bob prohaska  wrote:
> Computer Nerd Kev  wrote:
>> bob prohaska  wrote:
>>> Has anybody used a USB sound capture device for an audio frequency
>>> oscilloscope on a Raspberry Pi? xoscope is available using apt,
>>> but I can't find any reference to what sound devices, if any, it
>>> can use over USB.
>>
>> Xoscope's webpage says it supports ALSA as an input source, so as
>> long as a USB audio adapter is working with ALSA (the cheap Chinese
>> ones seem to do so without issues) it should be fine.
>>
> Ok, that's a good hint. I'm looking at something like:
>
https://www.amazon.com/DIGITNOW-Capture-Grabber-Cassette-Converter/dp/B079CBGDS
T/ref=pd_rhf_dp_p_img_2?_encoding=UTF8&psc=1&refRID=YV3EVDFX4FWZF58TY2CW
> There are reviews saying it works with Raspberry Pi, so maybe it'll work
> with xoscope.

Xoscope just listens in on the audio stream, so if other ALSA audio
programs work, it will too.

These sorts of adapters are cheaper and also work on the Pi (I've
used one the same as this, but only the audio output):
https://www.ebay.com/itm/303879860060

It even works on a old Linux installation via OSS (again only
tested output).

>> Of course at this point you've got a significant amount of
>> front-end circuitry for your "simple" sound card oscilloscope. For
>> a data logging application that might be quite reasonable, but for
>> basic troubleshooting maybe it would be easier to just buy an old
>> CRO (Cathode Ray Oscilloscope), which has the added benefit of
>> working outside the audio frequency range.
>
> I'm experienced with analog 'scopes and don't want one. They aren't
> useful for catching one-off transient events, which is what I'm looking
> for. Something with a stop trigger is essential. A freestanding DSO
> would be nice, but I won't use it enough to justify the cost and storage.

Fair enough, your power supply monitoring is more of a data logging
application anyway. Possibly the slowest speed setting on a CRO
combined with a video recording of the screen would work. You'd
need to have all the settings worked out fairly well though and
that would be a hurdle for a first-timer.

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