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From: john larkin <JL@gct.com>
Newsgroups: sci.electronics.design
Subject: Re: power supply discharge
Date: Sun, 29 Sep 2024 10:21:25 -0700
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On Sat, 28 Sep 2024 10:21:46 -0700, john larkin <JL@gct.com> wrote:

>On Sat, 28 Sep 2024 09:44:44 -0400, legg <legg@nospam.magma.ca> wrote:
>
>>On Fri, 27 Sep 2024 08:07:29 -0700, john larkin <JL@gct.com> wrote:
>>
>>>
>>>Given a benchtop power supply, you can turn the voltage up and then
>>>down, and it goes down. Most have a substantial amount of output
>>>capacitance, and can be driving an external cap too. So something
>>>pulls the output down.
>>>
>>>I guess that there are no standards for this, but I've never seen a
>>>supply that just hangs high when it's cranked down.
>>>
>>>I'm designing some programmable multi-channel power suplies and that
>>>is one of many tangled issues in the project.
>>
>>Twiddling the adjustment knob on a bench supply doesn't 
>>represent a dramatic change - and most adjustible 
>>supplies don't load their output terminals with a 
>>lot of capacitance.
>
>I've measured a few, and got output terminal capacitance of a few
>hundred to maybe 2000 uF.
>
>People here might measure some random power supplies. I leave them off
>and connect to a 50 ohm sinewave-output function generator and find
>the -3 dB point. One could use a square wave and scope the slopes too.
>Keeping the amplitude low will avoid turning semi junctions on.

Come on guys, quit pontificating and start measuring.