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

["Mark K. Kim" <mkkim@ucMAPSdavis.edu>]

Awesome -- that's really good to know.  Thank you!

Pete -- Adding an inductor sounds good.  What rating should I use?  (it's
been a while since I've worked with inductors :)

-Mark

On Tue, 20 Mar 2001, Jeff DeFay wrote:

> 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
> 
> 
> 

---
Mark K. Kim
http://www.cbreak.org/mark/
PGP key available upon request.