[sdiy] ETI vocoder input amps

[Hallvard Tangeraas]

At 03:05 +0200  25.10.01, Magnus Danielson wrote:

>Hej Hallvard!
>
>(This weeks lesson in Swedish - "Hej" means "Hi")

Hi there!
 long time no see. Still struggling with the vocoder as last time we
were in touch.


>> A project of mine which has been waiting to get completed for many
>> years is the ETI/Powertran vocoder.
    [.......]
>> Has anyone been able to complete this vocoder and can help out with the
>> two input amps? Alternatively, totally new input amp circuits would
>> have to be done to get the project completed.
>
>Just to complete irony, I have exactly the same problem with mine!

You haven't found the solution yet either? A real bummer this circuit.


>Just to annoy me even more, I have actually made one of them work, but
>fail to duplicate this (which is *really* ironic, since they are
>essentially identical).

Yeah, this is the really strange part.
The problem (and solution) *MUST* be in there somewhere, but knowing
how it is with myself and problems -if you mess around long enough with
these things you just get stuck and can't see the solution, even if
it's right in front of you.
I have a feeling the problem has to do with how the pots are connected
(rather strange design), but I thought we had that sorted out. Still no
luck in getting it to work though.


>The layouts lack clear signal and component positions (oh, they did in
>the article, but that was black on gray and that is just fuzzy for us now).

And there were some typos in the schematics to confuse us even more. I
believe I might still have those web pages I made with the schematics
updated which we both looked at last time.


>Now, I seem to slowly put up steam on repairing things (this evening
>is devoted to debugging the PSU of a Synthi AKS) so maybe I get that
>detail fixed eventually (I have several much more fun things to fix
>before that) and actually get that vocoder trimmed up and put into its
>place again (it has stood around here on the desk and on the floor for
>a couple of years).

My vocoder isn't nearly that completed as I haven't built the casing
yet. The pan is first to make it work, then possibly add some extra
"goodies" like an effects-processor later on.
But if I get the input amps working I believe I can wire all teh
circuit boards together and at least see if it explodes or works ;-)


>So, you where really not reading this, where you?

Huh? *this* message?
If you're referring to some past postings then no, as I've just joined
the list (re-joined? I think I used to subscribe to this list a while
back, but not for a long time now).
I've got a few projects going and thought it was about time to get
beyond the "thinking stage".


Hallvard
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