Re: Light Bulb Experiment (ala Brent Turner)

• To: tesla-at-pupman-dot-com
• Subject: Re: Light Bulb Experiment (ala Brent Turner)
• From: Jim Fosse <jim.fosse-at-bdt-dot-com>
• Date: Sat, 21 Sep 1996 20:20:25 GMT

>Date: Fri, 20 Sep 1996 01:47:33 -0700
>From: open_minded <bturner-at-apc-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Re: Light Bulb Experiment (ala Brent Turner)
>

>I *remember* that incandescent lamps have negative-resistance
>characteristics, but I could be wrong. I do recall that the negative
>resistance change is one reason why a lamp is used in a Wein-bridge
>oscillator though.
>

Sorry Brent,
	Tungsten has a very strong positive temp. coefficient. It's
this strong increase in resistance with temperature (power) that is
used to stabilize the loop gain of a Wein bridge oscillator at 1.
This prevents the oscillation from growing in magnitude and distorting
the output sine wave as the amplifier exceeds it's linear range.

	jim

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