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I'm making a digital synth for a project and I need to wire in an Arduino-controlled volume circuit.

Right now I'm outputting a 0-5V audio signal and cutting it down to a pure AC 0.5V signal with a voltage divider (1kohms and 10ohms) and a capacitor. I would like to tack on a digital potentiometer to this circuit to control the audio volume so I bought a DS1807.

The datasheet is here but I'm still not totally sure how to use this -- it refers to the resistor settings in db rather than ohms, but it feels like I should be putting in a second resistor to form a voltage divider with it. What should that resistor value be? I don't see a reference to what the actual resistance of the DS1807 varies between. Or am I thinking about this circuit completely wrong?

(p.s., the speaker we'll use is a powered computer speaker)

Here's the circuit I was thinking of-- is that correct and how do I choose R3?

Thanks!

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ The potentiometer global resistance is said to be about 45KΩ so there's no need for the additional dividing resistance (100KΩ), as @meakcey writes. \$\endgroup\$ – user59864 Aug 23 '15 at 19:25
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You dont need additional resistor. Just wire audio signals to digital pot pins H0-L0 or H1-L1. W0 or W1 will give you divided signal. Pot values are indicated in datasheet page 10.

Also be carefull not to avoid recomended limits again indicated on page 10.

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  • \$\begingroup\$ oh, duh, because there's now a resistor on the left and right side of the wiper! so I put the audio signal on H0 and ground on L0 then? \$\endgroup\$ – user358829 Aug 23 '15 at 19:17
  • \$\begingroup\$ yes. you could think it as normal potentiometer. also i you could find code related link hackaday.com/2009/02/16/… \$\endgroup\$ – meakcey Aug 23 '15 at 19:18
  • \$\begingroup\$ i didn't see "then?" =) between W0 and L0 pin, you would get what you gave with i2c interface \$\endgroup\$ – meakcey Aug 23 '15 at 19:25

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