CA3046 replacement ?

[mbartkow at ET.PUT.Poznan.PL]

Martin Czech <martin.czech at intermetall.de> wrote:

> :::Paul -- Could you explain in further detail the failings as you see them in the
> :::3046 transistors? I am considering a replacement transistor pair with a strap-on
> :::heater.
> :::
> 
> I think it was not Paul but me...  Well, beta is low, and rbe is too
> high. This simply means bad tracking, bad exponential scale. Remember that
> our expo circuits require ideal transistors. I have seen E.N. designs
> that use extra circuitry to compensate for that.  The leakage currents
> should also be quite high.  The spec shows large sigma of the parameter
> distribution, so perhaps some chips will not work even with compensation

One thing yet:

Did anybody consider exploiting the fifth transistor for some compensation
of these effects ? If I remember correctly there was some nice trick in
the Rick Jansen's drawing of expo converter for his Moog VCF.

mb


--

Maciej Bartkowiak, PhD
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