Electronics > Projects, Designs, and Technical Stuff
Chinese 0-30v 3a psu issues
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m3vuv:
just built this kit,schematic attached,it works fine but if i turn it off when its in cc mode i get a brief spike on the output,in cv mode its fine,is this normal?,if so it there a fix bar chucking it in the bin?,regards m3vuv
RIKRIK:
This reminds me of the old school power supplies , lm358 http://www.electronics-lab.com/project/0-30v-laboratory-power-supply/ , I'd say it's a keeper, have you tried turning the current and voltage fully down on power off, apart from that, have a tinker with it, for hobbyist electronics it should be fine. Fingers crossed .
ledtester:
This looks like the 2ma-3A, 30V power supply kit that has been much discussed on this forum.

Have a look at this thread and, in particular, the comments by Audioguru:

https://www.eevblog.com/forum/beginners/bangood-psu-enhancements/
m3vuv:
if the current and voltage are turned fully down it wont do it as its then not in cc mode,its only in cc mode that it does it.
floobydust:
It's a design issue unless you assembled the kit wrong. The original design was copied from 1978 (Practical Electronics 1978 October) and used LM741's.
https://www.eevblog.com/forum/beginners/0-30v-0-3a-psu-audiogurus-version/msg2239764/#msg2239764
R13, R14 were changed for better control of switch on/off spikes, I think 160R and 12k in Rev. 7

Normally, when power is switched off, C3 discharges first then Q1 turns on to shut off the output, until C1 is discharged. But under load, C1 can discharge first so the +ve rail sags and the op-amp outputs a nasty blip. The PSU needs an output off switch, or undervoltage lockout added.

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