[sdiy] New schematics

[jhaible at debitel.net]

Nice stuff, as always!

Two circuits have caught my interest in particular:

>  - New style filter (with smooth asymmetrical distortion) :
>    http://www5b.biglobe.ne.jp/~houshu/synth/VcfCtp0211.gif

This looks promising - smooth assymetrical clipping, with each
following stage dealing with the opposite half wave than the
previous one, I presume? 


>  - A method to increase the input dynamic range:
>    http://www5b.biglobe.ne.jp/~houshu/synth/Vca0302.gif

I once thought about adding a long diode string to each emitter
of a differential pair. But I've never really tried it.
Your circuit should increase the SNR by 3dB (double signal
amplitude, SQRT(2)* noise ). 
EMS built voltage controlled resistors from 20 diodes in series
(instead of 2, so the factor is 10, not 20), - that would be 10dB
SNR improovement.
Would this be possible with a differential pair, too?
Or would it be better to connect all the transistors in _parallel_,
rather than in series? (Which is what the expensive low noise
matched pairs from NS do) ?

JH.


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