Below is schematic of self-powered(by passing little current not enough to operate) switch reverse-engineered from PCB.
Zener diode(D7) seems like 1N47 but not sure.
This is connected in serial with load. (one to mains live and one to load)
I omitted fuse and inrush current limiting varistor
How does this exactly work and is there a name for this circuit?
As far as I understand:
- R3 and C2 is for smoothing
- D1, D2, D5, D6 is diode bridge
- C3 is for smoothing
- D7 is for limiting voltage
- When S1 is closed, current flows into R1
I can't figure out the purpose of D3 and D4/C1, R4, D8, D9 and S2/L1 and how it limits current(resistor value seems too small).
Also how can I calculate current?