[sdiy] Drone Synth

[Scott Gravenhorst]

"john mahoney" <jmahoney at gate.net> wrote:
>> ...but only square waves
>
>If I recall correctly, Scott Gravenhorst has used a PLL to generate saws =
>from squares. Would that be useful?

Actually, this came from the beloved "Adolph Amin" AKA Bjorn Julin/Nillson.
 I have a simplified schematic at:

http://home1.gte.net/res0658s/electronics/4046PLL_saw_out.gif

It's a dual input high impedance amplifier connected to each side of the
VCO cap.  The outputs are summed and voila, out comes a sawtooth.

I never got around to actually trying the waveshaper because I couldn't get
the VCO to behave linear enough for use in music.  But the principal of
operation is not complex and there is no reason for it not to work.

IMHO, the 4069 VCO is the best bet, and if you eliminate the PWM part, you
can make 2 VCOs from one chip package.


>He's also worked on some kind of divider for creating different =
>intervals from a master (high speed) oscillator.
>
>The above is from memory, perhaps Scott can add some details.
>--
>john
>
>
>  ----- Original Message -----=20
>  From: Steve Allen=20
>
>
>
>  Hello All,
>   I'm looking to build a module that will be used to generate a drone =
>tone to under current the main theme in a musical pieace. I've looked at =
>using 555 timer to CD4024 divider, a dozen of those would be cool, but =
>not very flexable once tuned up.
>   How about CD4046 PLL's using the divider scheme, more flexable, but =
>only square waves. Hum....... A bank of Rene's CMOS VCO's ........ a =
>little complex but very useful.
>   Any ideas? Hope I'm not being too vague or.... well, never mind. Any =
>and all ideas will be appreciated.
>
>   Thanks,
>     Steve

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