:smile:Feeling somewhat dumb at the moment. I need a VERY simple latching circuit that will simply be on until a signal hits it (can be either + or -, I have no preference) and the circuit will remain off until I reset it.
I have been playing with SCRs and stuff but apparently my current draw isn't sufficient to get them to stay in saturation.
So I went to a S/RS Flip Flop arrangement using an ANCIENT 7400 chip and that works well... as soon as a signal hits the input of one of the gates it flips and stays put until I put the signal to the Reset input and it goes back, no matter how many times I wiggle the input. (Note - the 7400 chip I used I have had since I was a kid - literally got that in the 1970s, and it's still working. Love those old 7400s!)
I remain convinced however that there should be a way to do this with a single transistor that feeds back onto itself, but I can't quite get it to work.
So I'm either looking for that magical single-transistor circuit, or a more up-to-date and perhaps more efficient circuit than the 7400s wired as S/RS Flip Flops. I need 5 of these circuits, that would be 3-7400 chips. Is there anything like a "hex S/RS Flip Flop" on a single chip? :-)
Thanks for the ideas, should any come forth. If worse comes to worse, I can live with the 7400 arrangement, but my gut is telling me there has to be something better.