Hello all,
I have been working on a project in which I have to allow the potential difference of 5V across the terminals of a 5V relay only when the digital pin of the micro-controller goes to 1. Other wise nothing. I want it to be real-time, so that whenever the digital pin goes from 0 to 1, the current should flow across the relay. I would appreciate if any one could share a suggestion of doing it. Thank You.

- EG

 

Can you provide a schematic? It might be as simple as a transistor buffer switch… but without some clarity as to what you mean by current flowing across the relay, it's hard to definitely answer.

 

Is this something like you are looking for? Transistor , just about any NPN like 2N3904. Assume "1" is a voltage of 3 to 5 V.

 

Day dreaming and forgot to up load.

 

Day dreaming and forgot to up load.

Missing a diode across the relay coil.

 

Another option for driving a load from high impedance source is the 2n7000 mosfet.
Max.

 

Don't forget to put a diode across the relay coil to absorb the inductive kick- install with cathode facing the positive power rail.

 

Don't forget to put a diode across the relay coil to absorb the inductive kick- install with cathode facing the positive power rail.

Like I said in post #5.