# How the Clapper Works

## Mechanics of the Clapper

The inner workings of the Clapper
2010 HowStuffWorks.com

Electronically speaking, the Clapper is not that complicated. Sound-activated toys have existed as far back as the 1950s. However, the brilliance of the Clapper is that it's able to distinguish between different sounds -- and it does so with only a few dollars worth of electronics. Crack open a standard Clapper, and you'll see little more than a microphone, an electronic sound filter and two electrical switches.

The microphone, mounted at the front of the device, is always tuned in to the surrounding environment. Every sound that hits the Clapper is "heard" by the microphone, turned into an electrical signal and sent to the electronic sound filter.

The filter's job is to determine which of the sounds being sent to it by the microphone are claps. It does this only by recognizing sounds that fall within a certain frequency range (hand claps are typically within the 2200 to 2800 hertz range) and ignoring everything else.

Every time the filter registers a "clap," it sends a signal to one of two electrical switches -- each of which activate a separate electrical outlets on the exterior of the device, which is where you've plugged in your TV, radio or lamp. The switches are each cued to only turn on if they receive a certain number of signals from the filter. Two signals will set off the first switch, and three signals will set off the second switch.

By clapping, you trigger the microphone to set off the sound filter, which in turn sends a signal to the electrical switches. Clap twice, and two signals are generated, setting off the first outlet. Clap three times, and three signals are generated, setting off the second outlet.

To turn off an outlet, simply repeat the process. When one of the electrical switches is on and it receives the appropriate sequence of signals from the filter, it'll simply switch off.

Keep reading to find out how what a Clapper and a Doberman have in common.