I would say if possible, next test it with a fixed duty cycle to see if taking the feedback loop out of the equation makes a difference. That can eliminate one source of nasty transformer hiss, especially if the hiss changes when you probe it with the scope. I'd recommend putting a class Y2 capacitor from primary to secondary ground for starters. This goes for res_smps too, your simulation is oscillating, presumably from an unstable feedback loop. Normally even if it's an unstable feedback loop that oscillates, it will oscillate around the right DC point. Your feedback and compensation circuits don't looks right but I'm not entirely sure that's your problem. I also tried replacing the 36v zener diode with other voltages. Diodes I have used for the secondary bridge are BYV79-200 (200v 14A 30ns ultra fast rectifier) Today I noticed that the HISS (saturation noise) is still there even if I connect a load to the outputs. I have regulated 12 volts for SG3525 and IR2110 supply. The primary is 26 turns and secondary is 4 turns X2. This SMPS is capable of delivering 864W of power when ETD59 core is used.

It's a 50Khz half bridge smps with the 300 volts of input voltage. So, I recalculated the transformer design and did a new winding.

What would you suggest me to do? Maybe zenner diodes put reverted? I checked every single part one by one, four or five times.Д®very thing was correct. (ExcellentIT calculations) I expected everything to run smoothly but after running it, all I get in the secondary output is +/- 2 volts!! Also the transformer makes an unpleasant noise. So, I used a 36v zener and as for turns ratio, (Primary 26 turns of 1.7mm ) and (Secondary 2X4 turns of.7mmX5) are my winding. The only difference is that I adjusted the circuit for +36/-36 volts. I built it using the exact same parts written in the schematic. Hello everyone, I made a 50Khz SMPS using the schematic I have attached to my message.

Sg3525 ir2110 smps rar files