Re: gEDA-user: buzzing board

[andrewm <andrewm@xxxxxxxxxxxxxxx>]

DJ Delorie wrote:
> 1. How do you find out where such a noise is coming from, when
>    everything is so close together?  Neither a stethoscope nor a straw
>    were helpful.
>
>   
Get an electret mic running off a battery on one scope lead

Probe around with other scope lead to see what is in sync with it just 
to make sure you
are looking at the right part of the circuit.  You could spend ages 
looking at that switcher
for the OLED and find out that the buzz was a slightly different 
frequency coming from
somewehere else.

Next you can get a peizo element and solder some whiskers to it and use 
that to probe
components for the same noise.  With contact from the whiskers you maybe 
able to
track it down further than a straw/stethescope could

> 2. What kind of components *can* make that kind of noise?
>
>   

Anything from inductors and electro caps through to actual copper traces.




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