P3D Re: PHOTO-3D digest 2651 -Forwarded

[Bob_Maxey@xxxxxxxxxxxx]

>>When using high current/low voltage bulbs in viewers, you have to worry
about light flickering, which is caused by oxidation in the switch
contacts.  I am now looking into installing a "microswitch" like Dave
Burder has done in the modified Sterolists.  It is not clear to me how
these switches work.  Is there a contact made?  If it is, why would
these switches eliminate flickering? (as some people claim - I have no
personal experience)

Dr. T: Here is my experience with Microswitches (Actually a trade name but
used generically). There is a contact made, and there are several different
types of switches. You can get sealed ones and ones that are not sealed.
What can happen is because the voltage is so low, the normal spark that is
created is not strong enough to help keep the contacts clean. Oxidation
forms and the switches performance is degraded. This also happens with
small low power relays.

The sealed type do not allow air in so oxidation is kept to a minimum. If
the voltage is high enough, the arc that occurs when the switch is actuated
helps to clean the contacts.

Do a web search for "Cherry" - they make a large variety of these switches.
You can also get them with extended metal roller arms which can be bent and
reformed to be used in viewers.

RM



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