• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

help with light activated relay ...

Not open for further replies.


New Member

on tony's light activated relay schematic is there any way to use it to power up some type of "appliance", eg a lamp, fan, etc, using this circuit. If so, what type and spec relay would i need, and would any adjustments need to be made to the schematic itself?
or does anyone have a circuit that can already do this?

any help appreciated.




If you intend to run the circuitry from a battery, no adjustment is necessary. Just wire the relay contacts into the active (hot) conductor of your appliance.

Your relay must be a type with a 6V DC coil, and the contacts must be rated to your mains voltage (110/120/230/240V - depending on where you live), and have a current carrying capacity of at least whatever your appliance draws.

If you want to do away with the battery, and supply the circuitry from the mains, use this modified schematic:

(NB, I have written 240V on the primary of the transformer, however, if you live in a 110V/120V area, obviously, you should use a 110V-6V transformer. The transformer need not be large, only 500mA approximately)



New Member
i think that a very small 150mA transformer is enough. it is just a relay and some simple components. what do you think you need 500mA for.
depending on the relay you could do with 50mA!!!


New Member
You should know that relays have two ratings. The sensing side should match the circuit (perhaps 6 volts DC @ 100 ma). The output side (the contacts) also have a rating which should match the appliance you are powering (perhaps 120 volts AC @ 2 amps). When selecting your relay, please consider BOTH ratings.
Not open for further replies.

Latest threads

EE World Online Articles