Thursday, August 21, 2008



last Thursday i started this project. the idea came to me as soon as i found this toy guitar at the bins. i wanted to have a guitar with a keyboard on the fretboard. everything else kind of came together on its own.

after opening it up, i noticed that the circuit was capable of having sharps and flats. it was just a matter of wiring them in. my first idea was to have an A.R. generator triggered by the keys that modulates a vcf. it took a long time to make this all work. the one major problem was that there was no capacitor to switch in order stretch the note long enough to catch the end of the a.r. generator. all i could find was a short that held the note until the auto reset kicked in. and since the vcf sounds best when the keyboard is under clocked, the note would hold for like 2 minutes. after a bout two days of bread boarding, i decided that this circuit was a lost cause. it sounded really cheap anyway and it had a bad case of monophony. after searching my toy collection for a new direction, i found this:
despite its size, this keyboard is actually extremely compact.
this is the amplifier
the keyboard is 4 voice polyphonic, 10 rhythms, 10 timbres, auto accompaniment with 5 timbres on each bass and chord, record and playback, drum record and playback, 6 drum sounds, stereo amplifier, on and on and on.... and it sounds really really good for a cheap toy keyboard. its clocked at 3.58MHz. needless to say, there are too many function switches to fit on the guitar that i have, so i got an idea for a switch program pad:
coincidentally i found this at the bins the same day i found the guitar
i got 45 switches down to 15. the only problem is that you will have to have a sort of truth table in front of you to make it work. 5 of the switches will have led indicators for different functions. if i have enough juice left after everything else, i think i'll try to put stereo level meters behind the other 10.
ok, so now that i have a sort of plan and i have completely deconstruct and documented the keyboard, i can finally move on to my favorite part cutting up the plastic and fitting it all together.

template for hole
guide lines
littler keys
fits good
mazel tov
dirty hole
clean hole
switch pad holder
switch pad
with buttons
done for today
i dont think this will all fit on one page so i'm going to cut myself off here.


  1. Thank you very much for your tips, sure i will follow your tips. Great really helpful information posted by you.