Voice: Activated

This mini-VOX - voice operated relay - is based on a circuit published in Silicon Chip, 9/1994, p31.

Adjust the sensitivity of this circuit to control a Relay that can turn on whatever is connected to the contacts of the relay. Very practical circuit for a variety of projects. Turn on a light when your dog barks, or set of a siren when an intruder makes

Three relay-based electronic switching circuits that switch according to light levels.

Sound turns on the transmitter, which operates in the FM radio band. A neat way to catch a thief in another room or garage. The volume of sound needed to trigger the circuit is adjustable. The two stage transmitter has good range and the circuit powers do

This circuit will play a tune when light strikes a light dependent resistor, such as when a music box lid is opened.