[sdiy] CMOS Saw to Triangle Waveshaper (corrected URL)

[Scott Gravenhorst]

=?iso-8859-1?Q?Ren=E9?= Schmitz <uzs159 at uni-bonn.de> wrote:
>At 07:49 04.11.01, Scott Gravenhorst wrote:
>>Heh heh, you guys!
>>
>>I'm getting there.  I did think about that, but I drew
>>it with opamps before I thought of it.  In fact, the 
>>LFO is the only part not yet built.  I know I can make
>>a sawtooth this way, but tri ... ?  With 3 inverter gates?
>>Hmm.  The integrator is easy I think.  The schmitt trigger?
>>2 gates setup as linear inverters connected together makes
>>a noninverting gain stage, then some positive feedback
>>in that system?  I'll play around, perhaps today.  I
>>*am* trying to keep this as much CMOS as possible, so that
>>would be a good use of those gates.
>
>Look at the VCO core. There is such a schmitt already. Triangle would 
>mean to change the discharge diode to a resistor, and ommit the current sink.
>(And also ommit the Franco resistor and the Diode at the cap.)
>However, the generated triangle would sit on Ub/2, 

True, and it does, but we also level shift an LFO that works
around zero sometimes.  So a level shift pot could be added to 
put it where you want it.  Maybe need a transistor or an opamp
to help there.  The LFO configuration I built interfaces
perfectly with your PWM circuit.

>and the CCW-end of frequency 
>pot in the LFO would need to be referenced to that voltage instead 
>of GND. Unless one fiddles with the supplies. One could power them from 
>+5/-5V or so to make that easier.
>
>>And then there's the 2 analog switches and the flipflop...
>>Actually, the flipflip's clock has a shcmitt trigger input.
>>I wonder if there's a way to use the JK in an LFO somehow.  
>
>I'd rather make a dual VCO and use up the other half of the waveshaper ICs.

That's a good idea.  The LFO can be made a dual then, in one
4069 package.

=========================================================  
- Government: The other religion.
- The media's credibility should always be questioned.
- Lambs who lie down with lions are lunch.

-- Scott Gravenhorst | LegoManiac / Lego Trains / RIS 1.5
-- Linux Rex         | RedWebMail by RedStarWare
-- FatMan: home1.GTE.NET/res0658s/TekLab_FatMan_WebSite/index.html