Electronics > Projects, Designs, and Technical Stuff
Switching Noise
engrguy42:
Sorting thru some old boxes and found an old PC power supply. Was about to trash it and decided to hook up the scope and see if it was still breathing.
Attached is the AC coupled trace on the 12V output with about an amp of load on it. Wow, that's some switching noise...maybe 5v peak-to-peak.
Anyone know what the culprit might be? Not really interested in a science project right now, but if it's one of those "oh yeah, that's obviously xxxxx" I might tear it open and replace it.
Thanks.
Benta:
One thing to know about old PC power supplies: they need a minimum load on the main output (+5 V) to work correctly. Try with 2 A.
After that, your measurements may look different.
engrguy42:
--- Quote from: Benta on May 28, 2020, 07:12:58 pm ---One thing to know about old PC power supplies: they need a minimum load on the main output (+5 V) to work correctly. Try with 2 A.
After that, your measurements may look different.
--- End quote ---
Thanks. Yeah, tried almost 2A on the 5V and no difference.
jemangedeslolos:
How did you probe it?
engrguy42:
--- Quote from: jemangedeslolos on May 28, 2020, 07:19:32 pm ---How did you probe it?
--- End quote ---
Just a differential probe across the load resistor
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