Hi all.
I am doing a AC-DC 0-200V Variable Power Supply Without Transformer. The OP got good result at:

and I used 110 V ac input, and R = 510K (OP used 560K), got the lowest V = 6.2 Vdc, how to get 0V? what's the reason? how to calculate the value of R?
Thanks

 

Hello,

I would NEVER use that circuit.
It has no isolation from the mains and will be leathal.

Bertus

 

hi Laoad,
My advice would be not build or use a non mains isolated transformerless PSU.
E

 

Why would you need to convert AC to DC just to dim a light bulb?

How many other uses would you have for the waveform produced by that?

 

If you need to ask, you're out of your league and should find something safer.

I strongly advise ignoring any circuits using schematics like that. The people drawing them are unlikely to know what they're talking about. If they did, they'd put down their crayons and provide a real schematic.

 

Thanks to all.
I'll give it up.