[sdiy] moog high pass flter

[Tim Ressel]

Hi Y'all,

If I recall rightly, the Moog matching circuit is a
constant current source that attaches to the
transistor to be measured. Then the Vbe is taken. Why
not to this: Redo the circuit to produce two equal
currents and run two transistors side-by-sde. Clip the
trannies together with a wooden clothes pin for
temperature tracking. Measure the difference in Vbe
with a center-zero voltmeter.

Would that turn it into a two-brewski effort??

--tr


--- Seb Francis <seb at is-uk.com> wrote:
> Isn't this where the sixpack comes in?  If you keep
> the beer at the same temperature (and I know
> Australians are very particular about the
> temperature of their beer) this helps stabilise the
> temperature of your fingertips, and hence the
> transistors ;-)
> 
> 
> jhaible at debitel.net wrote:
> 
> > > i find matching tranies not so hard, but time
> consuming. the type of thing
> > > done drinking a sixpack and watching a movie
> (well thats what i was doing
> > > when i built the lowpass)
> >
> > ... as long as you don't stir the air too much
> when you're reaching for
> > your sixpack. (;->)
> >
> > Seriously: the temperature is crucial if you match
> transistors.
> > If you read the same Vbe on the meter, but your
> transistors have
> > a temperature difference of a few degrees C, you
> have no matched
> > transistors.
> >
> > (Not saying that you don't know how to do it. Just
> in general,
> > I wonder how many "hand matched transitors" are
> really matched.)
> >
> > JH.
> >
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> > debitel.net Webmail
> 
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> 


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