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Author Topic: Digital Potentiometer Problem involving Guitar Pedals  (Read 293 times)
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Hi there, I'm relatively new to Arduino so let me know if you need more detail:

Aim:
-To digitally control analogue guitar pedals (DIY ones I've made- powered by 9V battery) with Arduino

- Using digital potentiometer to 'mimic' or track the movements of mechanical potentiometers in the circuits in the hope of eventually storing and loading preset values to the output. Is this possible??

I understand that digital pots can use buttons or other inputs to determine the resistance levels required. I will need them to receive the output voltage from a volume control of the circuit, max is around 2.55V. Eventually store the value as a preset and output it back into the circuit on command (I'm assuming a DAC would be needed?)

At the moment i'm hoping to use a MCP4131-104 SPI digital pot http://ww1.microchip.com/downloads/en/DeviceDoc/22060b.pdf

Circuit example:
V7C Big Muff using 100k volume pot for tracking movements: http://www.bigmuffpage.com/Big_Muff_Pi_versions_schematics_part3.html


If someone could explain their thought process to break down the stages for me I would be immensely grateful.

Thanks,
James
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http://www.maximintegrated.com/app-notes/index.mvp/id/1828
and
http://www.maximintegrated.com/app-notes/index.mvp/id/3077
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Thanks for the links. They are very helpful although I am still a little confused as I want to be able to set a voltage from 0-2.55V (out of my circuit). So I have my digital potentiometer hooked up like a mechanical potentiometer with PoW(Wiper) connected to the output guitar jack. PoB connected to the output of the circuit which with a 100k mech pot can produce 0-2.55V. And PoA to Ground.

All digital potentiometer tutorials i've seen have the two ends of the pot to 5V and Ground, with the wiper sending out a voltage in-between. Whereas my project requires a max voltage from the circuit being approximately 2.55V.

The digital potentiometer is an MCP4131 100k SPI pot. In regard to the coding i believe it should be very simple as only a command byte and a value needs to be sent but perhaps it is more difficult than I think.

It would be great to get some guidance. Let me know if I should explain things better

James
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