Control 30 mA 12V relay with 2.4 mA 12V

[poser]

Hi Everyone,

I'm not really an electronics guy, but I'm trying to wire up a simple circuit to control my projector mount with the projector's trigger circuit. I have figured out most of it but ran into a small problem. The projector's trigger is 12V 2.4 mA and the relay I have is 12 V 30mA. I have gathered that I need a transistor to boost the current so that it can trigger the relay. What I don't understand is which transistor to buy, how to wire it, and what resistors and diodes I need (if any).

Any help is appreciated.

Thanks,

Joe

 

[NickS]

Sorry nobody has responded yet. This is a simple task. I looked up a relay with similar requirements to yours and it had a nominal DCR of 400 ohms so I represented it in the circuit below as a 400ohm resistor. All you do is place your relay coil in its place and away you go.

S1 represents the 12V @ 2.4mA(max) coming from the projector. The transistor will only consume about 500uA of that.

Good Luck
-Nick-

 

[poser]

Thanks!

Great, thank you for the response. Very simple and easy to understand. I'll wire it up and see if it works! Thanks NickS.

 

[Resqueline]

Thanks Nick.
It slipped me by after I didn't have the time to make a proper reply the first time I read it. Sorry about that.
Just remember to put the usual protective diode across the relay coil. I guess it goes without saying that you'll need a 12V power supply.

 

[NickS]

Sorry I forgot the didoe.