PLL possible?

hey people, do you think it is possible to build a phase locked loop custom unit on the UI level?
i thought maybe using @Joe’s compare unit but then realized a comparator needs two signals to compare one against the other… i was following the diagram shown on the a-196 doepfer pll manual…

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even if it’s not a pll it sounds like another chaotic generator, you can test it here:
Fake pll.lua (16.3 KB)

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this is how it sounds:

all parameters have been wiggled realtime. at the end i add some reverb.
overall a nice noisebox even if it’s not a pll.

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I’ve been wondering about a PLL also. I think that will get me closer to pitch tracking (?). Looking forward to checking out what you put together!

no pll at all here :slight_smile:
i thought the compare unit could compare two signals (phase or frequency) but it is instead a unit that compares the input voltage with threshold and spit out a gate, a trigger or a toggle when the input voltage exceeds the threshold. (very useful nonetheless!!!)

ah!!! while i’m writing an idea just sprang in my mind!!! if we put an oscillator or an external source to modulate the threshold signal we can maybe compare two signals! @Joe what do you think?
i will try this now! maybe that’s the key to something similar to pll!!!

EUREKA! it somehow works!!!
not able to make it track as i want right now, but as i change the frequency of my external vco it changes the frequency of the internal (square) vco! yeeeeeeah!!!

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ok, pardon my ignorance, i think i totally misunderstood the role of the comparator in a pll.
it has to be a phase comparator while what i was doing was basically trying to have a signal determining the frequency of a square wave vco. using joe’s compare unit i put a square vco in the input and modulate the threshold with an external signal. whenever the input goes above the threshold the comparator fires a gate. so in a way they are still compared but not the same way a pll works…have a lot to study here :slight_smile:
i read that the simplest phase comparator is a XOR. i’ll try with mixers and vca and stuff. will report back further discoveries.

Ok, this time i’m getting close. i followed @Joe’s ideas for motion sensor (mixing a signal with a delayed inverted copy of itself, did it for both the input and the VCO, then compared those two with the Compare unit).
i think now we are near. i can have the vco track the external signal in a significant way but the range is not too extended.
i will be away for a couple of weeks, so i have tu suspend researches but i leave the new one here if you want to test it.
if anybody can confirm that my method is correct or tell me where and why it isn’t i’d be infinitely grateful.

cannot stress how much i love this building environment, @odevices your creature is really opening my mind like few things!
here the controls:

  • in: feed it an external signal or insert another vco, sampler, whatever you want here

  • div: frequency divider for the vco frequency control

  • pw: pulse width of the vco

  • cutoff: frequency of the low pass filter put after the compare process and before the linear frequency modulation of the vco

  • q: resonance of the low pass filter put after the compare process and before the linear frequency modulation of the vco

here the new pll unit:
Hy Pll.lua (22.2 KB)

here a test, making it track my voice! left channel: pll, right channel: voice.