Expo conv. heater (tomg et al.)

[Steve Varner]

Hmmm.... maybe I should build a 19" rack-mount toaster and put the VCO
inside  ;-)
Seriously, I think I'll build a simple thermostat circuit, keep the
temperature at a sort of Death Valley level (120F), and put a slab of
styrofoam around the 3046. Would adding a separate power line from the power
bus, with separate traces on the PCB, help in solving fluctuation problems on
the VCO circuit? I don't think I want to use the pumps or Peltier things. I'm
not so sure I'm clear on the glass of distilled water test either  :-)

I'm a physics / chemistry person and so I'm not sure on the definitions of
some of the electronic terms you guys used. I don't want an entire
electronics coarse...just some clarification. I'm sure some of the other
folks out there are as lost as I am.
What do you mean by:
regulation loop
temperature loop and overshoot
SOA
migration and junction degradation
second breakdown

SV

----------------------------------------------------
Tony Clark wrote:

> > I had five small pumps on a heatsink to keep my drinks cool in the
> > summer. Now what would be rather good is to build one onto the substrate
> > in an integrated VCO. Tony Clark was going to do some small VCO
> > hybrids... perhaps this is the answer to drifting:-)
>
>    Well I wasn't working with heaters though!  I wasn't happy with the
> current consumption (which everyone knows about) nor the stability of the
> whole temperature circuit in general.  So instead I tried different
> current mirror schemes to see if any of them were more temperature
> resistant.
>    The idea was when I "discovered" that heating one side or the other of
> the mirror caused either an up or a down shift in frequency.  So in my
> limited knowledge, it seemd that if you added more transistors to the
> side that made the frequency go opposite of its normal drift (normally
> the frequency rises, I believe, so you'd add (in parallel) a few more
> transistors to the side that would decrease it) it'd balance out.  But it
> doesn't.  It seems to just shift the frequency point where the drift goes
> from positive to negative.
>    BTW, when I did my temperature tests, I used a small toaster oven and
> put the whole circuit board inside.  The oven had holes drilled in it to
> place thermometers inside so that the temperature could be measured
> accurately (those ovens are hard to heat up slow!).
>    Anyway, I won't even begin to try correlating anything with math.
> Someone else can do it.  :)
>    I will most likely try Rene's method again and see if I have better
> luck.
>
>    Tony
>
> ------------------------------------,----------------------------------
> I can't drive (my Moog) 55!         |     The E-Music DIY Archive
> ------------------------------------|
> Tony Clark -- clark at andrews.edu     | aupe.phys.andrews.edu/diy_archive
> http://aupe.phys.andrews.edu/~clark |     Contributions welcomed!
> ------------------------------------'----------------------------------