RE: Bending of Ohm's Law was Re: Gap Question

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Stephen Mathieson" <s.mathieson-at-charter-dot-net> 

I don't have a graph but I have heard of 2 guys that got rich by using the
nonlinear characteristics of an incandescent bulb in the feedback circuit of
an audio oscillator. They may have documented the temperature / resistance
relationship. Their names were Hewlett and Packard

Stephen A. Mathieson

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Sunday, February 29, 2004 4:47 PM
To: tesla-at-pupman-dot-com
Subject: Re: Bending of Ohm's Law was Re: Gap Question

Original poster: Ed Phillips <evp-at-pacbell-dot-net>

Tesla list wrote:
  >
  > Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net>
  >
  > ----- Original Message -----
  > From: "Tesla list" <tesla-at-pupman-dot-com>
  > To: <tesla-at-pupman-dot-com>
  > Sent: Saturday, February 28, 2004 9:10 AM
  > Subject: Re: Bending of Ohm's Law was Re: Gap Question
  >
  >  > Original poster: dave pierson <davep-at-quik-dot-com>
  >  >
  >  >
  >  > >Awesome!!
  >  > >Any idea where I could find a V I curve chart for a standard light
bulb?
  >  >
  >  >     Its a straight line.  A resistance.
  >  >     (pause...)
  >  >
  >  >     AT ANY ONE TEMPERATURE.
  >  >        (To fully plot it, or any, needs a 3D graph...
  >  >         with temp on the other axis...)
  >
  > Nope.. at a constant temperature of the bulb, a tungsten filament bulb
will
  > have a very nonlinear V/I curve (reflecting the temperature of the
  > filament).  To say that it is linear at any specific temperature of the
  > filament is pointless, since there is only one combination of V and I
that
  > will achieve that temperature, so there's no relationship to be linear or
  > nonlinear.
  >
  > yes, one could conceive of a scheme where one heats a filament by adding
  > power externally, to hold it at constant temperature, and, in fact, if
you
  > can do that, you will have a linear resistor.  Oddly, though, in
practice,
  > one measures the temperature by measuring the resistance of the filament,
  > and adjusts the power accordingly.
  > This single value behavior is what folks making precision (<0.01 dB) RF
  > measurements depend on with using thermistor probes by the DC current
  > replacement technique.

	I think constant FILAMENT temperature was what was implied there.

Ed