Electronics > Repair
18V/3A HY1503 PSU - weird CC/CV behavior while charging battery cells
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iMo:
The transient test will come next week, I need some low L higher power resistors for the load at the shorter and some rugged construction for it as well..
xavier60:
I did more experimenting. The 120pF that I though was ok to put across the inputs, isn't.
And it has just occurred to me that even with a large capacitor between output and Inverting input of the CV opamp, the response can never be purely Integral. The AC or proportional gain can never be lower than one.
 
iMo:
Here is the CC and CV out with only 1n ceramic in the CV fb only (330p at 741's inputs removed).
10k in 741 in- is there.
xavier60:
Maybe it's oscillation in the output stage. If so, the signal should be a bit stronger on the anode of D12.
iMo:
 :palm:

I've removed the rather long leads (my really bad idea) from the shunt (the 0.33ohm placed in rear part of the box) to my new switch on the front panel (creating a loop antenna) and all oscillations are gone.. (with 1n only in the 741 feedback). What is left are the couple of mVpp 100Hz ripples at the CV and CC opamp's outputs.
I will make the transient test next weeks.
Also I have to solve the 200mA/3A switching as well as I need the lower CC range as well..
Thanks!

PS: ok.. when not having an oscilloscope handy I would consider my idea with the switch pretty  8)
 :D

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