Looking for some tips, DIY controller.

[J-Jul]

Hello there,
I want to control the LFO rate more precisely, working with the EP-2 is too much of a guess.
As a newbie, I am not familiar with all the possibilities. I've looked into the MP-201, but it's hard to find one these days and I don't have the money for it (yet).

Here is my idea:
I want to build a controller (stompbox) that doubles/triples/etc the rate of the LFO of my MF-102. A stompbox with multiple switches.
What do you think is possible, and how?

I think there must be a voltage/rate formula or something.

Hope you can help me out!


Jack

[stiiiiiiive]

This must be possible.
There are some limitations though: you won't be able to go beyond the rate limits you have now on your fooger, meaning that beyond a certain value, the multiplicated value will be hitting the ceil.

[Vsyevolod]

This can be done easily with Modular Synths...

Stephen




.

[willi]

It is easier to divide down that double up. Send a square wave to 555 circuits or other timer based circuits and it will half the values. You can get chips that take a single input and output multiple progressive divisions but a 555 circuit is an way to start dividing down a clock signal. Certain simple octave-up circuits for guitars could also probably be used to double frequencies but perhaps with less precision.

555s are cheap and versatile and there are lots of example circuits available freely online. Good luck!

[willi]

The equation behind many of those circuits is the RC constant.

[yesman]

The short version is yes, you can make a voltage divider box that will
give you specific output voltages, which will control the rate of the LFO. (The range of the LFO is extended when you add external CVs to it's input - which can be negative, getting into the uber slow. But, then you will need a +/- voltage source.) You could choose a middle position as your base setting then dial in a rate with the 201's LFO pot. Then moving to positions which add to the CV (less resistance, like pushing the EP-1 pedal forward) will increase the LFO speed and switching to positions which decrease the CV (more resistance, like pulling the EP-1 pedal back) will slow the rate. It looks like about +0.7v will double the frequency. This will only work within the overall CV range of the 102, so if you are near the extremes - slow or fast with you're base setting - you may not have all the positions available. If you use trim pots (or regular pots, depending on how big you want this to be)for each position you could have a simple programmable CV box and one position can be for the EP-1 so you could still do sweeps with the pedal......