Arduino Relay? Answered
I'm working on a UPS of sorts for an arduino project of mine. Basically if the pwoer goes out I want the arduino to switch to a 9v battery backup. I was wondering what sort of relay I should use and if a transformer would be needed. Ideally I'd like to use a simple power supply with a transformer built in and then have that feed into the relay, but I'm not sure if the 7-12v from a normal arduino power supply would then be enough to switch the relay (normally closed).