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DC 120V converter circuit

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New Member
I have many strings of LED Christmas lights, but they flicker on 120 VAC. If I could feed them 120 VDC, that would solve the problem. Simple bridge/filter circuits produce 170 VDC, wchi will burn out the lights pretty quickly.

I've come across a few circuits that seemed unnecessarily complex and expensive; I need something relatively simple and cheap. (I'll be making quite a few of these.)

All suggestions gratefully appreciated!



Well-Known Member
Most Helpful Member
The lights may well be OK on full-wave rectified mains. I've converted several sets of lights that way.

The mains here is 230 V ac 50 Hz but the voltage ratio between rms and peak is the same.

There are many different circuits used. Some circuits have half the lights connected with one polarity and half with the other so they won't work on dc.

You could put a suitable capacitor in series before the rectifier to limit the current if you wanted to. Alternatively you could use a resistor, before or after the rectifier.


Well-Known Member
Most Helpful Member
The string probably is half-wave rectified. In your circuit, keep the bridge and delete the filter capacitor, and let full-wave rectified AC drive the string. This will increase the flicker frequency to 120 Hz.

Note - depending on the string's internal circuit, it might not come on at all with full-wave rectified, pulsating DC. In that case, reverse the plug so the string sees the opposite polarity of pulsating DC.

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