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December 22, 2014, 06:47:18 PM
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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  CV pedal 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: CV pedal  (Read 1471 times)
nosamiam
Posts: 304


CV pedal
« on: March 13, 2006, 08:37:44 PM »

Hi,
I'm planning on starting a pedal-version of this LowPass Filter:
http://www.musicfromouterspace.com/analogsynth/vcf.html

On the board are 2 pads marked "CV in."  Am I right in assuming this refers to Control Voltage?  I know in the synth world this would refer to voltage generated in response to pressing a key.  Can I somehow use a pedal for it?  Would this be a volume pedal?  And if so how would I wire the jack.  Basically I'm asking, are CV and expression pedals interchangeable?

Thanks
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mistercooper
Posts: 9


Re: CV pedal
« Reply #1 on: March 13, 2006, 09:47:40 PM »

The CV pad is indeed for a control voltage.  In this case, the voltage will control the cutoff frequency of the filter.

You could do a number of things with this in a pedal sense.  The first that comes to mind is integrate an LFO circuit that outputs a CV (Ray has several of those on his site, too).  Otherwise you could add an auxilary jack on the enclosure for the CV and use something like a ribbon controller to control it in realtime.  One of the most fundamental problems you will face is fitting all of this in a hammond  Wink

BTW, long time lurker, first time poster.  I like it here.
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Paul Perry (Frostwave)
Posts: 7470

Paul P.


Re: CV pedal
« Reply #2 on: March 14, 2006, 05:57:44 AM »

There is a terrible lot of confusion about CV and expression pedals, because different manufacturers mean different things by the same names.
A "CV" input SHOULD mean, control voltage, and you would hope that it just means, put a varying voltage here (eg from a pot across a battery, or from a LFO in an analog synth).
BUT, not always so!! Sometimes it means, connect a tip/ring/sleeve plug here & go to a pot in a rocker pedal, so the unit being controlled sends out (say) 10V and the pot in the rockler pedal sends back 0 to 10.
OR, it could be that you have a mono plug connecting, and the pot is wired as a varying resistor.

Ray's one is expecting a genuine voltage.
I expect a 9v battey across a pot (anywhere from 10K to a 100K pot), preferably linear pot, would do fine.
Just run the voltage from the wiper arm. If the pedal seems to go the 'wrong way', reverse the battery.
To vary range, chang ethe resistor on ray's filter where the CV goes in.
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bwanasonic
Posts: 2141


Kerry M


WWW
Re: CV pedal
« Reply #3 on: May 28, 2006, 12:36:11 PM »

I expect a 9v battey across a pot (anywhere from 10K to a 100K pot), preferably linear pot, would do fine.
Just run the voltage from the wiper arm. If the pedal seems to go the 'wrong way', reverse the battery.

I have tried this with an ancient Vox volume pedal, and it worked. What I am wondering is, would I be able to hook up a DC jack and run it from a PS? Any additional circuitry needed for this?

Thanks
Kerry M
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Paul Perry (Frostwave)
Posts: 7470

Paul P.


Re: CV pedal
« Reply #4 on: May 29, 2006, 06:34:18 PM »

Kerry, by all means run it from a DC wart.
The worst that can happen, is that there may be some AC ripple on the DC & this will sweep the filter a bit. BUT!!!! sometimes a lot of AC going into the filter sounds GOOD!!
So my advice is "suck it and see". I think you will be happy.
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bwanasonic
Posts: 2141


Kerry M


WWW
Re: CV pedal
« Reply #5 on: May 29, 2006, 08:31:03 PM »

Kerry, by all means run it from a DC wart.
The worst that can happen, is that there may be some AC ripple on the DC & this will sweep the filter a bit. BUT!!!! sometimes a lot of AC going into the filter sounds GOOD!!
So my advice is "suck it and see". I think you will be happy.

Wired up a noisy Ernie Ball volume pedal with a battery yesterday, and will try putting in a DC jack in at some point. Have a dummy plug for the input that I'm using as an on/off switch for the battery. I'm using it to control the Blue Ringer BTW. I can go go from subtle trem, to insect apocalypse sounds with a sweep of the treadle.

Kerry M
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