The keyboard [JenShen] used was a simple Casio keyboard with built-in voices. After tearing out the guts of the keyboard, the only thing that remained is the row of push buttons underneath the keys.
and it can also be used with AA batteries. The RockJam RJ761 is a 61-key teaching piano keyboard that comes with a stand, stool, sustain pedal and headphones. It has a touch sensitive keypad and ...