Digital control of analog pedals

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Hi all,

I'm a music student with some electronics background and I'm interested
in controlling guitar pedals via a computer. Ideally, I'd like to build
some class of a midi interface which would allow me to automate the
amount of effect I require from each box.

An example of three pedals I'm interested in are as follows -

http://www.diystompboxes.com/pedals/ratmod.gif
http://www.geocities.com/SunsetStrip/Underground/8475/schematics/bigmuffmod.gif
http://www.geocities.com/j4_student/crybaby.gif

Eventually I'd like to try a whole range of different pedals as
available here -

http://www.diystompboxes.com/pedals/

Control in stomp boxes seems to be achieved exclusively via pots as far
as I can see (and switches I guess), therefore I was thinking that a
digital POT would allow me to achieve what I'm after. When I was
younger I built a circuit that used Microlan ADCs and switches and I've
just discovered that they also do 100kOhm Digitals POTS -

http://para.maxim-ic.com/Default_1WireDigitalPotentiometers.htm

Most stompboxes seem to use 100kOhm POTs but if I need more that
100kOhms I could simply cascade a number of them together. If I need
less then I simply use less. The Microlan POT is

Anyway, the next step would be to establish how I would go about
building a midi interface, suitable for use with MIDI based software,
which would drive my 1-wire Lan and which would interface to a PC via
usb. But right now I'm interested in knowing if you guys think my
approach is a good one and if you have any other ideas or suggestions
which might be useful to me.

Thanks for your help,

Barry.

 

[Walter Harley]

[...]
Control in stomp boxes seems to be achieved exclusively via pots as far
as I can see (and switches I guess), therefore I was thinking that a
digital POT would allow me to achieve what I'm after.

Seems like a good approach. Make sure you use one that can handle the
typical 9V supplies (actually often a bit higher, if powered from an AC
adapter); signal excursion may or may not be that high.

And look out for "zipper noise" when changing pot settings while signal is
present. Some digital pots are more prone to this than others, apparently.

I built a circuit that used Microlan ADCs and switches and I've
just discovered that they also do 100kOhm Digitals POTS -

http://para.maxim-ic.com/Default_1WireDigitalPotentiometers.htm

Most stompboxes seem to use 100kOhm POTs but if I need more that
100kOhms I could simply cascade a number of them together. If I need
less then I simply use less.

There are a number of manufacturers making digital pots - you might want to
do a bit of hunting around before you settle on one in particular. Google
is your friend.