[Elecraft] Inductive Kicks

[Jack Smith]

It's still the case that the diode will extend the release period. t = 
L/R so a typical small relay, such as the Omron parts used in the K2 and 
K3 with 2 H inductance and 1Kohm resistance have a time constant of 2 
ms. The time constant is not necessarily the same as the release time as 
there are both mechanical and electrical considerations, but it should 
give an idea of the magnitude of the release time. With the short L/R 
time constant of these relays the diode clamp does not make a huge 
change in release time.

In the days of electromechanical switching offices, the Bell System used 
wire spring relays constructed with a large copper slug to intentionally 
lengthen the release time via a circulating current and associated 
magnetic field. I recall about a one second release period could be 
achieved with the largest slug.

Jack K8ZOA


ALAN GARD wrote:
> Hi All
>  
> Interested to read the mailings on this topic.  I've not seen any reference to an effect which used sometimes to catch us out years back when using diodes to "de-click" audio installations. Shunting the coil with a diode (at least with the rather big telephone-type relays of the period) significantly delayed the release time.  Maybe that's not so noticeable with more modern, miniature relays storing less energy?
>  
> 73 de Alan G4LWA
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