Ideas for Design - self-heated transistor

[Stopp,Gene]

Neat idea about having the same transistor perform both the sensing and
the heating....

The question now becomes - "how well does this circuit apply to
synthesizer VCO's?"

It looks to me like it may be a bit of overkill for a synth VCO. Maybe
it would be good for heating several transistor pairs for a bank of
oscillators, rather than being used on a per-oscillator basis. Also, I
would be concerned about the power supply glitches that it would cause.
It's a power transistor in a TO-220 package and if you look at the
schematic, it's connected directly across +5 and ground for 10 ms every
heating cycle. Glitch city? Perhaps it wouldn't be a problem if the
circuit were installed on a little circuit board that piggy-backs on the
synth circuit board, powered by a separate +5 supply from everything
else?

The good old thermostatted 3046 seems more practical for individual
VCO's. Good web site, though. I'll make that one a bookmark!

 - Gene

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From: Roy Tate
To: 'Synth-DIY'
Subject: Ideas for Design - self-heated transistor
Date: Tuesday, February 17, 1998 1:59PM

Someone on AH mentioned this magazine, so I checked
it out on the web.

Electronic Design - "Ideas for Design"

Check out the article on the multiplexed single transistor heater...

"Self-Heated Transistor Thermo-stats
 Individual Components."

http://www.penton.com/ed/Pages/sitepage/ed_acces/0112id.htm