Electronic – Bridge rectifier: What is the purpose of these two elements

bridge-rectifiercircuit analysisfilter

I found the following circuit in a random video (don't know what it's worth) and have two questions about it. I get that it's a full wave rectifier, and I think I have a decent idea on how it works. However:

  • What is the 220k resistor for?
  • Why put the 105JF capacitor in there? This looks to me like a high-pass filter, and I don't see the point at all of doing this.

full wave rectifier

Best Answer

That is a de facto circuit for cheap generic mains powered LED lamps.

The capacitor is an essential part, the circuit is called a "capacitive dropper" which is used to bring down the voltage at modest current level to power the LEDs.

The 220k resistor is necessary to keep the LEDs turned off, so that they do not glow faintly due to capacitive coupling in the mains wiring powering up the LEDs ever so slightly.