Ok, I know the basic function of an optocoupler is "turn on irLED, triggering a phototransistor and allowing current to flow"; an optical off then on switch.
Is there a reverse optocoupler, i.e. "turn on irLED, unknown component is triggered and stops/blocks current flow", an optical on then off switch?
Circuit A does something that includes a charging function then activates Circuit B. As long as Circuit B has [enough] power, Circuit A is removed from it's power source (turned off) by a signal from Circuit B. When Circuit B's power is gone/too low, signal is removed and Circuit A's power is returned and starts process over again.
I know how optical relays work (Circuit A on, Circuit B off, trigger on, Circuit A off, Circuit B on, trigger off, original condition). A standard optocoupler is essentially one half of this. I am wanting the other half.