[GreenKeys] Snubbing of selector magnet

[John Nagle]

On 7/22/2013 8:34 AM, Jim Haynes wrote:
> On Mon, 22 Jul 2013, Chris Elmquist wrote:
>>
>> yes-- so if we choose an opto that can handle anything as big as the
>> spike, we probably don't have to snub it at all.
>>
> Well, unless the turnoff is at least a little bit slow, the spike will
> rise in voltage until something stops it, whether by snubbing or by
> breaking down.

   Right.  The voltage for the first few nanoseconds when an inductor
dumps can be huge.  Power semiconductors can often survive some of
those, but there's cumulative damage.  The caps used in snubbers should
be ceramics with high voltage ratings. I used 500V caps, after observing
400V spikes on a scope.

				John Nagle