Kick Sync circuit adds hard sync at any phase to VCO or LFO

Ricko

I don't recall having seen any circuits for this around, so I thought I'd make one: The Palpitator

This is a kind of hard-synch circuit, where you select the phase that you want your wave to start at. You could use it to synch LFOs to the first beat of a bar, or for VCO synch. It works as an add-on to oscillators, rather causing any reset. (This is not the kind of synch where you say "reset my slave oscillator when the master oscillator is at a certain phase" this is the kind where you say
"When the master generates a synch pulse, advance this oscillator to the selected phase".)

In the diagram, the top is a fairly standard Electronotes VCO. (It uses a 331 comparator, so it needs a pullup resistor, if you need to use a 311 then you need something else.) We use the saw signal.

The bottom is a simple waveshaper, which converts the saw to a triangle by fullwave recitification. There is an offset selector so you can go from saw to triangle to ramp). It also smooths out glitches.

The middle section is the guts. It has a flipflop that gets set by the master oscillator or sequencer. This puts a high voltage into the frequency input of the VCO, to speed it up as much as practical. There is a variable window detect on the VCO saw, to reset the flipflop when the desired phase has been reached.

So this synchronizes by FM, not resetting the oscillator's integrator.

The values shown are for an LFO. If you wanted to use it for a VCO, you would need to adjust the glitch suppression.

PALPITATOR.JPG

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Rick Jelliffe Palpitator

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Ricko · Posted: Mon Jun 05, 2017 11:31 pm Post subject: Example

Here is an example trace from TINA-TI simulation.

If anyone builds this, please let me know.

You can see from the saw and tri traces below that this would be suitable for producing wobbles and rhythm accent variations: the tightness of a highhat, or the accent in a drumline or sequence, for example.

PALPITATOR-EG.JPG

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Example of synching saw to about 270 degrees phase of saw.

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