plus you get back EMF, which means that when you switch the relay off, the coild discharges a current in the opposite direction back into your circuit.
Thank you. I went ahead and purchased the relay. I'm not sure how to use the transistor circuit with the diode. When I tried using a 5v relay with a 5 volt transistor with no diode or resistor between arduino and transistor, the circuit did not work. Newby Anyways, what if I just put a diode from arduino to relay? Doesn't a diode prevent feedback?