Digital Potentiometer Help Needed

[LiquidMetal]

Hello,

I am looking to build a simple volume pedal (250k) using an Arduino-controlled digital potentiometer. I found a couple of 250k digital pots, but none of them is available in a DIP package. The closest value in a DIP package is Microchip Technology MCP41100 (100k, 256 taps).

My first attempt was using a LED-LDR couple (Vactrol), but after some reading found that a digital pot would be a much better match.

Any advice how to find a non-SMD 250k digital pot or how to use a 100k in that situation will be greatly appreciated.

Thanks

[R.G.]

A good buffer before and after any expression pedal, not only a digi-pot one, is a good idea. It has the side effect of removing any significant dependency on the pot's actual value as long as it's above about 10K.

[amptramp]

You could use the circuit of Figure 9 here:

http://www.ti.com/lit/ds/symlink/dac0808.pdf

This entire article shows how to use a multiplying DAC like the DAC0808 (8-bit) as a programmable gain amplifier as well as a digital filter, programmable sinewave oscillator, pulse-width modulator and log amp.  You can extend this to the 12-bit DAC1208 for 12-bit systems.:

http://www.ti.com.cn/cn/lit/an/snaa097/snaa097.pdf

The DAC0808 is a standard 16-pin DIP package, available cheap and everybody and his dog carries it.

[miech]

Don't use a digipot as a volume control. They crackle and pop when you change the value.