Are you a Do-It-Yourselfer? Hone your soldering techniques on Elencos Sound Activated Switch Soldering Kit. Just clap your hands together twice and watch the Sound Activated Switch turn on the light emitting diode (LED). Clap twice more and watch the LED turn off. A one-shot, or monostable multivibrator, is a circuit that, once triggered, will switch its output logic level. The output will remain at this new logic level for a predetermined period of time, after which the output will switch back to its previous logic state. This is the core of the Sound Activated Switch. From the company that brings you Snap Circuits - 9 volt battery not included. - MADE IN THE USA - Elenco was founded more than 30 years ago by 2 engineers. The core of Elenco is still strong engineering and design skills. Elenco test equipment has proven to be reliable as well as affordable. Elenco supplies Universities and High Schools with quality educational kits and materials.