Kawasaki Dual-CoolKeys – Bending Heaven.

I was recently asked about the Kawasaki Dual-CoolKeys. The reader was asking if I had any experience with it or if I knew of any cool bend points.

Coincidentally, I had been messing around with a Dual-CoolKeys, not long before. I took some pics to document the device and wanted to share them.

kawasaki dual-coolkeys

I picked two similar Kawasaki keyboards up at Value Village for about 10 bucks. The guy looked at me super funny when I bought them. But hey, that’s part of the fun of circuit bending.


Upon opening up the Kawasaki Dual Keys keyboard, I noticed an amazing thing. The Dual Keys seems like it was built by someone who loves to circuit bend. Everything is modular and the whole keyboard comes apart beautifully. The screws are easy to reach and there ins’t much that is glued down. Really, the only glue is supporting the wires.

kawasaki dual-coolkeyskawasaki dual-coolkeyskawasaki dual-coolkeyskawasaki dual-coolkeys


I did some basic bend searching and found a resistor of particular interest. The thing that makes this perticular keyboard so perfect for circuit bending is that there is not one but at least two different timing resistors. This means that the timing for the drum track and the timing for the keyboard sounds are independently controlled .

kawasaki dual-coolkeys

I will be honest, it’s been a while since I was messing around with this Dual-CoolKeys, so I can’t remember if this resistor controlled the drum track timing or the keyboard sound timing (I’m pretty sure it was the keyboard) but either way, this is AMAZING!


This is just the beginning. It’s easy to see the potential for circuit bending the Kawasaki Dual-CoolKeys into a much more amazing piece. I just wanted to get the ball rolling on the Dual-CoolKeys documentation. With some time and research, the Dual Keys, and the rest of the Kawasakies could be as popular as a Hing Hon or some of the more known synths out there.

If you have any information on the Dual-CoolKeys, feel free to shoot me an email or make a comment. If you write about, or have written about it, let me know and I’ll link to you.

Should you ever come across any of the Kawasaki line, (I have a few and they are all awesome) I highly recommend you pick it up.

DIY Drum Machine – Circuit Bending

I have been working on a diy drum machine for a while now. I wanted to post this video to show it’s functionality.

The core of this drum machine is from an electronic drum stick. You swing the stick and it makes drum sounds. The stick made 3 sounds; Snare, bass drum, and high hat.

DIY Drum Machine

When you swing the drum stick, it plays a snare sound. There are two buttons on the stick, that when pressed AND the stick is swung, play two more sounds. So this was easy to hook up to a 3-way switch with up as one button, down as another button, and middle was just like swinging the drum stick without pressing a button.

DIY Drum Machine

I rigged it up to a 555 timer and a 4017 decade counter and some pots and switches, and away it went. There is still some glitching that happens I think because of some switches which aren’t wired to ground to de-bounce them.

DIY drum machine - time signature controlerDIY drum machine - switches to control sound typeDIY drum machine - 555 timerDIY drum machine - 4017 decade counter

The 555 timer triggers the drum sound and advances the 4017. The 4017 sends a pulse through one of 10 3-way switches to hold the particular sound. The sound selection is set with the 3-way switch. I hope that makes sense.

Like I said, it’s a work in progress.

DIY drum machine - control board layout design

The case is from a kids toy (big surprise, I know). It was a light box for tracing. It use to have two lightbulbs inside and a semi-transparent screen. The cool thing about is that it has a battery compartment built in. All I had to do was modify it for the voltage I was using. I just shrunk it down. Easy (yeah right).

I painted it up white first and then spray painted a stencil of a fist on top of it. The body was also painted red. The final step for the paint job was to do some clear coat. All in all, a pretty sweet paint job.

Circuit Bending a DIY Drum Machine

In this video, you can see holes for the LEDs that will indicate which point in the sequence it’s at. I am having a heck of a time with that. It seems like, when connected, the sound plays but the LEDs don’t light up. I don’t know if it’s a lack of current or what. I have tried the LEDs in series and in parallel. Neither work now. The joke is, it all worked at one point when it was on a bread board. Upon soldering everything up, everything started changing. I suppose that is the nature of the beast.

I would love to hear your thoughts.

Happy Bending,

Arduino Sequencer


To quote noystoise…

wow, its been a long time since i have posted anything here.

It has been ages since my last post. So much has happened (Including planning a wedding and getting married). With that said, I have still been circuit bending and building things.

My Arduino Uno Micro-Controler

Recently, I purchased an Arduino Uno micro-controller. This thing is awesome. It doesn’t have much to do with true circuit bending (I know someone will have a problem with that) but it is insanely powerful.

Here is what I have been playing around with in the last few weeks.

This little Arduino Sequencer project that I have been working on is super simple to build. Really all you need is an Arduino Uno (and a computer to program it with), breadboard, speaker, potentiometer (any value) and some wires.

All of the functionality comes from the programming. The code is simple too. Basiclly, you use the built in tone generator (it’s just a square wave generator) to read the value of a potentiometer and place the value of that the potentiometer into a variable. Then you play a tone based on that value, pause, play another tone, pause, play another, etc.

The subsiquent tones are based off the original tone, they are just multiples of that first value.

The program loops and starts all over again. That’s it!

Arduino uno diy sequencer

Here is the link to the tutorial that I followed originally. It has some schematics and in depth instructions about how to set it up and how the code works.
Arduino Tone Follower Tutorial

Here is the code:

SecondHandSynth Digital Arduino Sequencer

Plays a pitch that changes based on a changing analog input

* 8-ohm speaker on digital pin 8
* Breadboard
* Some resistors and wire

This example code is in the public domain.

Original code before modification came from


void setup() {
// initialize serial communications (for debugging only):

//boot up sound
int var = 100;
while (var < 500)
tone(8, var, 50);


void loop() {
// read the sensor:
int sensorReading = analogRead(A0);
int delayTime = 175;
int durationTime = 5000;

// print the sensor reading so you know its range

// map the pitch to the range of the analog input.
// change the minimum and maximum input numbers below
// depending on the range your sensor's giving:
int thisPitch = map(sensorReading, 0, 1023, 50, 2000);

// print the mapped range

// play the pitch:
tone(8, thisPitch * 2.5, durationTime);
tone(8, (thisPitch * 2), durationTime);
tone(8, (thisPitch * 1.5), durationTime);
tone(8, (thisPitch), durationTime);

//second string
thisPitch = thisPitch * .5;

tone(8, thisPitch, durationTime);
tone(8, (thisPitch * 1.5), durationTime);
tone(8, (thisPitch * 2), durationTime);
tone(8, (thisPitch * 2.5), durationTime);

//second string
thisPitch = thisPitch * 1.5;

tone(8, thisPitch, durationTime);
tone(8, (thisPitch * 1.5), durationTime);
tone(8, (thisPitch * 2), durationTime);
tone(8, (thisPitch * 2.5), durationTime);

//second string
thisPitch = thisPitch * .5;

tone(8, thisPitch, durationTime);
tone(8, (thisPitch * 1.5), durationTime);
tone(8, (thisPitch * 2), durationTime);
tone(8, (thisPitch * 2.5), durationTime);


Try it out for yourself and let me know how it works. If you have any questions, don’t hesitate to ask.

Thanks for reading and HAPPY BENDING!

Cinco de Synth!

Happy Cinco de Mayo!

I figured I would make a special post to commemorate such a historic day… for the Mexican people.

cinco de mayo

Wikipedia says this…

Cinco de Mayo (Spanish for “fifth of May”) is a holiday held on May 5 that commemorates the Mexican army’s unlikely victory over French forces at the Battle of Puebla on May 5, 1862, under the leadership of General Ignacio Zaragoza Seguín. It is celebrated primarily in the state of Puebla and in the United States. While Cinco de Mayo sees limited significance and celebration nationwide in Mexico, the date is observed nationwide in the United States and other locations around the world as a celebration of Mexican heritage and pride.

Viva General Ignacio Zaragoza Seguín! Viva, viva!!!

I have celebrated by breaking out a bottole of – drum roll please…
Stone 10th Aniversary India Pale Ale.

05_03_2010 002

It’s from 2006! It has been sitting, chilled for 4 years! And let me tell you… it’s smooth.

05_03_2010 001

This 10% ABV led me to do something… a little crazy. I plugged my melody making sequencer toy into my drum machine. I had to play around a little but I got it to sync up almost perfectly. It works!

Here is a video.

Happy Cinco de Mayo and of course…

Happy Bending!

Inventory Management

I went on my usual route to find new synths from second hand and thrift stores.
Of course I found a couple of things.

When I got home to throw them into my closet with all the rest of them, I thought, jeez I have a lot of toys.

I figured I would make a blog post about the toys I have and what I was thinking (if anything) when I bought them.

Dollar Store Synths
05_02_2010 044
They were one dollar… can you believe that?!
Unfortunately, when I got them home I found out that they don’t have a timing resistor. I’m sure i will be able to come up with something cool to do with them but for now… they are gonna sit.

The Sound-X Kids
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I think I got this one for 3 bucks. This thing is AWESOME. It has tons of sound effects. It has some really cool drum beats (which you can even play backwards). It has a scratch pad. And, it even has a little keyboard with quite a few neat sounds. There is nothing generic about this little guy. The only problem with the keyboard sounds is that they don’t have any sustain. The are basically just little recordings that play once.

I think there is a resistor that is heating up inside too, because the case gets REALLY hot in one spot when you use the scratch pad a lot.

Kawasaki Dual-Cool-Keys
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The idea behind this one is that two people can play with it at the same time. I got it because I figured that it would have twice the polyphony (I don’t know if that is the right term) as a normal toy. Most of the toys you can only hold down 1 or 2 keys at one time, making complex chords impossible.

At the same time I got another Kawasaki (each for 4 dollars!) of the same series. It has a little 6 trigger drum pad with drum sequences already build in. It has some interesting drum loop samples as well. The keyboard to this one is only bi-phony but it has some really cool sounds to it.

Another Kawasaki
05_02_2010 043
I haven’t put batteries in this little guy yet, but I’m hopping it’s every bit as cool as it’s older brothers.

Just some Rand-O’s
05_02_2010 041
The blue/purple 4 button thing is just drum loops. They are really annoying. I have seed this little guy on youtube and on Reed Ghazala’s Website.
Reed Ghazala's  Doppler Wind
It’s called the Doppler Wind (whatever that means).

The little red keyboard, beleive it or not, is the same circuit that was in my very first post. So I guess I get to revisit that nightmare over and over again.

The DJ looking think is pretty lame. It could make a good housing but it really doesn’t do much. It has four drum loops and a few lame sound effects. I have another one of these but it is in a different package. It has drum pads on it but the drum loops are the same. That’s how I know it comes from the same place. I don’t know if those drum triggers are in this DJ one. Some day I will take them both apart and find out if they are truly the same circuit.

Playschool Guitar
05_02_2010 040
This is a pretty lame toy too. The cool part though is the built in tremolo. I don’t know whether it is just another voice that sounds like that or if it truly mods the sound of the guitar. Only time (and a screwdriver) will tell.

Let me know if you have any of these and have found any interesting bends.

Happy bending!

Insect-A-Tron – (Mini-Keys circuit bending part2)

I can’t tell you how excited I am.

I just finished my mini-keys keyboard that I was working on (Mini-Keys — A little keyboard circuit bend (part 1)).

I’m so stoked on this that I can’t even think of a good way to tell about it. So, I’m just going to show you this second hand synth and let you be the judge.

mini-keys2 015

The paint job and design

First off, I am really excited about the paint job. It’s not what I envisioned when I first thought of the design but it definitely is the best thing I have made to date.

mini-keys2 017

It was inspired by the way the synth sounds when it’s oscillators are kicked on. It’s what I think insects sound like when they communicate with one another. Lot’s of super sonic chirps and squeaks.

mini-keys2 021

Anyway, this paint job was tough to do too because I kept screwing up. I must have repainted it 3 or 4 times. Doing the stencils was increadably difficult. I found the images I wanted and printed them onto paper. Then I cut out the silhouette with an exact-o knife. Because the paint kept sparaying under the stencil and screwing up the whole thing, I finally decided that tape wasn’t enough to hold it down. I mixed some Elemer’s glue and water and coated the back of the stencil. That did the trick.

mini-keyboard 019

After the painting was finished, I made a couple of images in photoshop to label the keyboard and to put “SECOND HAND SYNTH” on the back of the keyboard. I cut them out from the plain white printer paper they were printed on and glued them to the keyboard. I tried t be cool and write 2010 on the back. I don’t know why I thought that was a good idea but I did it.

I really liked the synth identifying decal. “Insect-A-Tron”. Howerever, as soon as I had done it I realized that it should have been Insect-O-Tron. Oh well.

I finished the paint job with two coats of clear gloss. I used a polyurethane which I think had a little stain in it (it is for wood projects). It turned the white paint a little yellow. Not a lot. But enough so that it doesn’t have the cool, cold white feel to it. I’m gonna use real clear coat next time.

Synth Controls

These are the controls on the left hand side. The top switch engages the oscillators. The bottom on is a bend that I found on my own circuit. It smooths out the warble of the oscillators. The Joystick in the center of the black panel controls the frequency of the oscillators. The black knob at the top of the picture controls the bottom switch’s saturation. I don’t exactly know what it is doing but is a bit like a depth knob on a flanger pedal.

mini-keys2 020

This is the pitch knob. It is a washer glued to a little 1M potentiometer. It worked out quite nice. I just wish it was black. Maybe I will paint it someday.

mini-keys2 026

This is the push botton switch that activates the custom dual oscillator chip that I added to the keyboard. I should have made it turn on the actual keyboards chip too.

mini-keys2 024

The problems with this synth

The main problem so far is that there is no volume control. I am gonna have to get the output resistance right and solder it in there. The signal comes out quite hit and clips a lot of the sound. I had to rig a little pot in series with the keyboard just to make the video. For the life of me, I have no idea why that wasn’t part of the design.

The second problem is that there is a switch on the right hand side that activates the oscillator chips. The circuit board is powered by a 9v battery but the keyboard is powered by two AA batteries. You have to open up the entire case to get the 9v out. I guess it’s a good thing that there is a on/off switch for the 9v but I don’t like how it’s impossible to get the 9v out without taking it apart.

mini-keys2 012

The third thing that I don’t like about this second hand synth is that some of the settings don’t make any sound. I wanted the most variety of sound so I didn’t dial in the resistances of the joystick very much. Because it’s not properly calibrated, when the timing resistance it too low, you get nothing.

Oh well.

Another problem is that the keyboard is a little filled up. There is so much packed into such a small case. Next time I will definitely map out where the wires will go before I get into that phase of construction.

mini-keys2 014

The last thing that I should have done is to label the controls. I originally intended to have interesting insectoid names for all the switches and knobs. I was a little impatient and went on with out doing it. Again, oh well. Maybe I will bust out a sharpie and write it all on.

Oh! And, I forgot to put in the LED’s too. There is one for each LFO. Oh well.

I don’t even know how many hours I put into it. Many. Too many. Not enough. I don’t know. Just to get it all glued into the case it took me 3-4 hours.

Here is the first video.

Also, please click on any of the pictures and check them out on Flickr.com. There are tons more pics and you can view the larger resolutions too.

Happy Bending!!!

Mini-Keys — A little keyboard circuit bend (part 1)

I have been working on a small but complicated project for the last week or so. Basiclly it’s a continuation of the last mini-keyboard circuit that I fried. I posted some pics in an earlier post.

The original project had a dual LFO powered by a 9V battery. I was using the 556 dual timer chip to accomplish this.

Long story shore; I fried the little guy and the 556 timer while trying to adapt the keyboard for wall power.

The new keyboard and circuit design

I was lucky in the fact that I had found almost the exact same keyboard the weekend before I fried it.

joystickStuff 005

I could just substitute it in for the old one and none would be the wiser.

The only problem was that I had fried the 556 chip and didn’t have another one. I could have gone to Radio Shack or bought some online. I didn’t really want to do either. The Shack is too expensive and ordering online takes too long. I had to come up with something else.

joystickStuff 006

I decided to practice what I preach and give the lm386 a go. So I followed the schematic on the datasheet and wired a square wave. And wouldn’t you know it… It worked.

The “square wave” seemed to act a little differently than the 555 timer square wave. It seemed to have more slope on the beginning and end of the square wave shape. I know this because I had it running an LED. The LED seemed to dim as the capacitor discharged.

Anyway, I wired up two of those lm386 oscillators and played around with them. Crossed a wire here, added a capacitor there. You know how it goes.

mini-keyboard 002

Mostly, the two LFO’s are effecting the pitch (vibrato if you will). One is directly effecting the pitch and the other one is modulating the first LFO and also operating a transistor gate which is almost acting like a tremolo.

All in all I came out with a pretty good design. One that I’m sure could be patched into just about anything with a timing resistor.

The fun stuff

The best part is the joystick. It operates the both LFO’s frequencies at the same time. LFO1 is the X-axis and LFO2 is the Y-axis.

mini-keyboard 003

The really cool thing is the second LFO. As I said, it operates a transistor gate for the first LFO. These different combinations make some really interesting modulation to the sound of the keyboard. But, it also is patched into the pitch resistor array at a different place than LFO1. So, when all is said and done, the sounds that you get are really quite diverse.

I have a switch that activates the second pitch controlling LFO2 (but not the transistor gate of LFO2) which basically gives the keyboard a super alien/insect sound. When I blast that sucker, I feel like I’m hearing ants communicate.


I have only just begun to paint this beast but so far it’s turning out pretty good.

mini-keyboard 019


mini-keyboard 013

-videos and schematics coming soon in part 2