Low current cut-off circuit
I also need some advice on using comparators:
I'm trying to design a simple circuit that cuts-off when the current through a time-varying load falls below a threshold value.
Basically, I am electrochemically etching a piece of wire, which initially has a resistance of ~1k Ohms. When the etching is complete the resistance rapidly (few 100ms) increases to essentially an open circuit, at which point I want to automatically break the circuit. The etching requires a constant voltage of ~3V dc.
I've tried to design a comparator circuit to do this, but the problem is that the input (sense) voltage has to have some feedback from the output circuit driving the etching, and my mind starts melting.
I can attach rough schematics if anybody feels they can help.
Cheers.