altimeter adjustment

I'm using a new Leo Bodnar controller and wish to zero my altimeter subscale before flight. At the moment I accomplish this by pressing a keyboard key to increase and another key to decrease. I'd like to make it more realistic by adding a knob on the altimeter (subscale adjuster). Can anybody tell me what type of knob to use and where i can buy one? I'm running condor flight sim in a glider cockpit with a tft screen behind the instrument panel

Hi

You need use a ENCODER , i dont know if Leo Bodnar controller support this type of switch.
I use opencockpits solution , the master card accept this type but only support ENCODER GRAY.

See here -> http://www.opencockpits.com/catalog/encoder-p-100.html
http://www.opencockpits.com/catalog/images/encod.jpg

Sorry for my english.
Good Luck!