I went thrift shopping the other day and I found a pretty cool toy that looked like it would be great for circuit bending. It didn’t have batteries when I found it so I didn’t test it out at the thrift store. I should really bring batteries with me or have the attendants test them at the store but hey… I can always use another toy for my circuit bending collection.
The thing that caught my eye about this Hanna Montana electric guitar is that it had an echo knob. This could only mean that there was some kind of ic chip that handles the delay. I had to have it.
I went strait home, powered her up and started pushing her buttons. She sucks. The main problem is that all the buttons on the “fret board” are sound effects. Now, this would be awesome if you could just use the sound effects in a circuit. But you can’t. When no sound is being played and you push one of the sound effects buttons, the first press triggers one of 3 Hanna Montana songs to start playing. This is bad. Really bad.
I don’t know what the name of the three songs that are programmed into the circuit but I now know the words. I figured it was odd that the sound effects triggered the songs. So, I youtubed the guitar and found a video where it seemed (to me anyway) that the sound effects could be played independently. This sparked me to spend the next two days trying to find a crossed wire or short circuit somewhere that could be fixed.
I found nothing.
I still think that there is a bad connection somewhere but I can’t for the life of me figure out where it is. So the circuit will forever play one of Hanna’s crap songs.
There is a silver lining to the purchase of this piece though. The circuit has an independent circuit that controls the volume (via an lm386 of course) and a chip that does in fact create the echo effect.
That chip is my dear old friend, the pt2399.
It has some different identifying letters but it’s the same one. You can see that the circuit design is much like one of the schematics in the 2399’s datasheet. It’d has only a potentiometer controlling the amount of echo but that could be changed with little effort.
The point that I wanted to make was that you could easily get one of these Hannnas and strip out the echo circuit and use it on any project you like. The circuit must be very similar to the one found in the Barbie Karaoke machine. You might be able to use the schematics and diagrams found at http://casperelectronics.com/finished-pieces/barbie-karaoke/.
If you are interested in playing around with the circuit, I mapped out some of the main controls for the primary voice chip inside the guitar. That and the lm386 amplifier circuit. As seen below.
click on the image to enlarge.