Re: gEDA-user: buzzing board

[DJ Delorie <dj@xxxxxxxxxxx>]

> Or is it reacting too quickly?  Some power supplies need a minimum ESR
> so that the output cap acts as an RC filter.

The LDO has its own bypass cap (0.1u) at its terminals.  The 4.7u is
after the transistor that enables the rail to the OLED.  It buzzes
with both PNP and P-MOS, and those should provide sufficient
resistance to avoid ringing that way.

Besides, as I've said before, the ringing's waveform corresponds to
the data on the OLED, like a video signal.  It's not a constant ripple
like a power supply problem, and goes away when the oled is filled
with all dark pixels.


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