Tube Moog (Was:Re: Website update)

[Tom May]

jhaible at t-online.de (jh.) writes:

> I'm not very familiar with UJT transistors, I admit.
> What advantage do they have over the (composite) SCRs in Korg VCOs ?
>
> I haven't understood these SCRs completely either

Me either.  A few years ago I asked a question here about what kind of
temperature dependencies the Korg-style SCRs might have and I still
haven't gotten or reasoned out the answer.  I'd start by guessing that
any temperature dependencies must cancel out in the various devices,
otherwise it wouldn't be a practical VCO . . . but I don't even know
how the SCR works -- I built an MS-20 style VCO a while back but the
SCR wouldn't work when I poked it with a scope probe so it was
impossible to see what was happening.  I could spice it, I guess.

> (like: why do some BJT
> transitors
> work better than others to build such a composite SCR), but the CCO core
> taken
> from the MS-20 works so nicely in my JH-720 that I won't use anything else
> in the
> PolyModular.
> 
> JH.

fTom.