How do I set 256 steps into a rheostat vs potentiometer?

All of the circuits I see in the domain, take a voltage sampling from 2 outside wires of the potentiometer, then divide by 1024, then 256 using one side and the tap.

How do I get the sample voltage from one side and tap (rheostat) and accomplish that same thing.

I use a microphone that has said rheostat built into it to reduce my mp3 music on my laptop using the “B” key to decrease volume, and “N” to increase volume.

I am trying to use the full range of the rheostat (@ 25-30K) to vari the volume. 256 steps would be more than adequate. (each step = one click of the keyboard, B or N) I am using the Arduino UNO to program the keyboard controller board from a keyboard, USB into my laptop.

I am using an existing microphone setup from

Thanks for any help out there!
Davekatt :grin:

You won't get a full range (0-1023) but if you make a voltage divider with a fixed resistor and your variable resistor you can get a wide range of readings. Connect the fixed resistor between +5V and the analog input pin. Connect your variable resistor between the analog input pin and Ground. If your VR goes to 30k and your fixed resistor is half that (15k) you will get values in the bottom 2/3 of the range (roughly 0 to 680).