I am evaluating a new controller and see a circuit I do not quite understand. I've built the circuit and I see the following (see image), but not understand why. Can someone please give me the name of this circuit so I can look it up?
Bottom line, I do not understand how the cap and resistor in parallel = DC.
It is a capacitive power supply with a half-wave rectifier. Most of the grid voltage is dropped on the capacitor due to its impedance. The rest is rectified and regulated using a Zener diode.
You must be careful when using this kind of power supply because it is not isolating the grid from low voltage side. Also remember that special (X-rated) capacitor is needed in order to provide minimum security.