Suggest operating voltage for relay

[jay_3189]

I Want to use Relay in my Circuit of which contact of relay I've joined with 24V Battery with Valve(Operate at 24v and 0.5A) and at other side with BJT Transistor that yet I've not desided the no. of transistor which connected to controller pin through register. so suggest me the relay operating voltage which most suitable here in my circuit.

 

[PA4TIM]

Sorry but I have no clue about what you want. The operating current of the relay coil can be to much for your " unknown" controller, so in that case you need a transistor or mosfet to switch the relay or let a mosfet switch your valve direct. For a mosfet you probably need a mosfet driver but with that minimum info you gave my cristal ball stays dark. The transistor can be operated direct from the most controllers (do not forget a base resistor) but the type depends on the current your relay needs and the relay depends on the voltage rails available. I would use the 24V to switch the relaycoil is its a big one.

So more info, place your schematic, what voltage rails, what controller, how much current the valve needs etc.