Sound sensor circuit diagrams

Voice Operated Switch

This circuit is a voice operated switch (VOX) and designed for audio frequencies within a commercial telephone bandwidth of 100Hz to 3000Hz. Input amplitude is sensitive down to 10mV and the output comparator can drive a relay or interface to micro processors and TTL switching between 0 and 5Vdc.

Clap Relay

Clap sensitive on-off Relay. 3V Battery operated, small portable unit

Whistle Responder

Beeps when hears your whistle. A gadget suitable for key-holders, games etc.

Sound Operated Switch

A sound operated switch with a relay driver.

Audio Perimeter Monitor

This circuit is intended for audio surveillance of an unattended area, examples being a back garden or open space. It can be used to listen for wildlife or just as an extra pair of ears.

Room Noise Detector

One LED monitors three levels: 50, 70 & 85 dB Useful to detect too noisy environments

Electronic Candle Blow Out

LED or bulb switch off with a puff. Funny gadget - 3V Battery supply.