[Amps] Relay Speed UP Circuit

[Paul Christensen]

>I have been looking at the K1KP (K6XX) relay speed up circuit and I am not 
>quite following the his description he has on his website.
>
> Anyone understand what's going on? How does anything placed in series with 
> a relay coil make it go faster when it seems a straight piece of wire 
> would be better.
>
> What am I missing? Jay W2IJ

Jay,

See his description in the yellow box on the .PDF version:

http://members.cruzio.com/~k6xx/radio/fastrely.pdf

You're thinking that components placed in series with the coil would 
decrease current -- and actually they do to a small extent but only after 
the relay is engaged.  But before the relay is engaged at power-up, the 
capacitor is charging to a voltage higher than the normal relay supply 
voltage.  Then, when the relay is keyed, the coil is shot with a short burst 
of DC voltage, between 1.5x - 2x the normal supply voltage.

Shortly after the relay is engaged, the capacitor dissipates and 
approximately normal coil voltage is restored.  A short increase in voltage 
results in a short increase in coil current.  Within reasonable limits, a 
short burst of elevated voltage applied to the relay results in accelerated 
operation.

Paul, W9AC