Elektor Formant Modular

Hi,

In case of Formant LFO, there's a clean and direct way for a linear voltage control mod. 
Referring to the original schema, A3 serves as a comparator, outputting +VDD and -VDD in alternation. These voltages serve as control voltages to deliver a current for integrator IC1 through P1.

So all to do is to supply an external control voltage, +CVext, invert it with an Op-Amp to create -CVext .
Then add a mux which is controlled by the comparator output and 
switches either +CVext or -CVext to P1. And you've got a linear controlled VC-LFO.

Good Luck.

--- In ElektorFormant@yahoogroups.com, "abcceihgfosdjgooenje"  wrote:
>
> Hi everyone. Is there any easy way of adding cv to the freq of the LFOs in the formant?
> Thanks:)
>