Major problem fixed! -- diode/zener clamps

[Tom Cloud]

>At 12:13 PM 3/24/97 -0600, you wrote:
>>My first guess is that a slow, rectifier-type, diode was used.  But,
>>a zener is as slow, if not slower.  The diode allows the coil to go
>>to a high voltage in one direction and clamps it to about 1 volt
>>in the other.  The zener clamps it both directions -- go figure.
>
>Doesn't the zener allow some of the energy of the collapsing mag
>field to cause some flyback effect while a clamp diode to the supply
>limits the flyback to Vss + .6v or so?
>
>So I would guess, limiting the flyback voltage would result in more
>current, maybe enough to keep the solinoid energized longer.
>
>Fred

a zener IS a diode.  It just has a lower reverse breakdown.  So,
both the zener and the diode will clamp in the forward direction
at ~.6-.7 volts, but the diode will allow the coil to swing
in the other direction as far as it wants (unless its reverse breakdown
is exceeded) whereas the zener will limit the forward swing also ...

Tom Cloud <cloud at peaches.ph.utexas.edu>