[GreenKeys] Snubbing of selector magnet

[John Nagle]

On 7/21/2013 7:55 PM, greenkeys-request at mailman.qth.net wrote:
>> > Mostly the snubber affects what happens on the transition from Mark to
>> > Space. And quite frankly, unless you've put an enormous value of C in the
>> > snubber, the Selector magnet is going to pretty much going to let go when
>> > the loop opens up.
>> > 
>> > However, with too small a value, the over shoot and ringing issues are going
>> > to beat the hell out of the loop keying circuit.

   Right.  Fortunately, modern optoisolators like the Omron G3VM-401B/E
can handle sizable voltages, like 320V.  Enough snubbing to get the
spikes down into that range isn't hard.

   There's an argument for an R/C snubber instead of a diode.  A diode
effectively shorts the selector magnet during the MARK/SPACE transition,
so the current drops more slowly than merely opening the circuit.

				John Nagle