Lately I’ve been playing around with circuit bending and wanted to share some of my progress with you as I have found it to be an interesting and rewarding way to create new and unique instruments. I will be posting more complex bends and projects in future but before we get too deep into circuit bending I wanted to quickly go over two simple modifications which I do to essentially every toy I bend. Today I’m going to add a simple kill switch and a switched output to my VTech Alphabet Apple toy. These modifications are a great way to start getting familiar with the circuitry of a new toy and can prove invaluable as you continue exploring and bending the circuit and developing it into a unique and bizarre noise machine.
Our Victim
Though these modifications should work on nearly any toy you decide to modify the victim I will be demonstrating them on is a VTECH Alphabet Apple which I purchased from a local thrift store for 4$. When choosing a toy to bend I like to visit the local thrift stores (Value Village, Salvation Army, Goodwill) for two reasons, first you can get great toys for outrageously cheap and second it’s the easiest way to find toys from the 80s, 90s and early 2000s which are by far the best for bending. There have been several iterations of the Alphabet Apple produced by Vtech with a similar aesthetics but very different internal workings, this particular model seems to be the most popular and was released early in the year 2000.
The first step once you get the screws out and open up the toy is to take pictures, lots and lots of pictures, using a digital camera or phone. These photos will allow you to mark down any bends or notes you find down the road and can also be used as a reference if anything goes wrong. Often times the cheap solder joints attaching the wires in these toys can come disconnected and the photos can help you reattach them where they belong. Here i s a picture of the circuit from my Apple :
The Kill Switch
When we circuit bend a toy we are forcing it to operate well outside of the factory parameters and this can cause …problems. We are forcing the processor to run at unusual speeds and sending data in and out of the chip sets in ways that were never planned for. Often this will cause the system to crash or lock up which can often only be rectified by removing the batteries and allowing the circuit to reset itself. This can be time consuming and frustrating, especially if the battery compartment is difficult to reach or needs to be unscrewed to access.
To simplify this we will add a basic switch along the red positive power line to allow us the disconnect the batteries at the flick of a switch. Simply cut and solder the switch onto the power line, drill a hole in the casing and mount it as seen below :
Adding An Output
Next up we will be adding an audio out jack, this will allow you to send the audio signals from your toy to a mixer, an amplifier, headphones or even effects and filters. One thing which consistently amazes me is the quality of sound you can often get from these toys once you bypass the cheap built in speaker and run them through a proper playback device, not to mention how much deeper or more interesting you can make the output by running it through a couple simple filters, or perhaps a guitar pedal or two, the possibilities really are endless.
Before we get started lets have a look at a quick schematic to get an idea of what we will be doing :
As you can see above this is a fairly simple procedure, essentially we will be cutting the positive wire going from the main circuit board to the speaker and adding a SPDT (on-on) switch. This switch will allow us to either send the signal from the board to the speaker normally allowing the toy to be played via the built in speaker or to divert the signal to an output jack we have added which will effectively turn off the built in speaker and send the signal through to whatever we plug the toy into. From here the sleeve tab on the jack is connected back to the point where the speaker wire returns to the board thus completing the circuit.
The resistor placed across the jack is there as a safety measure, most speakers have a certain level of impedance which the circuit was designed to have while running (You may have heard speakers referred to as 8 ohm or 4 ohm speakers this refers to the impedance or “resistance” they place in the circuit) Since we’ve bypassed the speaker we have removed this impedance from the circuit and need to replace it with the resistor.
Before we wire this it is important to inspect the toy and decide where the switch and jack will be placed, I generally like to drill my holes and insert the components before doing the majority of my soldering but this is really a matter of personal taste and depends how tight a space you are working with. Be especially careful when placing the 1/4 inch jack, make sure to leave enough room behind it not just for the connectors on the plug but for the male 1/4 inch jack which will be inserted into it.
Once you’ve planned the location for the components you can wire them to the circuit. Take care to leave enough wire to reach from the board to the components without leaving an unnecessary amount of slack. The green and orange wires which are taped to the back of the keypad lead from the board (at the speaker output) down to the center pin of the switch and then from one of the outer pins of the switch back up to the positive side of the speaker. From the opposite outer pin of the switch you can see the small purple wire leading to the jack tab, the 10 ohm resistor across the jack and the second green wire leading from the ground (or sleeve) on the jack back to the audio return on the circuit board. Give it a test and you should be in business.
Now that we have these two simple modifications in place we are able to quickly cut power and reset the toy if we run into a crash or lock up, and we can pipe the audio from the toy directly into any other device which will accept an audio input. With only a handful of solder connections and four or five components we have transformed this simple toy into something much more versatile and have prepared it for the treachery we will soon be visiting upon it. Now the real fun can begin, Next time we will be looking at adding a pitch bend knob to the device and will begin searching for some glitches we can exploit to turn this “Learning Device” into an outlandish electronic instrument.
Click Here To Continue With Part 2