Ldr: Light Activated

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

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

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

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

The Traffic Lights circuit performs actions just like those of a real traffic light system, switching between red, amber & green.

The most popular use for this kit is to make you own night-light. It can also be used to switch just about any appliance on or off in light or darkness. Light sensitivity is adjustable over quite a range. The relay can handle up to 10 Amps at 110VAC. Oper

Versatile light organ based on PIC microcontroller.

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

Introduces the Optocoupler-triac MOC3010. Complete electrical isolation between input audio signal (low voltage circuit) and output light modulation. Operates from 100 VAC line. Audio input via 3.5mm jack.

A sensitive photo Darlington transistor is used with a CMOS nand gate. The circuit detects light and triggers a siren. You could add your own triac or relay and switch practically anything. The kit uses the MEL12 Darlington super alpha phototransistor, ty

A stronger, Mecha-Medusa is a walking robot that operates with the aid of a sound sensor. Clap hands or snap fingers to command this robot to start walking on four legs. Stops automatically after a preset time. Ideal for the hobbyist or budding scientist.

Circuits that operate just like the real gameshows, where a light shows up for the first contestant to hit their answer button.

This super cool circuit behaves as a clapper-switch. You clap and the circuit turns on. Clap and it turns off. Great as a light clap switch.