[ARC5] Keying suggestions

[Kenneth G. Gordon]

On 9 Apr 2006 at 16:07, J. Forster wrote:

> With a diode, the relay will
> drop out more slowly than with an RC snubber. The reason is that with
> a diode, the coil current falls with a time constant of
> 
> L/R, where L is the coil inductance and R is the coil resistance
> 
> With an RC snubber it falls with a TC of
> 
> L/ (R + Rs) where Rs is the snubber resistance.
> 
> Basically, some of the coil's stored energy is dissipated in the
> snubbing resistor. So keying may well be better with the RC than with
> the diode.

This is the main reason I do not recommend using a "spike-catching" 
diode for a keying relay. 

In addition, IMHO, the main reasons for installing such a diode are 1) to 
prevent spikes from effecting other parts, if any, of the circuit, and 2) to 
prevent damage to the power supply.

NEITHER of these usually appears in such simple keying circuits.

Ken W7EKB