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I have a 1 turn 10k Ohm Potentiometer attached to the analog input of an Arduino. Now, the full range of the pot gives me values from 0 - 1023, nothing new.

The problem: I only want to measure change within a small rotation range of the pot. So the start position is at 30° rotation and the end position is at 40° rotation. I want to achieve a maximal numerical range within those 10°.

Are there any potentiometers that don't turn about 270°? Or can I maybe achieve it by putting more resistance in line?

Appreciate the help! Thank you, Marcel

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  • \$\begingroup\$ You can use an external dac with higher resolution. There are plenty of breakouts in ebay, amazon, etc. \$\endgroup\$ – Wesley Lee Feb 13 '18 at 9:15
  • \$\begingroup\$ Hey Wesley, thank you! Does this mean it gets more values within its rotation range that I can work with? \$\endgroup\$ – fox Feb 13 '18 at 9:21
  • \$\begingroup\$ It means that you can set the high and low limits of the ADC reference externally. You should use a single turn pot too. You're looking for 10° out of 3600° or about 1/3% of span on a 10-turn. With a single turn you'll be looking at 10° out of about 300° or 3.3% of span. \$\endgroup\$ – Transistor Feb 13 '18 at 9:37
  • \$\begingroup\$ You could add a DC amplifier with suitable gain and offset - a "rail to rail" opamp and about three resistors. If the full pot range is 0 to 5V, 30 to 40 degrees may be 1 to 1.5V, so you would need a 1V offset and a gain of 10 to get 0 no 5V on the output. \$\endgroup\$ – Brian Drummond Feb 13 '18 at 11:34
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    \$\begingroup\$ I'm not sure you have really described what you want to do here. Are you saying your mechanical system will only rotate the pot 10degrees, or are you saying with a 10K pot the user will only usually have to adjust it within that narrow range. Some more application information would be nice... \$\endgroup\$ – Trevor_G Feb 13 '18 at 13:49
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Try this circuit, using 2 pots; its standard method to set coarse, and then fine voltage into ADCs, to examine how the output code bits vary to ensure there are no missing codes

schematic

simulate this circuit – Schematic created using CircuitLab

you may need to insert R8, and use the top node of R8 as your output RTN node, thus allowing testing somewhat below 0volts Vout.

Make the capacitor as large as possible, electrolytic if you wish. Watch out for microphonics (vibration sensitivity) of ceramic caps.

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