A drone synthesizer for your pedalboard, the Drone Tone is a pitch and rate controllable square wave oscillator in a guitar pedal format.
It can be used stand-alone or with an instrument input, however, the instrument input is unaffected and is simply buffered and passed-through to the output jack. The mix control sets the volume of the square wave oscillator at the output jack.
MKIII adds onboard tap tempo, tempo sync input (0-5V), internal pitch range control, and top mounted jacks.