or wasn’t it? Scratch that idea. OK, if we couldn’t have it automatic, what about reducing the time between bark and blast, some sort of remote switch, which could be kept within easy reach, ready to hit on the first bark? This idea had merit – so much so that we actually promised it at the end of the article in September (boy is that dangerous!). But in this case we figured it couldn’t be too hard – and so it proved. Which remote switch? The wireless switch simply replaces the push-button switch of the original article. Or, if you wish, can be wired in parallel with that switch. One will not affect the other. The choice is basically between an infrared remote switch or a wireless (radio) remote switch. We’ve described numerous versions of both in SILICON CHIP. We weren’t The UHF remote switch from our January 2009 issue with the receiver on the left and transmitter on the right. While still practical (and available from Jaycar as a kit), for this project it’s perhaps too clever. siliconchip.com.au Fitting a second PCB to the original case proved impossible, so we went for a larger (UB1) case and mounted the receiver PCB on the end wall. The other modification we made was to fit a 6.35mm mono jack socket so we could separate the piezo tweeter box more easily. after a lot of range – ten metres or so should be ample – but we were after more than line-of-sight. So that pretty-much ruled out infrared – they don’t work around corners too well! We then went back to radio-based wireless remote controls and found several to choose from. The most recent was one described in the January 2009 issue – a 433MHz UHF Remote Switch (again from the fertile brain of John Clarke). It looked like it would do the job – in fact, it certainly would – and we even went to the extent of arranging a kit from Jaycar Electronics. But on closer examination, this de- sign was simply too good for the task. It had more features than was required for a task as simple as this. Was there a simpler route? Then we recalled an advert from Kitstop in the August 2012 issue (page 6), featuring a small, simple 433MHz keychain transmitter and matching receiver, already built and tested, for less than $30.00. While it had two channels (we only needed one) it otherwise appeared to be exactly what we wanted so we obtained a set from Kitstop (www. kitstop.com.au; cat no KSRC2) – and this article is the outcome. Of course, if you want the thrill of building your own remote switch The alternative KSRC2 transmitter/receiver pair from Kitstop (www.kitstop. com.au). It’s prebuilt into the bargain – so you can’t go wrong! siliconchip.com.au there is nothing to stop you doing so (Jaycar Cat No KC5473). Indeed, the case we’ve chosen will (just!) fit the January ’09 receiver PCB in the end (in the same position as the Kitstop receiver shown in the photo above). Identify the terminals If you’re using the Kitstop module, there are two things you need to confirm – first that the transmitter is set up to talk to the receiver and second, which terminals to use. Because both transmitter and receiver are pre-assembled and tested, it’s almost certain that the first will be OK as supplied. But just in case, (eg, if you have reason to change coding because of interference) Kitstop include details of how to change the coding on both transmitter and receiver. As far as the terminals are concerned, normally, button “A” on the transmitter fires the receiver’s “1” relay contacts. It holds the relay in while ever the button is pressed – exactly what we are after. Before putting the receiver module October 2012  85 12V DC IN CON2 NC1 COM NO1 NC2 COM NO2 C 2012 2200F 16V LOW ESR F1 2A CON1 S2 START SWITCH (IF USED) 10 VR1 10k LED1 2X STP30NE06L BARKING GOD GNIKDOG RAB RBLASTER ETSALB 125108121 2180152 T1 CON3 S3 S2 SPEAKER OUTPUT F1 F3 5.1V 1k 10 10k 560 IC1 PIC12F675 10k A 10F S1 F2 5.1V 100nF 100nF UHF REMOTE SWITCH PCB MOUNTED VERTICALLY ON END OF BOX ZD2 Q2 2.2k START 10 +12V OUT 0V LP2950ACZ-5.0 REG1 10F 10F 4004 D1 1k POWER SWITCH RELAY 2 ACTUATED BY BUTTON B ON TRANSMITTER +12V 0V RELAY 1 ACTUATED BY BUTTON A ON TRANSMITTER 2200F 16V LOW ESR ZD1 Q1 ETD29 EXTEND LED LEADS BY ~15mm THESE WIRES ONLY NEEDED IF START SWITCH IS USED (IN PARALLEL) (POLARITY UNIMPORTANT) TO PIEZO TWEETERS There’s no circuit diagram (it’s in last month’s issue) – simply add the receiver module as shown here. We’ve shown the Kitstop KSRC2 module; using the January 2009 design is similarly mounted (albeit a tighter fit). We’ve “opened out” this diagram for simplicity – the receiver module actually mounts vertically on the end wall of the UB1 box, with the 6.35mm socket on the opposite end wall, as shown overleaf. The larger front panel can be downloaded from siliconchip.com.au. in the box, connect it to 12V and press a transmitter button – each button should make its associated relay pull in (you’ll hear the click). The Barking Dog Blaster is switched by the “NO” and “COM” contacts – you might like to confirm with a multimeter that they are only closed when the button is pressed. Putting it together With the extra PCB (whether it’s the Kitstop prebuilt or the Jaycar kit) the project will not fit inside the original (UB3) case. So we went up to the UB1 case – it’s 158 x 95 x 53mm so there is tons of space within the case, as you can see from the photo. A new, larger, front panel label was also prepared. The start switch was originally wired to the bottom two terminals on CON2 (they’re labelled “start”) while 12V power for the receiver PCB is available the next two terminals up (thoughtfully labelled +12V and 0V out). As the Kitstop receiver PCB has a standby current of 13mA, you might want to fit a power switch to the top pair of terminals, especially if you are running the unit from a 12V battery. In this case, the link between the top two terminals would be removed 86  Silicon Chip and replaced by wires to the power switch. That switch could be accommodated anywhere convenient on the front panel. The other modification we made to the original circuit was to connect a 6.35mm mono jack socket to the transformer output (CON1). This was done simply for convenience – it’s so much easier to be able to disconnect the driver unit from the speaker array. Position is unimportant, as long as it clears the components on the PCB and also allows the lid to be fixed in place. Naturally, this also required fitting a 6.35mm mono jack plug to the speaker wires! PCB location is not overly critical but it makes sense to keep the receiver PCB away from the transformer. We used the PCB itself as a template to drill the four holes for its mounting screws, placed the PCB in position in the case then carefully marked the horizontal position of the hole for the 12V DC input plug. The vertical position for this hole was 38mm down from the top of the case (ie, without lid). It’s easier to measure down from the top as you have a definite edge to measure from. One minor problem is LED height – in the deeper box, even soldered with as much lead as possible, the LED top is still about 15mm or so below the panel, so you need to mount the LED on a pair of 15mm long wires. In fact, you might find it easier to mount the LED in a bezel on the lid and use flying leads (eg a pair of wires from rainbow cable) to connect to the PCB. Wiring Wiring the rest of the project is quite simple – just follow the diagram. It’s difficult (if not impossible) to connect your wiring to the receiver PCB terminals with it mounted in place (the terminals are horizontal and difficult to access), so you will need to connect its wiring first. Wiring to the Blaster PCB is easy because the terminal screws all face to the top. Once completed, attach four small self-adhesive feet to the underside of the box to prevent the screw-heads scratching any surface the unit is placed on. In the absence of rubber feet, four dobs of silicone sealant a little higher than screw-head height will do. You’ll find complete setup and troubleshooting details in last month’s article so we won’t go over old ground here. Just remember, anything that the pushbutton switch referred to in that article will do, the remote switch will SC also do. siliconchip.com.au