Electronics > Repair
18V/3A HY1503 PSU - weird CC/CV behavior while charging battery cells
<< < (8/15) > >>
xavier60:
I wasn't having much fun at all until I realized that I shouldn't have omitted the 10 ohm Base stopper resistor.
For the compensation, a 2.2K and 150pF gave fast stable response, 3us. Just a 470pF gave a slower stable response, 10us.
As I discovered, it's possible to have oscillations in localized areas other than the whole loop.
xavier60:
470pF and 2.2K improves tolerance to capacitive loads.
First is a load transient test with a 470uF POSCAP directly across the output.
Then with a 0.1 ohm in series with the POSCAP.
The trace is inverted as I'm looking at the negative output WRT +Ground.
iMo:
I disconnected the 330p at 741's inputs and wired 100ohm in parallel to the 1k at BE of the 2N3055.
It did not help with jumping voltage at switching ~10ohm load on/off.
I returned the 330p between the 741's inputs and the jumping voltage is gone.

PS: as you are well equipped - could you try the 100pF between pin5 and pin6 of the 741 as in the original - how it affects stuff, plz??

PPS: below the transient at the posts when I switch in a resistor, 15V/1.9A.

.. and the 741's output, the oscillation might come from a longer lead.
xavier60:
I'm using an LM358. Even a 1000pF across the input only caused a small amount of ringing.
With a 470pF and 2.2K, mine settles in 10us.
That high frequency ringing could be coming from the wiring to your shorter.
xavier60:
Your LM741 might be faulty if it's very old. I have seen old opamps randomly develop large input offsets.
Navigation
Message Index
Next page
Previous page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod