90-degree phase tri lfo revisited

[Rene Schmitz]

Hello all,

I did work out a circuit which can do a voltage controlled phase shifted
triangle from a saw. One can connect this circuit to a 
LFO (VCO) which already has a (fwr) triangle convertor and then at 0V for
the phase input you have 90deg shift between them. The phase 
is variable from 0-180deg between those two outputs.
I have not yet build it but I don't see a reason why it 
shouldn't work. 

Bye
 René


>Pretty much.  The EN design (app note 73?) was for sawtooth and CV in
>the range 0-5V, I built a similar circuit but for sawtooth and CV in
>the range +/-5V.  Put the following through a summer with 100K in the
>feedback loop using the specified input resistors to get things
>weighted right.  Or use whatever resistor values you want but keep the
>ratios.
>
>1. Inverted sawtooth (100K).
>
>2. Output from a comparator with + input connected to the non-inverted
>   sawtooth and the - input connected to the CV (slightly less than 300K
>   to compensate for the fact that the output is not rail-to-rail,
>   I used a 270K + 50K single-turn trim which measured out to 296K
>   with a TL082 for a comparator).
>
>3. The CV (100K).
>
>4. (Optional) some kind of additional offset voltage to adjust
>   for the fact that the comparator probably doesn't have symmetric
>   output levels.  This will keep things symmetric about zero volts.
>
>fTom.
>
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