Driving 12V from arduino

Hey guys,
I am trying to drive a relay from my arduino, and i cannot get it to work. Here is one of the circuits i have used:



I have tried using a 3904 aswell, even different base resistors, 10k, 1.2k.
Still the relay does not activate.
The coil is 325 Ohms.
Does anyone have a tested circuit that works?
Thanks

That should work fine - but 22K is too high, use 1K or 470 ohm (to ensure the transistor switches fully). It's also a good idea to add a resistor across BE of the transistor to help it switch OFF, but it will work fine without it.

If it's not working, then you're doing something wrong - such as connecting the transistor the wrong way - or have duff components.

Yeah, maybe the transistor is blown. I checked it on my multi meter though - was fine. I'll get some new ones just to make sure.
Thanks though, i'll use a 560 Ohm since i have like 2 million around here. What resistance should i put across the BE junction?

This circuit isn't just for the arduino. It's also for the latch circuit I was on about recently

BioniC187 said:

Yeah, maybe the transistor is blown. I checked it on my multi meter though - was fine. I'll get some new ones just to make sure.
Thanks though, i'll use a 560 Ohm since i have like 2 million around here. What resistance should i put across the BE junction?

Click to expand...

Use the 1.2K you mentioned earlier.

Well, i got it working. Used 560 Ohm resistors. Circuit works great, i even hooked it up with my latch circuit, and the whole thing works great
thanks