Little Composer – The Melody Making Sequencer

I can’t really finish my drum machine right now because I am waiting for some 3-way switches to arrive from ebay. I need to learn to stock up. I am way to impatient for this whole “12-21 days shipping from Thailand” thing.

What to do instead?
I picked up this second hand synth the other day. It’s called the Little Composer by Leap Frog.

05_03_2010 001

It’s really more of a musical learning toy for children. It has an 8 note measure that you can adjust each not from low to high C (only in the key of C, of course). The Little Composer has 7 voices. There are three instruments; piano, guitar and violin. There is also a woman voice that tells you what the note is. A, B, C, D, E, F, G… That is really annoying. And finally there is a dog, a cat, and a frog. These only sound good when they are clocked really high or really low.

05_03_2010 004

There are also a bunch of songs too but they are all lame. I suppose that they could be kind of cool clocked real low because the would go for a really long time but I don’t think I will include them in the final build.

05_03_2010 005

The ocatave has no sharps or flats. which is unfortunate. It would be awesome to have a full octave. Of course, if one were to add a pitch bend, one could hit any western key that they wanted.

05_03_2010 007

Naturally, that’s just what I did. I removed the timing resistor and added a pitch bend in series with about 5k ohms (i think),

Here comes the cool part. When you press the play button, this melody-maker only goes through the measure once. This is a real bummer. How is a child suppose to learn music if they can only play one measure at a time. So, I added an LFO from a 555 timer.

05_03_2010 003

It took me a little while to figure out how to make it work. I ended up just running a 10k out of the output from the 555 timer and going strait to the pin on the control circuit that handled the play button. That worked great. I thought I was going to have to do some weird thing with a transistor that I wouldn’t fully understand for the next couple of years. Luckily, that wasn’t the case.

So, if you tune the LFO frequency, as I am doing in the video below, you can get the melody maker to act as a sort of 8 note sequencer. SWEET RIGHT?!

Next, I think I am going to have to add the usual LFO to modulate the pitch and maybe even a tremolo. I’m also waiting on some frequency divider chips from ebay. Maybe one of those will make it in too.

05_03_2010 002

Happy Bending!


Drum Machine – Work in Progress

This is the project I am working on right now.

This is a drum machine that I am making. The core is from an old electronic drumstick that I found at a thrift store. It is opperated by swinging it just like a real drum stick and stopping it in mid air. When the electronic drumstick stops, it makes a sound.

The default sound is a snare but there are also two more sounds. If you hold one button and swing the electronic drum stick it makes a bass drum sound. The other button has a crash symbol.

The drum machine is being timed by a 555 timer and a 4017 decade counter. It will have a 3-way switch for every step in from the 4017. One for each sound. In addition, it will have an on/off switch and (if all goes well) a pitch adjustment for every step.

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
05_02_2010 038
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
05_02_2010 042
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 — Circuit bent toy keyboard — schematic

Here is the schematic of the circuit that I added to the Insect-a-tron second hand synth.

joystickStuff 004
You can see a bigger picture if you check out the flickr page here.

NOTE: The 50k pot is a dual (stereo?) and I added two leads coming off the second half. One goes to +v and the other goes to somewhere around the 10k resistor all the way on the left hand side of the left lm386 LFO. There is a switch that will deactivate this second connection. That is what the lower switch on the left of the keyboard controls.

I guess you could say I kinda did a bend on my own circuit.

Here is another… better… video I made of the Insect-A-Tron.

I didn’t realize it but at around 1 minute it almost sounds like the X-Files theme song!!!

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 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

Potentiometers from an X-Box controller joystick! – a how to guide

In this entry I will show you how to take apart an x-box controller and then how to extract the joystick. I will also show you how to remove the spring from the joystick so that you don’t have the “return to center” action that the controllers come with.

But first…

The story

I was at my favorite place, a thrift store. While making my rounds, looking for second hand synths, I came across an old X-Box controller. I have seen other people use joy sticks in their circuit bending projects but I have never seen them for sale (mostly because I never though to look).
x-box controller - potentiometer

I know that the controllers have a lot of control and accuracy. So, I figured that there must be two potentiometers for each joystick. Otherwise, you couldn’t camp out in a tower, aim your gun at your opponent’s head and snipe him in the head. You would be able to do it if there were four buttons behind the joystick.

Naturally, I bought it.
Naturally, I took it apart.

inside an x-box controller - see the two potentiometers?

(note: in the above two pictures the controllers are different… this is because I didn’t take them. I stole them from somebody on the web. Sorry. I won’t do it again… in this post… )

There isn’t really much worth taking, besides the joystick potentiometers. The rest is just simple contact push buttons. Too bad really. For what they cost, I thought there would be much more inside.

The Joystick

The X-Box joysticks are just two potentiometers. Obviously, one is for the x-axis and one is for the y-axis.

joystickStuff 008

The pots measure at about 10k when they are fully pressed in one direction. They rest at about 5k with a small amount of resistance opposite the 10k side.

The best way to get the joystick out is to use some wire cutters and just cut the PCB around the joystick. Make sure not to get to close to the joystick housing because you can crack the PCB too close to the pots. When this happens it separates the potentiometer from the joystick housing and breaks it a little. You can glue it back on but it’s annoying.

These things are great! I put one in the second hand synth project I am currently working on. My synth project has dual LFO’s producing two square waves. One square waves modulate the pitch and the other modulates the volume. It’s kinda like vibrato and tremelo together. There is also some cross modulation of the two square waves. The joystick is the perfect control for the rate/frequency of each individual oscillator. Thus, creating some really awesome sounds.

x-box joystick taken out

The one problem with the joysticks is that they always return to center. This is cool but then you always have to keep one hand on the stick if you want to keep the potentiometer settings that you have going.

As I said, my current second hand synth project has two LFO’s. The combination of the two produces some really interesting modulation of the original synth sound. With the joystick, I had to have it be able to stick to the setting I had set it too and not immediately return to center every time I wanted to adjust something else.

What was a boy to do? …

How take the springs out of the joystick

So, I took each individual joystick apart too!

This was no easy task. The main problem is that you have to get the PCB away from the joystick housing. You have to melt the solder points and pry it with a screwdriver at the same time.

The housing itself has four contacts which are soldered to the PCB and then there are tree pegs on each of the potentiometers. To make matters even worse, there is the push button switch (you push in on the joystick and it clicks the push button) that has four solder points.

In the end I did have to clip away at the PCB. BUT BE CAREFUL! As stated earlier, you can mess up the joystick and seperate the pots from the rest of the joystick. I did this on one of them and it was no fun task to get it super glued (and hot glued) back on.

joystickStuff 009

Once the PCB is off you can pull the little metal tabs (part of the housing) that are holding to plastic bottom on. Once the four tabs are pulled away from the base you can pop the base off and pull the guts out.

the joystick of an x-box controller all taken apart - it's in pieces!

joystickStuff 010

Take the spring out and re-asemble the hole unit. You can even add a bit of perforated circuit board to the bottom to strengthen the whole unit.

Kinda cool really. The device itself is ingenious… if you ask me.

And there you have it. You can keep the button or not. I couldn’t think of what to do with it on the project I have going right now (TONS of Ideas came to mind but nothing would work with the space availible). But, you can bet that I will include it in the future.

Happy Bending!!!