Simple SMPS of considerable power

[kaip]

It has been a while.
This design is supposed to be simple, almost minimalistic.

Mains: 230VAC
Out: about 2x50VDC (adjustable, and with other L5 winding could be anything you want)




I have some questions about component choice:
1. What is the max current rating I should use for the 12V trafo. I chose 8VA to be on the save side. Can I get away with less ?
2. Secondary filtering: L3 and L4 what are the best types to use. Ready made, or should I wind them myself . Is there an easy calculator for this ?

 

[zs1adc]

Hello Kaip.
I do not have a answer to you questions but I hope you can help me.
I know this post is old but I'm hoping you will answer me.
If you can will you please share any info you have to help me to build it.
Thanking you, regards, Reg.

 

[KX36]

The frequency compensation's wrong and there is insufficient creepage distance between primary and secondary.

The attempted compensation of a 100nF cap from the comp pin to ground won't work as the SG3525 uses a normal voltage controlled opamp as an error amp, no an OTA. If it was an OTA the compensation is to ground, normal opamps would be a local feedback to the inverting input. As well as this, it would be a voltage mode control which generally requires type III compensation which this doesn't have. Not much point in me going further because this is an old thread.

 

[kooroshi60]

I built this SMPS. it does not work properly. Transformer saturates instantly because the feedback circuitry is wrong.
This design can have more possible problems. Not recommended!