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Re: [vox-tech] [no linux] High voltage circuits?
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Re: [vox-tech] [no linux] High voltage circuits?

  • Subject: Re: [vox-tech] [no linux] High voltage circuits?
  • From: Peter Jay Salzman <p@dirac.orMAPSg>
  • Date: Tue, 20 Mar 2001 08:58:32 -0800
  • References: Pine.GSO.4.21.0103200001001.21309-100000@runner.ucdavis.edu
  • References: 3AB78B26.6098A42D@acm.org


that makes total sense -- an increase in kinetic motion causes an increase in
resistivity of the filament.

i think adding a small inductance would also work, and has the benefit of not
drawing power from your source.  the "back EMF" would kick in only when the
current initially flows (and stops).


On Tue 20 Mar 01,  8:53 AM, Jeff DeFay said: 
> Mark,
> If you are using incandescent light bulbs, your current will be much higher
> during the
> brief time that the filaments are cold.  The 60 watt power consumption is
> calculated
> with the filaments at normal operating temperature;  introducing resistance
> into the circuit
> would also keep the effective resistance of the filament low by preventing it
> from reaching
> normal temperatures.
> Regards,
> Jeff DeFay
> "Mark K. Kim" wrote:
> > Anybody here ever work with high voltage circuits?  I'm creating a
> > low-volage / high-voltage hybrid circuit for the first time; a digital
> > circuit (low voltage, 5DCV) controls the logic portion, and uses two
> > relays to control two light-bulbs (high voltage, 110ACV). And I'm
> > wondering:
> >
> >    1. How much current usually goes through those 60W light bulbs?
> >       How much current is required to make it look bright enough?
> >
> >       My guess would be:
> >
> >          110ACV * I = 60W
> >          => I = 0.55A (max)
> >
> >       And I'm using a 1A relay rated at 120ACV, so my guess would be
> >       that I can hook up this relay to the light bulbs directly.
> >       But when I did that, once the light bulbs were turned on,
> >       they stayed turned on (I couldn't turn off the relay connection
> >       -- apparently the connections got fused together.)
> >
> >    2. So my idea was to force-limit the current.  I got new relays
> >       (same kind) and bought 1W resistors (200 Ohms... actually, two 100
> >       Ohm resistors soldered together.)  Once I got them in circuit,
> >       it had two problems:
> >
> >       a. The light bulbs were too dark, and too slow to lighten up.
> >          Apparently too much resistance?
> >
> >       b. I started seeing smokes come out around the resistors.
> >          I don't know if this is because the resistors need to be
> >          higher wattage, or if the current is melting the solder.
> >          I'm pretty sure the electrical wires are good enough for
> >          this project (it's rated at 700V), although if the solder
> >          is melting (meaning it's at least 400 degrees Ferenheit)
> >          then it could be also melting the electrical tape.
> >          Ideas?
> >
> > I need to know if I need to switch to higher rated relays, and if so, to
> > what.  Also I need to know if I need to use a different resistor and/or do
> > not use solder.  I'd really appreciate any suggestions from anyone
> > knowledgeable in this field.  Thanks!
> >
> > -Mark
> >
> > PS: I know this is off-topic but I figured someone here might know.
> > Besides, we've been quiet on this list for a while.  Also, this circuit is
> > for LUGOD anyway.
> >
> > ---
> > Mark K. Kim
> > http://www.cbreak.org/mark/
> > PGP key available upon request.
> --
> Jeff DeFay
> jfdefay@acm.org
> (530)753-0774

"Coffee... I've conquered the Borg on coffee!"               p@dirac.org
       -- Kathryn Janeway on the virtues of coffee           www.dirac.org/p

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