Modulated waveform idea

[Kimmo Koli]

On Thu, 13 Mar 1997, Ken Stone wrote:

> Asuming I understand what you are saying correctly...
> The problem with this idea is as frequency increases, signal level 
> decreases if you are using fixed charge/discharge for generating your 
> waveshapes (timed for the lowest frequency). An AGC then needs to be 
> used to compensate.
 
Well, I meant by gating the signal a circuit that switches the signal on
or off in "now you the saw, now you don't"-manner. For example if you gate
a saw with a sub-osc you get a spaced saw -waveform. Consider now that the
sub-osc (=toggle flip-flop) is triggered by the moving edge of the pulse
width modulated signal. Then the window glides to a different part of the 
saw-waveform and different, voltage-controlled  waveform results.
And no fixed charging/discharging happens and no AGC is required.

> >as I was reading the posts regarding different waveforms I came up with
> >this idea for a voltage controlled waveform generator:
> >- make two sub-oscillators with flip-flops using the pulse-width modulated
> >  VCO output:
> >	- first FF is rising edge triggered
> >     - second FF is falling edge triggered
> >- these two signals are the used to gate an other waveform
> >  (saw/triangle/sine...)  on or off and the resulting waveforms are summed
> >  or subtracted and various varying waveforms results  
> >- additional variation can be added by controlling the DC-level of the
> >  signal off situation.
> >
> >All you should need is a dual CMOS FF, a 4066 and one or more opamps plus
> >the passive thuff to add two or three more pots to tweak.
> >
> >Maybe somebody has tried this already...
> 

Hope this helps,
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   Kimmo Koli                         Helsinki University of Technology 
   kimmo at ecdl.hut.fi                  Electronic Circuit Design Laboratory
   http://www.ecdl.hut.fi/~kimmo      Otakaari 5 A 
   Tel:  +358 9 451 2273              FIN-02150 Espoo
   Fax:  +358 9 451 2269              Finland 
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