[chbot] Snubber circuits
list57 at top.geek.nz
Tue Nov 20 19:36:19 GMT 2018
On Wed 21 Nov 2018 00:14:56 NZDT +1300, Peter Harris wrote:
> It turned out that there was a spiral cut in the metal film at one end of
> the resistor presumably to trim the value and when a voltage spike hit the
> snubber is would spark across the film at the end of the spiral burning
> some film away.
Very useful posting, thanks Peter! What was the voltage rating of the
resistors? And the spike voltage?
Your experience would confirm 2 things if my suspicion is corect: The
snubber resistor must be rated for the spike voltage (the capacitor
probably too), and carbon film resistors are more tolerant to voltage
spikes exceeding their design rating. Or, resistant to spikes exceeding
their design wattage??
I remember it being very easy to blow up 5W ceramic resistors by
discharging a photographic flash capacitor into it. It didn't even get
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