Voltage Controlled Oscillator Controlling a Phase Pedal

[YouAre]

Back Story:
I've got a Tonepad Phase 90 ( http://www.tonepad.com/getFile.asp?id=42 ) in which I would like to replace the LFO for 2 reasons. I would like to decouple the LFO from the audio path (I am experiencing ticking, and it was resolved after I put the the same LFO on a separate board and provided an isolated reference voltage), and I would like to incorporate a (modified) LERA control ( http://www.geofex.com/article_folders/lera/lera.htm ). I understand this uses a whole opamp rather than half of an opamp of the stock phase 90, but we can conceivably drop the op amp from the LERA with this new setup.

I was considering using the following circuit:
http://datasheetoo.com/amplifier/lm3403-voltage-controlled-oscillator-circuit-and-datasheet.html
http://www.falstad.com/circuit/e-vco.html

If we apply 9V to the positive input of the opamp to the right, I believe we get a 4.5V output. So we can tailor that voltage to be in the output range that we need for the Phase 90. By applying a DC voltage to the input of the VCO (you can change that in the Falstad), we can reasonably vary the frequency without too much of a variation in output voltage.

We can use 2 pots set up as voltage dividers (using resistors to pre-determine the limits of travel) and switch between them for 2 rates. If we're clever, we can use the switch/capacitor of the LERA and abandon the LDR aspect of it entirely. Explaining that will be another exercise that I'll save for later.

The question I pose now is whether or not the listed VCO can be retrofitted to serve as the oscillator for the phase 90. Does anyone see any issues with current output of the VCO/current required to drive the Phase 90's FET's? Are there any other issues that should be accounted for?

Thanks for the help, and I hope you can use this idea for a fun new project.

[duck_arse]

that 2 opamp and transistor vco appears in just about all dual and quad datasheets. I've used it before, it works as advertised. without comparing part for part values, I would say if the output of this is not the same as the output from the standard integrator/schmitt osc, it can be easily tailored to match.

throw it on the breadboard, give it a whirl.

[R.G.]

It probably works well.

It uses the same VCO as the one in this ramp up/down sweep oscillator for a phase 90: http://geofex.com/FX_images/p90ramp.pdf

[YouAre]

It probably works well.

It uses the same VCO as the one in this ramp up/down sweep oscillator for a phase 90: http://geofex.com/FX_images/p90ramp.pdf

I literally just found this earlier this morning...Palm. Meet forehead.

[YouAre]

that 2 opamp and transistor vco appears in just about all dual and quad datasheets. I've used it before, it works as advertised. without comparing part for part values, I would say if the output of this is not the same as the output from the standard integrator/schmitt osc, it can be easily tailored to match.

throw it on the breadboard, give it a whirl.

I was asking because I've ordered the comparator chip, but don't have one yet. I simulated it last night (it'll work with an ideal opamp of course), and it can definitely be tailored to match the phase 90. Particularly if you adjust the cap value (10n is waaaay too small), match the reference voltage (5.1v), aaaand mess with the voltage divider going to positive pin to get a symmetrical waveform.

I was initially wondering why VCO's aren't used more often as LFO's in pedal, to eliminate the need for reverse alpha pots. I realized that it's quite a bit of extra parts.