Toy Keyboard Salvage

Scrap Keyboards
So I’ve been tinkering away in my workshop on a very cool new project I think you’ll enjoy, it is still a work in progress but I should have it finished up and online next week for you guys to check out. In the meantime though I wanted to share some keyboard salvage pictures I took while tearing apart some toy keyboards I had kicking around my shop.

As someone who compulsively buys cheap used electronics from thrift stores every so often I find the random chunks of plastic lying around my shop are starting to pile up and get in my way. When this happens my destructive tendencies get a chance to come out and play. I can spend some time reducing these large monstrosities to their small and easy to store component parts.

Further I know if you’re anything like me you want to see what’s inside every toy you encounter. I’m very much of the mind that the more photos of toys and devices opened up with their innards exposed there are out in the world the easier it will be for us as circuit benders to judge toys at thrift stores or garage sales without the weird looks you get when you start taking things apart in public. Today I have three keyboards I’m going to pull apart and let you have a look at.
Simba Super Concert

The first is a “Simba Super Concert Keyboard”  which works relatively well but I have had very little luck bending. The buttons on the face seem to have been poorly constructed and many are not working very well. When I trigger these buttons directly from the board the sounds are still there so it seems this is just a mechanical issue with the keys. This is reassuring as there are a number of interesting sound samples on the board (animal sounds and different instruments) which I may incorporate into a future build.

From the board you can see there is very little going on, the small vertical board holds a black blob IC and a pitch resistor but little else. The reverse of this board simply contains a large button matrix.

Chinese Keyboard
Next up is a cheap toy keyboard from China I picked up at a discount store. There is no brand printed on it but it appears to be made by Jinjiang Shengel Toys ltd. I have to admit I did not have high hopes for this one, it sounded foul and felt worse. The plastic was extremely lightweight and poorly constructed. My favorite feature was the USB port on the right side of this photo, which is to say the rectangular hole in the body labelled USB with no port or supporting electronics to be found.

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I did have one pleasant surprise when I opened this keyboard up though. It’s probably a bit hard to make from this photo but this is a fully functioning LM386 amplifier which was used in the keyboard. I was  pleased to find an LM386 as it is a chip I am fairly familiar with and one I have worked with in the past. With some simple modifications I should be able to add gain and a volume control to this amplifier and re-use it in a future project.

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Last up for this keyboard salvage session was a Kawasaki Pro-37 keyboard. Unfortunately this keyboard was in pretty rough shape. It was given to me used and the sound circuit had been essentially destroyed from battery corrosion. I didn’t get a picture of the inside for this reason but it was not a pretty sight. That being said I was still able to salvage some useful hardware from the toy.

Spoils
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So at the end of the day I walked away from these three keyboards with several large button matrices, Some small sound generating circuits, an LM386 amplifier, a few speakers (of varying quality), several battery compartments (cut out from the keyboard bodies), several sets of keys, a small pile of switches and buttons and most importantly some space on my shelf. Hope you guys enjoyed these keyboard salvage pictures. I should be back next week with an exciting new build.

Vtech Apple – Demo

Hey guy’s I just created and uploaded a quick video to show off my progress on the Vtech Alphabet Apple. Unfortunately I was having some issues with my portable amplifier so I ran it through the internal speakers but this should still give a good idea of what the bends I’ve completed so far can do. The demo starts off a bit slow but picks up after 1:20 or so. I also get into a really interesting glitch near the end of the video using the voltage starve.

If you want to have a look back at any of the previous posts they can be found here :

VTech Apple Part 1 – Kill Switch and Line Out

Vtech Apple Part 2 – Exploration and Pitch Adjustment

Vtech Apple Part 3 – Voltage Starve

Vtech Apple Part 4 – Body Contacts

Vtech Apple Part 5 – 555 Trigger Oscillator

 

 

VTech Apple Part 5 – 555 Trigger Oscillator

circuit bending, loop trigger, 555

I have to admit for some time I have been stalled with my Vtech Alphabet Apple circuit bending project. I love the toy aesthetically and have always felt like there should be more bends available then what I was able to find. However even after hours of experimenting and dissecting this toy I was left feeling somewhat underwhelmed with the results. Over the weekend though I brought it back out determined to turn it into a more functional instrument, and to do that I needed to create a trigger oscillator.

If you want to get caught up before going forward don’t hesitate to visit my previous posts on this toy:

VTech Apple Part 1 – Kill Switch and Line Out

Vtech Apple Part 2 – Exploration and Pitch Adjustment

Vtech Apple Part 3 – Voltage Starve

Vtech Apple Part 4 – Body Contacts

Since I hadn’t had any luck finding a loop on the board I moved on to less straight forward methods. I decided what I needed was a way to send a signal at repeating intervals to one of the contacts on the button matrix to trick the Vtech Apple into thinking a button was being repeatedly pressed and trigger a repeating sound. By generating this signal independently I could manipulate its frequency and control to suit my needs.

Once I had a clear definition of what I needed to get the job done the solution seemed all to clear, what I needed was a 555 timer. By setting up an astable 555 timer as a trigger oscillator I could route the square wave signal into the button matrix to repeatedly trigger the button (or buttons) of my choosing. Further by using a potentiometer I would be able to adjust the frequency of the square wave and therefore control the time between button presses as needed.

555 astable
This is a simple mock up of the circuit I used. Note that for this to work the positive voltage must be supplied by the toy itself and the ground must be share with the toy as well. This is easily accomplished by running the power from either the positive power connection on the Apple’s circuit board or directly from the kill switch installed in Part 1 . Just ensure it is connected at or past the kill switch so that the kill switch will remove power from the oscillator as well. Similarly the ground can be connected to any ground point on the circuit.

Astable 555 circuit
After testing my plan using a breadboard I put together this small 555 timer circuit on a scrap piece of perf board I had laying around from a previous project. I did my best to keep everything as small and compact as possible as my space inside the toy is somewhat limited. I’ve seen some circuit benders using what is called the “Dead Bug Method” in these situations to further minimize the size of the circuit. When building a dead bug circuit the components and connections are soldered directly to the pins on the IC rather than onto a piece of perf board. This can be an excellent way to shrink the circuit for those really tight fits but also leaves you with a more fragile product so since I could get away with using a board in this toy I did in order to get more stability and durability from the circuit. I will revisit dead bug circuits in a future post but in the interim there are many demonstrations of the method on YouTube if you deem it necessary.

Wiring 555 Oscillator
Once I had my 555  trigger oscillator circuit built the next step was to install it in my Vtech. I started out by planning positions and drilling holes for the potentiometer, switch and LED. Once these were in place I began the process of wiring the leads I had left on the 555 trigger oscillator circuit to their respective locations on the toy. On the diagram below I have marked the approximate paths of each wire upon installation. In planning this mod I did my best to limit the number of wires crossing between the back and front sections of the toy as these wires tend to get put under a lot of stress when the toy is being opened and closed. To achieve this I pulled power from my kill switch and sent ground directly to the negative terminal on the battery box. Since the switch and pot are mounted on the back portion this means only the pulse out wires have to cross over to the front half of the apple.

Wiring Vtech Apple

You may also notice that there are two pulse out wires leading from the switch to the button matrix. I used a 3 position on-off-on switch for this bend which allowed me to send the pulse to two locations based on the switch position (as well as nowhere in the off position) By connecting the opposing sides of the switch to different positions on the key matrix I am able to choose between two different buttons when running the oscillator. If you were so inclined and had the space to work with you could take this even further using a rotary switch or patch bay to allow you to select where the pulse was being sent. If there is a specific key you are after which you are not finding by touching the pulse to the solder points on the matrix try using your probe to connect sets of two points on the matrix together. If you find that this is necessary to get the input you desire this can be done by bridging the two points with a transistor and feeding the pulse into the base (more on that in a future article).

Finished Vtech Apple Loop
Once everything was wired I secured the 555 circuit and LED with hot glue, taped down all the loose wires and closed up the toy. I have to say after playing with it a bit I am really enjoying this modification. I’ve been able to produce a host of strange noises and effects and without having to use a hand to continually press the buttons I feel like I’m finally able to take full advantage of the other bends on this device. I’ve been having particular fun using the power starve to produce glitches in conjunction with the continuous oscillating noise produced by raising the rate of the 555 to high frequencies.

That’s all for today but I hope you guys have fun. Happy soldering!