does an SCR look like a diode physically?
i found this:
silicon-controlled rectifier
(SCR) Three terminal active device that acts as a gated diode. The gate terminal is used to turn the device on allowing current to pass from cathode to anode.
so it's just like a transistor? apply current to the base and current flows from C to E? in this case, apply current to the gate and current flows from + to -?
how are these rated? do i need just like a 9v or 3v or whatever i run the circuit on SCR?
so if my understanding is correct of SCRs, then for this application, why does opening the lower switch apply voltage to the gate?