Hi,

I am new to electrical world but I have some experience programming micro-controllers. I want to use a relay to make/break a 230v AC supply. The relay should be able to take the control input from a GPIO pin of a micro-controller( a PIC micro) and it should be of a small from factor( say 5cm*5cm*2cm). As I have no experience in choosing relays, any help is greatly appritiated. Thanks in advance.

-rohit

 

First of all check how much ampere load on the AC you need to run at 230V, like 10 or 20A and also how many poles, like single, double, triple pole. Then check what your supply voltage is to run the relay, like 5,6,9 or 12V. Then you will need one or two transistors to amplify the output of your PIC to drive the relay.

When you have answers for the first three questions, go to an electronics shop get a relay with input as specified,no of poles, load capacity and an impedance of atleast 200ohms. For the size you specified, you can get triple or more poles but double pole will be suitable for you mostly. Remember, the more number of poles, the bigger the relay gets.

 

You can also go for a solid state relay which is costlier and works with a wide range of voltage and current and is isolated with no noise at all as it is full electronics.