Circuit Bent Casiotone CT-460

So my latest circuit bending foray is a ca.1987 Casiotone CT-460 keyboard that I picked up at the local Goodwill for 15 dollars. A quick Google search led me to a pdf of the user's manual, and a couple of circuit bending sites and youtube videos. After verifying that the thing still worked (via slightly balky 9v adapter plug; I rewired the battery connection to accommodate a 9v battery & added a kill switch) I pulled the back panel to take a look at the circuit boards. I poked around a bit & found tons of bend points associated with the chip just to the right of the main cpu (blue box in picture below).

I found that most folks who bend Casiotones put together a box of banana jacks (one jack for each bend point) that can be connected by a lead wire with two banana plugs that are also connected to a potentiometer. Next step, though, is to identify all of the bend points and solder wire leads to each - I found 42 points, plus an upper-pitch point (the two red wires in the second photo below).


Wires are then threaded to box attached to side of Casiotone and soldered to the banana jacks. Solder solder solder:


Finished box with everything soldered in place, and two sets of lead wires. Bend points are linked to the grid of 42 plugs at the top, and the two connecting plugs to the 100k pot are at the bottom.


Here's a clip of the finished keyboard demonstrating the rhythm function using the "16 Beat 1" setting - I also made a temporary 100k pot connector out of an old tuna fish can so I could play around with a second set of lead wires:



Next up is a Yamaha PSS-270 keyboard. Stay tuned...

Cigar Box Megaphone Amp

So my latest diy project was to build another megaphone guitar amp, this time using a 10 watt megaphone that I picked up at Harbor Freight (they were on sale for $5.99 so I picked up two, one of which I trashed in a fit of impromptu circuit-bending... but that's another story). I decided to use an old square cigar box for the housing. Here's some pics of work in progress:

out of the box

Disassembled megaphone with cigar box.
Rather than using four "C" batteries for juice I attached a 9v power supply.


tricked out box interior with center panel for holding the speaker


Front of box with pilot hole drilled for cutting circular opening for speaker.
I had to first replace the front panel (which was cracked) with a piece salvaged from another old cigar box.


Inside of box with attached speaker (which I spray painted black), battery, and 1/4" input jack. The back of the speaker is bolted to the center panel, with a piece of wire screening (also spray painted black) glued to the inside front panel. My original plan was to somehow mount the circuit boards with the on/off button and volume control so that they poked out either the top of the box, or the back - easier said than done...


finished box - front



finished box - back
I stuffed the circuit boards back into their original housing & cut a hole in the back of the box, then slathered with airplane glue to hold in place - not pretty, but it works (nice buzz from the glue, though).


input line on the right, output line on the left.
running a line out to another amp/speaker creates tons of fuzz and distortion



interior of finished box - battery is held in place with velcro so it doesn't rattle around.
side panel is secured in place with two screws.

DYI Guitars - II & III

Following my first wine box guitar build I've decided to build some more. For the body of the second guitar I used a stainless steel strongbox that I picked up at our local Goodwill for 99 cents. I sanded off the battleship gray paint for a brushed steel surface and drilled sound holes using our shower drain as a template. Pretty straightforward build - had to use a dremel w/ diamond cutting wheel to cut through the stainless steel box to mount the neck. The most time-consuming steps were sanding the paint off the box and mounting the frets.

Some pix of the finished piece:

view of the bottom of the guitar showing 1/4"output jack

interior view showing piezo mounted to the underside of the neck, and output jack

For the body of the next guitar I decided to use a tin children's tool chest that I picked up on ebay. Again, pretty straightforward build. I was able to do most of the modifications to the body using tin snips, and once again used our shower drain as a template for the sound holes. When I wired this one up I added a pot for volume control, and used an old brass button as the volume knob.

Some pix:

detail showing brass volume knob. "This one goes to 11."

the neck is secured to the tin box body with rivets.

volume control and output jack.

Almost forgot - I also rewired and added a volume control to the wine box guitar. I fashioned a knob out of an old gear and plastic halloween skull: