Fruit & vegetables as a CV source?

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Kaput
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Fruit & vegetables as a CV source?

Post by Kaput » Sat Aug 31, 2013 10:32 am

I know - it may sound like a joke to some, but I have just connected a potato to the pitch CV input of an oscillator.

I was reading up on 'fruit batteries' and couldn't resist trying them with the modular.

The potato has zinc and copper electrodes stuck into it. These are connected to a 1/8" standard euro jack lead, via crocodile clips. I'm getting about a volt from the potato! It's working as a CV adder to the pitch control, it's bizarre.

What happens when the electrolytes deplete? Will I get a wavering in pitch, or other oddness?

Has anyone else tried similar experiments? Tell me your findings, I'll be very interested to hear from you.
Last edited by Kaput on Sun Sep 01, 2013 4:36 am, edited 2 times in total.

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DerHeinrich
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Post by DerHeinrich » Sat Aug 31, 2013 10:44 am

It works. two friends of mine have an ongoing project called Fruitpower.
I too have participated in several of their performances with a Eurorack suitcase.
And indeed fruits do run out of power like batteries. Important: don't eat the fruit after use!
Basically all fruits work. It's fun!

These are my friends in performance

[video][/video]
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Post by ollepetersson » Sat Aug 31, 2013 10:45 am

I've seen this being done before but not with eurorack. Now give us some audio of your fruit sallad compositions :tu: . Maybe you can do some CV processing as well? And affecting it by chopping up the fruit :hihi:

/Olle

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Post by Samwise » Sat Aug 31, 2013 10:46 am

I'm getting about a volt from the potato!
Are you sure it wasn't 1.2 volts?

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Post by flx » Sat Aug 31, 2013 11:26 am

DerHeinrich wrote:Important: don't eat the fruit after use!
Why?! What happens?! You can't just post something like that and not explain the horrible things that will happen to people not following your advice! :zombie:
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Post by Kaput » Sat Aug 31, 2013 11:59 am

DerHeinrich wrote:It works. two friends of mine have an ongoing project called Fruitpower.
I too have participated in several of their performances with a Eurorack suitcase.
Great video! :tu:

I'm going around my kitchen right now, with a multi-meter, checking out different fruits and vegetables. The humble cherry tomato seems to be a winner in terms of current output so far. :hihi:

The potato I have connected to my oscillator is still generating CV, even after a couple hours in constant use. The pitch has dropped a few semitones.

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Post by Kaput » Sat Aug 31, 2013 12:01 pm

Samwise wrote: Are you sure it wasn't 1.2 volts?
According to my multi-meter, it was just under a volt from the potato. A rechargeable AA battery was giving me the expected 1.2v, though.

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Post by Kaput » Sat Aug 31, 2013 12:02 pm

ollepetersson wrote:Maybe you can do some CV processing as well? And affecting it by chopping up the fruit :hihi:
/Olle
I'll be giving this a try for sure. I was thinking of chopping up an apple and applying various slices to different CV destinations. Could be fun.

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Post by billsship » Sat Aug 31, 2013 12:04 pm

That video is great! Thanks for the idea. I've got a potato sitting on the counter. Maybe if I stick it in the oven it'll turn into an LFO!

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Post by DerHeinrich » Sat Aug 31, 2013 12:09 pm

Kaput wrote: Great video! :tu:

I'm going around my kitchen right now, with a multi-meter, checking out different fruits and vegetables. The humble cherry tomato seems to be a winner in terms of current output so far. :hihi:

The potato I have connected to my oscillator is still generating CV, even after a couple hours in constant use. The pitch has dropped a few semitones.
Thanks! I'll pass on the compliments :hihi:

The high point of some of their shows was often the cutting of a pineapple, you could hear the voltage drop with every slice being taken off :banana:
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Post by LeFreq » Sat Aug 31, 2013 12:45 pm

There's actually a lot of cool fruit-instrument uses on the 'net, from modular synths to MIDI controllers.

Cool stuff.
:tu:

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Post by anselmi » Sat Aug 31, 2013 1:30 pm

[video][/video]

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Post by wavecircle » Sat Aug 31, 2013 2:03 pm

I do this experiment at college with my students. It's all about the reactivity series. If you can replace the copper with silver or gold you should get a higher voltage output. The fruit is just a transport mechanism for the electrons.

It's an interesting experiment, it would be nice to try some group 1 metals but they don't tend to last long in moisture. Aluminium should be more reactive than zinc but it has such a high rate of oxidization it's a pain. In the context of CV though and getting something "musical", if you use polished aluminium it will start to oxidize, this results in a decreasing voltage against time. TRY IT!
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Post by Kaput » Sat Aug 31, 2013 3:53 pm

anselmi - I love that video (and nice track!).

wavecircle - Thanks for the insight. I'll try replacing the zinc with some kind of aluminium and see what I get. Very interesting stuff.

I'm wondering... if I connected loads of CV destinations to one source, would the power drain more quickly, due to the heavier load?

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Post by sduck » Sat Aug 31, 2013 8:33 pm

Point of order - you don't have to put euro in the title of this thread - this would apply to all formats. I know some of you don't realize this, but there are other formats besides euro.
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Post by jonah » Sat Aug 31, 2013 9:57 pm

I'm surprised you aren't already noticing irregularities.

-run a few in series

-will also work with wet, salted paper towels in between your electrodes. The duration has a lot to do with the moisture, with paper towels it might be easier to make them right on the verge of not working.

-you could add a capacitor to smooth it.

-can be nice noise/random source if you amplify it.

-supposedly, magnesium works as a metal. Could you crush up vitamin supplements or something?

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Post by Kaput » Sun Sep 01, 2013 4:38 am

sduck wrote:Point of order - you don't have to put euro in the title of this thread - this would apply to all formats. I know some of you don't realize this, but there are other formats besides euro.
Good point - my thread was moved from the euro forum anyway. I made it euro-centric in haste, actually - I just happened to be using it at the time and didn't think past that. :mrgreen:

I have other formats too.

Title changed. :tu:


jonah - thanks for those ideas / thoughts. I have thought about the amplification, but the paper towels idea is something I have yet to try! More experimentation today, I think.

One experiment I tried yesterday was using a small strip of kitchen foil in place of the zinc electrode. This conducted less current and was noticeably 'dirtier', giving a more unstable result. Sounded great when applied as a CV.

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Post by Dcramer » Sun Sep 01, 2013 10:35 am

So could you try passing an audio signal through a fruit? Could it function like a filter of sorts?

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Post by nrvana8775 » Mon Sep 02, 2013 10:36 pm

Ha, this is so awesome!

What other sorts of natural things produce waveshapes?

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