Magnus freq doubler.Oscillator beating!

[Bjorn Julin]

Hi.

>Well, my sawtooth phase shifter is a 360 degree phase shifter, or at >least 
>very close to 360 degree... just vary the comparator voltage >over the full 
>sawtooth voltage and the comparator drops out the PWM >wave and the summing 
>network will do the rest. Maybe it is time for
>me to make a schematic of that and put up along the others?

Ahhhrg,sorry again, what i ment was that, it actually does 360 degrees, My 
design is a 0 to 5 volt cirquit,i have just been sitting to long and looking 
at the upp half of the waves on my scope, i
forgot the down phase, Forget my hassle text! What i allso ment
was the phase modulating "end result" by using frequency doubling,
the viIibBbRrRrAaAtoo effect!

>Ah, but the thing is that the whole thing is balanced!
>I get a DC error which I adjust by the resistor to negative feed. >Also, 
>this is an ugly thing since I assume the saw to go from -5 V to >+5 V as 
>well as assuming the powerlines to be at +/- 15V. That is the >ugly side of 
>it. Removing the diode so that I get a (fairly) balanced >output from the 
>comparator also removes the DC error from that signal, so then I can remove 
>the DC correction. I actually spent part >of my efforts just to ensure that 
>I still had
>DC offset at 0V!

For a single know device it should be so, but i was more reffering
to offset voltages and how close the op amp device can swing the output to 
its both rails.

The chroma uses a different aproach, they just sums up the saw
the square and the cv thuru weighted resistors (as currents tru a  4052) to 
do the phase shifts, so the second OP acts as a mixer who then passes the 
signal to a VCA.

>When Jörgen took the doubler schematic and turned it into a phase >shifter 
>based on my hints he realized this and things became even >simpler.

Actually, the whole idea with the phase shifter is that if the cv
is sweept by a LFO it simulates the beating between TWO sawtoth
oscillators.Anything from controlled slow beating into chorus/detune
sound is produced, exactly one of the nice things with the Chroma.

> > Why not using a three way switch?
>
>Uhm, I am not sure that I know how it would help... ah well..

Just to switch between uni and bi polarities, nothing else.

BJ
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