How can I build a SR flip flop using op amps? (for a hand made 555 timer) Transistors may be used. I was thinking of using a hysteric op-amp and putting a schmitt trigger on the input of comparator 2. However, my solution fails in simulation. Here's my current circuit.
It works with the LTSpice model of a SR Flip-Flop so I know everything else is working as desired.
Best Answer
Have a look at the Vo-Vi curve of a hysteresis cycle:
simulate this circuit – Schematic created using CircuitLab
If you are able to force Vi above the positive threshold, the output will go high and will stay there when Vi returns to 0. If you you force Vi below the negative threshold the output will go low and stay there forever.
You can achieve this (well, actually the inverse) with
simulate this circuit