Using the EHX Cntl Knob is easy. First, connect it to your device with an expression control jack using the included 6 - foot TRS cable. Then, use the EXP 1 and EXP 2 knobs to set your two desired expression values. You can think of the counter - clockwise position as the heel and the clockwise as the toe of a traditional expression pedal. To switch between these two preset values, just step on the footswitch. The LEDs will show you which setting is currently active.
When it comes to power, you can use your pedalboard's power supply. Make sure the power source can handle the 5mA current draw of the pedal.
If you're using it with different devices, use the TRS+/- Button to match the expression polarity. This will ensure the pedal works smoothly with all your equipment.
As for maintenance, keep the pedal clean and dry. Avoid exposing it to extreme temperatures or moisture. If you're not using it for a long time, it's a good idea to disconnect it from the power source to save energy and prevent any potential damage.