[sdiy] New long term project

[David Ingebretsen]

For purely nostalgic reasons (short history below if you are interested) I
want to build a Steiner-Parker Synthasystem/Synthacon clone. Nyle gave me
schematics to his modules in 74, but (long story) they are gone. I found
some Synthacon schematics which nearly fit the bill but I have some
questions.

While I can read a schematic, and I took upper level EE classes as an
undergrad and some more in grad school, I am -not- pretending to be an
analog guru.

In the schematics, the matched NPN pair (2N5172, I still have a boatload of
them and the PNP's Nyle used from when I was building an SP in 74, but alas,
no FET's) is a pair of discreet transistors which were bent over and a
thermistor stretched across the both of them. 

	1a.	Can this pair be replaced by an SSM chip? What
characteristics would be important when trying to see if I can substitute
the SSM chip? 

	1b.	Is it your experience that making this substitution will
somehow change the character of the oscillation? I hated matching transistor
pairs back then, and don't think I'll like it any better now but will do it
if it will preserve some audio quality.

	2.	Next, as I lamented, I don't have the old 2N5163 FET. I have
found some cross references, but am unsure again which parameters I need to
compare to match them. Can I just trust the cross reference charts and
blindly substitute the one recommended?

For what it's worth, this is not for profit, or sale. I just want to say I
finished what I started as a 17 year old so many years ago.

Thanks
David


***********************************
Historical note:
Nyle was my neighbor and I don't know how, but I got his name as I was
becoming interested in synthesizers. I called him and he invited me over. I
left with a fistful of schematics and was totally inspired. Over the course
of the next 9 months or so, he gave me more help, demonstrations, and even a
summer job soldering PCB's in his shop. I only ever got a VCO and keyboard
working. Life happened, I was gone for a couple of years and my brother
threw it all out, schematics and all. All I have left are a handful of pots,
and some transistors.

So, with my mid-life crisis in full gear, I am now at a point where I want
to finish the thing that really got me started. I want to build a true
Steiner-Parker synthesizer voice. VCO, VCA, VCF, EG at the least.

I don't know what I'll do with it other than look at it and feel happy :)

************************************