[Boatanchors] TCS Tx & Rx

[J. Forster]

With a simple magnetic circuit geometry, like a solenoid with a plunger,
it is straight forward to analyze. You really only need to know a few
parameters to get a closed form result.

However, if the relay has a swinging armature, like a door, it is much
harder.

To analyze the thing you need the inductance as a function of armature
position.

-John

===============



> A single diode, regardless of whether you are protecting the key
> contacts directly or hanging it on the offending coil, does in fact
> affect the dropout time of the relay significantly.  Back when I was a
> young engineer, I designed relay testing equipment for high reliability
> weapons, and that fact was drilled into me big time.  There is a good
> rundown on the various methods of suppressing the spike from the
> collapsing magnetic field at
> http://www.pickercomponents.com/Pages/Application%20Notes/Coil_Supression_vs_Relay_Life.pdf
>
>
> Included on the second page is a chart of dropout time increase versus
> suppression technique that is more than illuminating.  A diode in series
> with a zener of approximately double that of the coil operating voltage
> is what we used in our circuit designs - the reason should be clear.
> Obviously you have to choose the zener rating carefully to manage the
> strength of the collapsing magnetic field, which varies with the size of
> the relay.
>
> 73,
> Mike
>
>> >  I'm no CW op but I'd expect the diode would lengthen the relay
>> release
>> >  time, maybe quite a lot.
>>
>>
>> Some passive parts across the key might have a noticeable effect like
>> that but the backward diode doesn't have any timing effect. If there is
>> one it would take lab equipment (atomic clock?) to measure it. At morse
>> code keying rates any stretching that might be there is 'virually'
>> nonexistent. And..it *DOES* get rid of that spike induced when the
>> magnetic field from the relay coil collapses. It's highly recommended in
>> solid state circuits to preserve keying transistors that are used to
>> energize relays.
>
> ______________________________________________________________
> Boatanchors mailing list
> Home: http://mailman.qth.net/mailman/listinfo/boatanchors
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:Boatanchors at mailman.qth.net
>
> List Administrator: Duane Fischer, W8DBF
> ** For Assistance: dfischer at usol.com **
>
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
>