[volt-nuts] Practical power supply noise testing

Bruce Griffiths bruce.griffiths at xtra.co.nz
Fri Jul 1 20:28:08 EDT 2016

Its certainly a good way to quickly check if anythings drastically wrong and one could even compare them with a known source such as an LM317 based regulator with no ADJ pin bypass. If one can hear the noise then its possible that a sound card could make some meaningful measurements of the headphone amp output.
John, do you have any specs for the supplies?It would be nice to know the likely best case output noise level.
To measure the ripple of most supplies I usually just connect my USB scope (dc coupled) to the supply output.This certainly works (with my 14 bit scope at least) with E3610A/E3611A series supplies. For lower ripple supplies I use AC coupling.
The 100Hz (in my case) ripple shows up nicely in the FFT. 


      From: Poul-Henning Kamp <phk at phk.freebsd.dk>
 To: Discussion of precise voltage measurement <volt-nuts at febo.com>; Brooke Clarke <brooke at pacific.net> 
 Sent: Saturday, 2 July 2016 11:28 AM
 Subject: Re: [volt-nuts] Practical power supply noise testing
In message <5776E31D.7090404 at pacific.net>, Brooke Clarke writes:

>Instead of headphones something like the HP 4395A [...]

Well, there is a slight difference in price there, isn't there ? :-)

Poul-Henning Kamp      | UNIX since Zilog Zeus 3.20
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Never attribute to malice what can adequately be explained by incompetence.
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