Keyboard circuit (was Stretch tuning a resistor string)

[Hallgeir Helland]

Harry Bissell wrote:
> 
> The problem with the 3340 tempco out is that you have to have the 3340
> glued (thermally) to the device you want to track...
> 
> 3340 is a mighty expensive tempco, ain't it ????

Yep. ... OK -  I will explain.

The 3374 dual VCO have a temperature detector on-chip, but the 
VCOs aren't compensated. (the 3340 is internally compensated
on the expo converter.) The designers idea is that you take that
temperature detector ooutput and stick it into the reference 
input on the system DAC, thus multiplying the DAC CV output with 
the CV from the temp. detector.

I have one of these chips and I want to use it for something useful.
I thought of building a basspedal synth (ala Moog Taurus) but 
someone said a 3374 would be overkill and I agreed. I want to build
a small monosynth - but I don't bother to make a digital key scanner
and all that if I can get temperature compensation by controlling 
the current through the keyboard resistor string with the temp. 
detector output on the VCO! 

But I don't know if I'll ever get around to do it.
I am not patient enough to sit and experiment a whole lot.
I recently (today) finished a clone of the Electro Harmonix Bass
Micro Synthesizer, and that involved quite a bit of tinkering and
noodeling -- finding errors in the schematic for instance. :-)


OK sorry - Ramble mode OFF!


Hallgeir
-- 
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 Hallgeir Helland   hhelland at mailandnews.com     
    Evlogia           http://fly.to/evlogia
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