Thoughts on GW-Instek 3303S Supply?

[icpart]

I have looked at the schematics and did a simulation of the simplified (only CV mode) circuit for channel 3.

Hi. I also bought that GW-3303S a week ago from USA and now I tried to understand how exactly work CC/CV circuits of that power supply, because I think in the future to mod eventually Channel 3 of that power supply with external control via  USB DAQ and maybe Labview or manual control via potentiometer. Can you share your simulation files with us or you can send me PM about that if you agree to share them.

[Kleinstein]

Attached is a model that approximated the GW 3303 - channel 3 with 2 modifications to reduce the peak on turn on and CC-CV transition.

The added parts are R12 and C5  (the first step of modification) and
C8+R13+R11. The second change only make sense together with the first change.

I chose the LT1057 for the TL072 and the IRFP250 instead of IRFP150 to use only parts from the std. lib. R1 is changes to 0.15 Ohms to include resistance of the wire. The current part is missing the extra amplification step and thus might react a little different.

I notices that an easy change would be reducing the positive supply voltage (initially I had a lower value and thus smaller peaks).