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Old 02-08-2009, 07:49 PM
nealbeard nealbeard is offline
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Default CV controller for frostwave resonator

Hello all.

I'm hoping to use the MPA digi pot device to create a CV controller for my Frostwave Resonator Filter.

The filter uses 10v CV inputs to control high pass and low pass resonance and frequencies.

Following Paul Perry's notes I used a 9v battery and a foot volume pedal to make a CV foot controller. Vague small pic here... it works great.

http://www.nealbeardahm.blogspot.com/

My idea is to use the digi unit pot to vary another 9v battery in the same way I used the pot inside the foot volume pedal.

Anyone else tried it? Or advice?
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Old 02-09-2009, 11:02 PM
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John John is offline
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Quote:
Originally Posted by nealbeard View Post
Hello all.

I'm hoping to use the MPA digi pot device to create a CV controller for my Frostwave Resonator Filter.

The filter uses 10v CV inputs to control high pass and low pass resonance and frequencies.

Following Paul Perry's notes I used a 9v battery and a foot volume pedal to make a CV foot controller. Vague small pic here... it works great.

http://www.nealbeardahm.blogspot.com/

My idea is to use the digi unit pot to vary another 9v battery in the same way I used the pot inside the foot volume pedal.

Anyone else tried it? Or advice?
Hi Neal, this could definitely work. My only recommendation would be to use the digipot to divide 5V from the MPA DC 5V output, and then feed that voltage (0 to 5V) into an op-amp circuit to get a larger (0 to 9V) voltage range. According to the digipot specs, only voltages up to 5V should be connected to any of the terminals--so they're not suited for dividing 9V.

Hope this makes sense--please let me know if I can provide more info.
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Old 02-10-2009, 10:13 AM
nealbeard nealbeard is offline
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Great.

Many thanks for the reply and the info.

I haven't had much experience of using op-amps but at the moment but I am using a three stages of a cd4049 ic to make a distortion box. Might this work?

Or else would you be able to recommend a suitable ic/schematic for ramping the 5v up to 9v ish range?

I have a multi-meter so i guess I can tweak a circuit to get the amplification in the right range.

:-)

Thanks

NB
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Old 02-10-2009, 09:27 PM
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Quote:
Originally Posted by nealbeard View Post
I haven't had much experience of using op-amps but at the moment but I am using a three stages of a cd4049 ic to make a distortion box. Might this work?

Or else would you be able to recommend a suitable ic/schematic for ramping the 5v up to 9v ish range?
The op amp circuit you want to build is called a "non-inverting amplifier". There are tons of examples of this on the web. It's covered in Wikipedia and lots of electronics pages.

Basically, you'll have an op amp and a couple of resistors. You'll simply select resistor values so that the "gain" is roughly 9/5. You can also substitute a potentiometer to provide a variable resistance, so that you can tweak the gain in real time. ("gain" is defined as the ratio of the circuit's output voltage to its input voltage)

I'm not familiar with all of the op amp chip #s, but you can always consult the datasheet for info.
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Old 02-14-2009, 09:32 AM
nealbeard nealbeard is offline
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great!



many thanks for your help.

NB
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