AW: VCO-1C

[tomg]

On 03-Jan-99, jhaible wrote:
>> Super simple 4 tranny unijunction VCO. May be the worlds
>> smallest descret 1V/OCT VCO. Works a lot better than it looks.
>> 
>> http://www.mindspring.com/~vco/misc/pics/vco1c_sd.gif

>I normally have mixed feelings about such minimal circuits: They are
>tempting in their minimalistic elegance, but when you consider the
>price of one single potentiometer of decent quality, there is not much
>benefit from such low cost circuits anymore.

>Normally, that is. But I wouldn't write this mail just to word this caveat.
>Because I have found one reason to look at minimum parts count VCOs
>meanwhile: That's for building a full polyphonic "ensemble" type keyboard
>without divide-down circuitry, but with a lot of VCOs instead.

[snip]

>And last, not least: How temperature stable is your UJT VCO, Tom ?
>(not asking about the expo converter, which is a low end compromise
>no doubt - but the mere UJT / capacitor pair ?) And how does it perform
>in comparison with a thyristor solution (like Korg) ?

>JH.

I OTOH love minimal stuff and think this is neet! Sort of a
novelty circuit. Killer at the low end. rattles the rafters!

Would be great for a SHF vco to divide and shape. A micro-synth
two vco thing wouldn't be too bad. Also good as a single voice 
bass bomber! 

If you did the proper things to it I think it would be fine.
Like a pnp pair, 1K temco, poly cap, sealed trimmers ect...
However that would cost you a fortune.

Like it is NO WAY!... This thing blows with the wind. A bank
of 36/48 of these things would drive you nuts. Best to re-think
that divide-down idea.

-tg