[sdiy] cheap sine wave osc

[Derek Holzer]

Hi Scott,

Scott Gravenhorst wrote:

> How accurate must the sine be?  

Fairly accurate, if one is to properly do 64+ voice additive synthesis. 
But for now, not too accurate ;-)

> There's the ICL8038.  

Of course, a function generator is easiest, but not cheapest. The 8038 
runs around EUR 5 (my estimate, not precise figure) each in Germany, so 
for 64 voices were talking something like EUR 320!!! Way out of the 
budget for a single use installation!

> I did another one with a sawtooth oscillator using a 4069UB and a wave
> shaper using (I think) 2 more 4xxx ICs

I also thought about waveshaping a saw or square down to sinusoidal. 
I'll look into it more, but I'm hoping to keep the parts count down. And 
waveshaped/filtered saws/squares could get very muddy when added 
together on such a large scale.

Tom Farrand sent me a cute little Wein Bridge Oscillator circuit using 
an LM107 and a light bulb (!!!) that he claims is the cheapest sine wave 
you can get (4 for a dollar!) with 0.008% distortion. Looks like it came 
straight from the datasheet, in case anyone else wants to have a look.

best,
d.

-- 
derek holzer ::: http://www.umatic.nl ::: http://blog.myspace.com/macumbista
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