[AMPS] Hot Switching

[measures]

>
>Rich says;
>
>>Relays need to open quickly, as well as close quickly 
>>(contact bounce time included).  
>
>Open frame relays especially seem to bounce a lot. 'Speed up' by using a
>high voltage and auxiliary contacts to put resistance in series with the
>coil after relay closure doesn't help the bounce. A high supply voltage and
>a series resistor helps enormously to speed up a relay - or an old Teletype
>machine selector magnet. For fast opening, you do NOT want a diode across
>the coil. I think Rich suggested having the coil in series with the
>resistor, and the diode across the lot, which is the best way. 

No.  The break-speedup resistor is in series with the reverse emf diode, 
and the combo is across the coil.   Putting a diode straight across the 
coil is like molassas in January.  (the resistor needs to be roughly 2 x 
the coil resistance)

later

-  Rich..., 805.386.3734, www.vcnet.com/measures.  
end


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