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'I'HE B WOOFER STOPPER! Do you have a noise pollution problem of the canine type? If so, then don't take "woof' for an answer - zap it with the Woofer Stopper! By DARREN YATES Let's face it - there are fewer things in life more annoying than a dog barking at 4 o'clock in the morning. It doesn't matter what your problem is, it is seemingly insignificant when stacked against a flea-bitten mutt with the urge to howl in the wee-hours! It's also quite amazing how many owners disregard the noise their dogs make and the discomfort they cause other people. So much so, that barking dogs are a common source of friction between neighbours in urban areas. 26 SILICON CHIP However, there are several plans of attack for the frustrated neighbour. These involve exploding cans of dog food, armed combat with the offending mutt, and forcing it to watch endless re-runs of"Benji". Others are less savoury and we cannot mention them here but none are as elegant as our Woofer Stopper! We have had many requests for a dog zapper that really works - nothing to injure the animal mind; just something to act as a reprimand and make the dog shut up. The Woofer Stopper is the result of our endeavours. At the press of a button, it emits a retaliatory high-level supersonic tone that lasts for about nine minutes. Because this tone has a frequency of about 20kHz, it's beyond the range of human hearing but is well within the hearing range of a dog. The idea behind the device is that it packs a big enough aural punch to chastise the dog and knock the bark out of it. Basically, it's the high-tech equivalent of the good old fashioned but often ineffective "shaddup-yer-barking" bellow out the window. What's more, if the device is used on a regular basis, the animal eventually realises that it is going to be reprimanded if it barks and eventually ceases to be a problem. But the real beauty of the device is that your inconsiderate neighbour doesn't even know that you're getting your own back on his equally inconsiderate mutt. And of course, you can get back t5V tV1 16 16 11 10M 10 04A 2.2k 1k G D IC5a O 3 4013 - 2 C 0 s R 8, 9 7 7 12 3 7 06 MTP3055A G 10 IC2 4518 ENB 14 048 IC1 74HC4060 04 MTP3055A 14 7 7 7 33pFI 33pf+ tV1 t5V START S1 I 0.1+ 08 MTP3055A D G 14 16 i~i4 03 1 10 CK IC3 0 14 3 CK 4020 .015Hz R R 11 8 s 100 k IC5b 7 0 ,2 0 0 E I G0 C VIEW ED FROM BELOW 7 GDS 7 ';' D1 1N4004 D6 1N4148 0.1 6 ~ B 244.1Hz +sv---1 12VDC 300mA PLUGPACK I 100k S2 +5 V ·+ 1000 + 220n 16VWi 10 + D2 1N4004 16VW+ 7 7 + 7 'T' 81 I 12V I ...L.. WOOFER STOPPER Fig.i: the circuit uses IC1 & crystal Xl to generate a 4MHz timing signal which is divided down to 20kHz by IC2 & IC5a. IC5a provides complementary square wave outputs & these drive transistors Ql & Q2 which in turn drive an H-pack output stage consisting of Q4-Q7. IC3, IC4 & IC5b form the 9-minute timer. to sleep while the dog it still in the process of being zapped. Who was it that said "every dog has his day"? And now for the $64,000 question . Does it work? Well, from our own limited trials the answer is a resounding yes but we cannot guarantee that it will work with every dog. There are several reasons for this. First, some dogs are just plain stupid and that's all there is to it. Second, many older dogs are deaf and so wouldn't realise that they were being zapped by the Woofer Stopper, although older dogs are generally not problem barkers. And third, the range of the device is fairly limited which means that the dog has to be no more than about two doors away. A range of about 20 metres has been proven in practice but we haven't really had an opportunity to check the effectiveness of the device over longer distances. It certainly wouldn't stop a dog that's barking at the other end of the street. Circuit details Initially, we h ad ideas of a soundoperated mechanical arm that dropped half a hou se brick on the dog's head. However, most of the SILICON CHIP staff are dog lovers and insisted that this idea be scrapped in favour of an entirely electronic approach. Refer now to Fig.1 for the circuit details. We'll go through each circuit section step-by-step and explain how it all works. Timing for the circuit is provided by ICl, a 74HC4060 high-speed CMOS 14-bit counter and oscillator whose frequency is set by a 4MHz crystal. The reason for using the "HC" version of the 4060 is that a standard CMOS type cann ot be expected to run reliably at 4MHz with only a 5V supply. The two 33pF capacitors provide the correct loading for the crystal so -+ that it always starts reliably when power is applied to the circuit. The output from ICl is taken from pin 9, which is the direct 4MHz output from the oscillator. This is fed into IC2, a 4518 dual BCD counter configured as a divide-by-100 circuit. The resulting output at pin 14 (Q4B) is a pulse waveform with a frequency of 40kHz. From there, the signal is fed into D flipflop IC5a which divides by two . This not only divides the signal down to the 20kHz we want but also provides 50% duty cycle complementary square wave outputs at pins 1 and 2. Mosfets Q4-Q7 form an H-pack output stage in which diagonally opposite devices alternately conduct together, with the output device (a piezoelectric tweeter) forming th e bridge in the middle. Each Mosfet is an N-channel device which means that it turns on when its gate voltage is higher than its source voltage. The complementary signals from IC5a appear at pins 1 and 2 and drive transistors Ql and Q2 respectively via 22kQ resistors. These two transisMAY 1993 27 S2 SPEAKER SOCKET ing signals for the H-pack output stage, ICl also forms part of the delay timer circuitry. Its pin 3 output delivers a 244Hz square-wave signal (ie, the 4MHz clock signal divided by 214 ) and this is then fed to IC3. IC3 is a 4020 14-stage binary counter and is used to divide the 244Hz signal on its CLK input (pin 10) by a further 214 . The resulting signal is then divided by eight by 7-stage binary counter IC4 to produce a waveform which goes low for 536 seconds (ie, slightly less than nine minutes) . During this time, Q3 will be off and so QB turns on to enable the H-pack output stage (Q4-Q7). Reset circuit * SEE TEXT Fig.2: install the parts on the PC board & complete the wiring as shown here. Note the three vacant pads between ICl & Xl. To test the circuit, link the middle & bottom pads so that the tweeter delivers a ZkHz tone. When testing is complete, remove this link & link the middle & top pads instead. tors then provide the necessary drive current for the H-pack output stage. The H-pack output stage in turn is switched on and off by Q8 which forms part of the timer circuit. For example, let's assume that Ql is on (ie, pin 1 of IC5a is high) and that Q2 is off. Assuming that Q8 is also on, this means that Q4 and Q7 will be on and so current flows from the supply rail, through Q4, through the piezo tweeter, through Q7 and then through Q8 to ground. When the outputs of IC5a toggle, Q4 & Q7 turn off and Q6 & Q5 now switch on. Current now flows from the supply rail through Q6, through the tweeter in the opposite direction to before, and then through Q5 and QS to the ground rail. Because both ends of the tweeter are alternately switched between the positive supply rail and ground, we actually get twice the supply voltage developed across the tweeter. This ensures that the tweeter delivers adequate punch (the power is almost quadrupled), despite the limited supply voltage. As well as providing the initial tim- Flipflop IC5b performs several roles in the circuit. First, it ensures that IC3 and IC4 are correctly reset when power is first applied and at the end of each timing cycle. Second, it releases the reset lines on IC3 and IC4 and allows them to count when the START button (Sl) is pressed. And third, it turns Q3 on outside the timing period to disable the H-pack output circuit. When power is first applied, pin 10 (reset) of IC5b is momentarily pulled high via a 0. lµF capacitor and diode D3. This resets IC5b and so its Q-bar output (pin 12) goes high and also resets IC3 and IC4. At the same time, it turns on Q3 via D5 and thus Q8 is off and the siren driver circuit (ie, the H-pack output stage) is disabled. When the START button (Sl) is subsequently pressed, IC5b's set input is momentarily pulled high and so its Q-bar output switches low. This turns Q3 off and so Q8 now turns on to enable the siren diver circuit. IC3 and IC4 now begin counting up in response to clock signals from ICl. After about nine minutes, pin 6 of IC4 switches high and turns on Q3 via D6 to switch the siren off again. This high also resets IC5b via D4 which means that Q-bar of IC5b switches high again and resets IC3 & IC4, ready RESISTOR COLOUR CODE 0 0 0 0 0 0 28 No. 1 3 3 3 1 SILICON CHIP Value 4-Band Code (1%) 5-Band Code (1%) 10M.Q 100k.Q 22k.Q 1k!:! 220.Q brown black blue brown brown black yellow brown red red orange brown brown black red brown red red brown brown brown black black green brown brown black black orange brown red red black red brown brown black black brown brown red red black black brown ~ ., ... ,.,v:, . ., , . PARTS LIST ~ ~- '. ~ . ~ v",. ~ 1 PC board , code 03105931, 123 x 82mm 1 plastic zippy case, 198 x 113 x 62mm 1 momentary pushbutton switch (S1) 1 SPST toggle switch (S2) 1 black banana socket (optional) 1 red banana socket (optional) 1 2.5mm DC socket 1 3.5mm mono socket 1 12VDC 300mA plugpack 1 piezo tweeter (Jaycar Cat. CT1907, DSE Cat. C-2005) 1 4MHz crystal Semiconductors The PC board is secured to the lid of the case· using machine screws & nuts, with additional nuts used as spacers. Make sure that all polarised components are correctly oriented. for the next timing cycle. The high on Q-bar of IC5b also now holds on Q3 (via D5) and thus the siren is disabled until the START button is pressed again, whereupon the cycle repeats itself. Power for the circuit is derived from a 12VDC plugpack supply, with optional back-up provided by a 12V rechargeable battery (either nicad or SLA). As shown in Fig, 1, the incoming DC from the plugpack is fed via reverse polarity protection diode Dl and switch S2 to a 3-terminal 5V regulator. The output from the regulator is then used to power the ICs, while the siren driver circuit is powered from the 12V supply on the input side of the regulator. Construction The Woofer Stopper is built onto a PC board measuring 123 x 82mm and coded 03105931. Fig.2 shows the wiring details. Before installing any of the parts, check the PC board carefully for etching defects by comparing it with the published pattern. Usually, there will be no problems here but it's always best to make sure. Assuming everything is OK, begin the board assembly by installing the 12 wire links (don't forget the link between the gates of Q5 & Q6). The resistors and capacitors can then be installed on the board, followed by the diodes, ICs and transistors in that order. Make sure that all polarised parts are correctly oriented and be sure to use the correct part at each location. In particular, note that diodes Dl & DZ are 1N4004 types, while diodes D3-D6 are 1N4148s (or equivalent). The five Mosfets (Q4-Q8) are all installed with their metal tabs towards the back of the PC board, as viewed in Fig.2 (see Fig. l for the pin connection details). Push these devices down onto the board as far as they will comfortably go before soldering their leads. Finally, complete the board assembly by installing the 4MHz crystal (it can go in either way around). Testing The completed board assembly must now be tested to confirm that it is operating correctly. How do you test the circuit when you cannot hear its output? The answer is to modify the circuit slightly so that it produces a ZkHz tone instead of a 20kHz tone. The first step is temporarily con- 1 7 4HC40.60 14-bit counter & oscillator (IC1) 1 4518 dual BCD counter (IC2) 1 4020 14-bit binary counter (IC3) 1 4024 7-bit binary counter (IC4) 1 4013 dual D flipflop (IC5) . 1 78L05 5V 100mA regulator 3 BC548 NPN transistors (01-03) 5 MTP3055A or MTP3055E power Mosfets (04-08) 2 1N4004 silicon diodes (D1 ,02) 4 1 N4148, 1 N914 diodes (D3-D6) Capacitors 1 1000µF 16VW electrolytic 1 10µF 16VW electrolytic 2 0.1µF 63VW MKT polyester 2 33pF ceramic Resistors (0.25W, 1%) 1 10MQ 3 100kQ 3 22kQ 1 2.2kQ 3 1kQ 1 220Q Miscellaneous Hook-up wire, solder, screws, nuts & washers nect the START switch, DC input socket and the tweeter to their respective pads. This done, take a close look at the PC board and locate the three vacant pads between ICl and the 4MHz crystal. These pads are used as a crude switch, with the centre pad as the wiper. When the middle and top pads are bridged, the circuit produces a Z0kHz tone. When the middle and bottom pads are bridged, the circuit MAY 1993 29 ~ =ff#------,----- Fig.3: this full size artwork can be used as a drilling template for the two front panel switches. WOOFEB STO:PPEB produces a 2kHz tone (ie, the clock signal is now taken from pin 7 ofICl). To test the unit, link the middle and bottom pads, connect the plugpack supply and switch on. Now press the START button. You should immediately be greeted by a 2kHz tone from the tweeter. In fact, it's a good idea to cover the tweeter with a blanket before switching on to lessen the impact on your eardrums. The next step is to check the timing circuitry by confirming that the tweeter stops sounding after approximately !:'I~ I o-o !.!..o M (J\ in 0 M ~ 0 o-cfibo Fig.4: this is the full-size etching pattern for the PC board. 30 SILICON CHIP + START POWER nine minutes. If you cannot stand to have the tweeter blaring away for this period of time, switch off, disconnect it and connect your multimeter (set to the 20V range) to the collector of Q3. This done, switch on and press the START switch again. Q3's collector should immediately go high (ie, to +12V). It's then simply a matter of confirming that Q3's collector goes low again some nine minutes later to end the siren period. Once you've confirmed that everything is operating correctly, remove 0 C\. + the link to the bottom pad and link the middle and top pads instead. The circuit will now produce the desired 20kHz square-wave. The three unused pads near diodes Dl & D2 interface to an optional remote control receiver (to be described next month). Final assembly All that remains now is to install the board inside the specified plastic case. The PC board mounts on the lid of the case (which now becomes the base) and can be used as a template for marking out its own mounting holes. Secure the board to the lid using machine screws and nuts, with additional nuts used as spacers.. You will also have to drill holes in both ends the case to accept the power input sockets and the output socket, plus holes in the front panel for the two switches. A 2.5mm DC socket is used for the plugpack supply, banana sockets are used for the battery and a 3.5mm mono socket is used for the output to the tweeter. If you don't wish to use the optionaL back-up battery, just leave its terminals out of circuit and omit D2 and its parallel 220Q resistor. Finally, try to position the tweeter as close to the offending dog as possible, while keeping it (the tweeter that is) out of the weather. Probably the best location is under the eaves of your house. SC