Nuts and Volts - September 2013

With the Sonic Sensor taking care of providing a gate or rising edge to fire a CMOS flip-flop or counter, the sky is the limit on what you can come up with.

For the most versatile approach possible, consider connecting it up to a microcontroller. The firmware can then do all sorts of things like count pulses, take averages, monitor intervals between bursts, check the clock times the sounds occur, route the results to buzzers, relays, motors … you name it.

Just as one offhand example, suppose you own a summer cabin but don’t expect to be there for several months. You could come up with a circuit that turns on floodlights whenever any crashing sound is heard (breaking glass, forced entry through a door, etc.).

Back to handclaps. I’ve provided two PIC12F683 programs written in the free and open-source Great Cow Basic language that are really pretty interesting; get them at the download link for this article. The first simply bumps a counter for each clap of the hands, showing the current count on some LEDs in binary.

The second program is even fancier and will start counting as soon as you start clapping, then stop the count when you stop. With this, you could control a large number of devices. For example, clap once and a lamp turns on. Clap twice and it turns off. Clap three times and the radio turns on; clap four times and it turns off again. You can keep going like this almost indefinitely (limited only by the port pins of your microcontroller).

Unlike those commercial units of yesteryear, you now have the ability to put a large number of appliances under sonic control. The sample programs are heavily commented and also give any hookup instructions to the LEDs and so forth. Note too that the programs utilize one of the PIC timers in case you’ve ever wanted to learn more about them.

When testing my unit, I found I could get it to reliably count handclaps at a distance of up to 30 feet with the sensitivity set on max. Plus, it shouldn’t really be any great hurdle to port the sample programs over to an Arduino should that be your weapon of choice.

One final thing before I turn you loose to whip up you own applications. Controlling AC devices like lamps, radios, televisions, etc., is serious business. So, be safe! Use properly implemented opto-couplers and relays to isolate the Sonic Sensor from any 110 VAC apparatus.