unless i am mistaken, the major difference between the monotron and the gakken is the gakken has a stylus and plate, the monotron has the ribbon/ the gakken sh0uld be even easier than a stylophone to add a real keyboard to, the monotron, not so sure...the gakken (like a stylophone), i assume the stylus is common, and the plate is positive, right? if that is all there is to it, a keyboard would be easy to apply. but how do i do this to the ribbon? i tried a resistor ladder on an oscillator i built and i could not get the notes in the right pitch...