[sdiy] Russian parts and synth schematics...

[Jaroslaw Ziembicki]

----- Original Message -----
From: "mikas" <mikas at turbodsl.lt>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Tuesday, August 31, 2004 2:53 PM
Subject: [sdiy] Russian parts and synth schematics...


> can someone tell me if there is prototipes for russian
> chips and transistors?

Hi, Mikas and all,

Many years ago I also read the "Radio" magazine... I know Soviet
component types.
The K176 series is equivalent to the CMOS 4000 series. For example:
K176KT1 = CD4066, K176LE5 = CD4001, K176LA7 = CD4011.
KT3102 transistors can be replaced by any NPN transistors (silicon
ones of course). The transistors KT3107X you should replace by
2N3906's or other PNP *switching* transistors.
If you want, I can help you to find replacement for each part - but it
may take some days...

By the way, the VCF is variable-state, based on linearized CMOS gates
as integrators (DD8.2 and DD8.3, CD4001). For frequency controlling
serve two "switched resistors" (R52+DD9.1 and DD9.2+R54, CD4066).
There is another VCF (ru_synth_diy - 7.jpg), a Sallen-Key low pass,
either with "switched resistors". I don't know what it is for (haven't read
the text yet). Maybe it serves as a VCA.

Generally, I like the circuit. It is simple, yet full of clever solutions,
like
generating both CV and gate using a single-contact keyboard! And
only very cheap and easy-to-get components have been used.
Note: there are no opamps at all there!
Of course, there are drawbacks; for example the lin/exp converter uses
only one transistor (VT9) and is not temperature-compensated!
Anyway, Mikas, if you decide to build this synth, then I'm ready to
support you.

Regards,
Jarek