Re: TDC DC

[P3D John Ohrt <johrt@xxxxxxx>]

P3D Michael Kersenbrock wrote:


> Capacitor charges up, and that's it.  Might the capacitor
> been in parallel?

Yes, I corrected that "typo" later.



> Similar sorts of surge "protection" have been done for the last half
> century by ham radio folk ("I are one" or used to be) for the filaments
> of their power amplifiers.

Great guys to know!  The "surges" I am talking about are abrupt changes
in the nominal 120 AC.  Around here in the country, +/- 20 vac is no big
deal, but you do have to buy special lightbulbs to get any kind of
life.  So, I guess the best way to handle these surges is a regulated
supply.  Even in industrial areas, I have watched the line voltage jump
from 108 vac to 125 vac in a matter of minutes at the end of the nominal
working day.  That's nearly as much stress as just turning the bulb on.  

Also some projector bulbs don't have much inductance, especially
halogens and calibrated, longlife tungstens.  But certainly are a number
of bulbs who could benefit from those above techniques.


> P.S. - Not to sound like a party pooper, but another way is to just have
>        a spare set of bulbs.  They don't burn out *that* quick do they?  :-)


Depending on the age of your equipment, and the equipment quality, the
cost of a bulb today can exceed the value of the equipment!!  That is a
good possible alternative to investigate.   Another is to replace the
bulb with a halogen as previously and widely discussed in this group.

I just strippped a Bruel&Kajer (Sp?) 35mm microfilm projector because
the bulbs were unobtanium.  Got two Rodenstock Ysaron lens, a 38 mm f/4
and a 75mm f/4.5 plus a the entire lens assembly for the illumination
subsystem.

Not bad pickings.

Regards, 
--
John Ohrt,  Regina, SK, Canada
johrt@xxxxxxx


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