[sdiy] Multi-Input filters

[Osamu (Sam) HOSHUYAMA]

JH and List,

jhaible wrote:
> > In this Mr. Tanaka's site, some explanations about VCFs
> > are updated.  Theories of Korg35 style filter and the
> > transistor ladder filter are added last year.  There
> > may be some other additional updates.
> >
> >   http://www.asahi-net.or.jp/~wz4k-tnk/kairo/vcf.html
> >
> 
> Awsome web site indeed!
> This gave me inspiration for my JH-720 project, and the PS-3200
> clone would not have been able without it either.
> 
> Theory of Korg35 filter: I just saw there is some new (Japanese)
> text, referring to voltages and currents in a drawing of the 2-transistor
> core.
> 
> Sam, as you're speaking Japanese and I'm not: Is there new information
> about how this actually works? (Of course the transistors act as VC
> resistors, but *how* they do this is still beyond me, and beyond
> every industrial analog ASIC designer I've asked so far. )

The 3rd box of "B: TRANSISTOR" qualitatively describes how a saturated 
transistor works as a VCR.  It includes quite detailed relationship of 
carriers and biases with a figure of Vce-Ic response:

  http://www.asahi-net.or.jp/~wz4k-tnk/kairo/vcr1.jpg

However, I'm afraid automatic translators can't do the job properly
because of indent and spaces in the page.  I tried to use a translator 
with modified indent, but I still can't understand the output english.
If you want to see the odd output, I'd send it to you off list.

Regards,
Sam Hoshuyama
-- - ---  - -- ------ - -------- -- - ---- -
Osamu (Sam) HOSHUYAMA      houshu at rogers.com
                              Ottawa, CANADA
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