[sdiy] Snubber Capacitors

[Richie Burnett]

Snubbers across bridge rectifier diodes in 50/60Hz supplies are there to damp HF
ringing that occurs when the rectifier diodes abruptly switch large currents. 
You really should include some series resistance too, as adding capacitance
alone just lowers the ringing frequency but does little to damp it.

This document explains how they work and how to design them:

http://www.hagtech.com/pdf/snubber.pdf

Page 7 onwards deals with low-frequency "conventional" power supplies.

-Richie,

> Hi,
>
> I'm designing a power supply for my synth. I want to put snubber caps
> for the bridge rectifier on the PCB in case I find a need for them, but
> am not sure whether to have one across each diode, or just one across
> the bridge. Also sometimes a series RC circuit is used. Would it be best
> to include room for a resistor as well?
>
>
>
> Regards,
> Stewart.
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