I am having some trouble trying to trigger a relay. The only signal that i can find on my PCB has a very low voltage of around 0.7v when it receives a signal it jumps to around 1.4v. Here is the kicker.... the 0.7v signal and 1.4v signals are not constant. It seems to be some type of pulsating signal about every half second it goes from 0v to 0.7v and when triggered it goes from 1.4v to 0v every half second. So what I would like to do if possible is to trigger a relay somehow that can sense the voltage change and stays closed regardless of the pulse. Then when it goes back to 0.7v it would then open again. Sorry, I am a novice at any type of circuit. Any help in the right direction would be greatly appreciated. Thanks!