Circuit Bending Those Adorable Voices

Leapfrog make some pretty awesome kids electronics. Especially admirable is the low cost, the battery life, and the audio quality of these devices. This circuit bending hack takes advantage of those audio circuits by turning the Alphabet Pal into your lead vocalist. The performance in the demo video begins with some impressive tricks, but just wait for it because by the end the little purple caterpillar proves itself an instrument worthy of a position beside that fancy Eurorack you’ve been assembling.

The image above provides a great look inside the beastie. [Jason Hotchkiss] mentions he’s impressed by the build quality, and we have to agree. Plus, look at all of those inputs — this is begging to leave toyland and join the band. With an intuitive sense that can only be gained through lots of circuit-bending experience, he guessed that the single through-hole resistor on the PCB was used to dial in the clock speed. That made it easy to throw in a trimpot for pitch-bending and he moved on to figure out individual note control.

All of those caterpillar feet are arranged in a keyboard matrix to detect button presses. After pulling out the oscilloscope for a bit of reverse engineering, [Jason] grabbed a PIC microcontroller and added it to the same solder points as the stock ribbon connector. The result is that the buttons on the feet still work, but now the Alphabet Pal also has MIDI control.

Take a look at the writeup for full details, and the video after the break to hear it in action. If you’re a fan of circuit-bent toys, this pretty pink keyboard hack always impressed us, especially the spring reverb that was added!

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Circuit Bending A TV For Better Input

If you haven’t noticed, CRTs are getting hard to find. You can’t get them in Goodwill, because thrift stores don’t take giant tube TVs anymore. You can’t find them on the curb set out for the trash man, because they won’t pick them up. It’s hard to find them on eBay, because no one wants to ship them. That’s a shame, because the best way to enjoy old retrocomputers and game systems is with a CRT with RGB input. If you don’t already have one, the best you can hope for is an old CRT with a composite input.

But there’s a way. [The 8-Bit Guy] just opened up late 90s CRT TV and modded it to accept RGB input. That’s a monitor for your Apple, your Commodore, and a much better display for your Sega Genesis.

There are a few things to know before cracking open an old CRT and messing with the circuits. Every (color) CRT has three electron guns, one each for red, green, and blue. These require high voltage, and in CRTs with RGB inputs you’re looking at a circuit path that takes those inputs, amplifies them, and sends them to the gun. If the TV only has a composite input, there’s a bit of circuitry that takes that composite signal apart and sends it to the guns. In [8-bit guy]’s TV — and just about every CRT TV you would find from the mid to late 90s — there’s a ‘Jungle IC’ that handles this conversion, and most of the time there’s RGB inputs meant for the on-screen display. By simply tapping into those inputs, you can add RGB inputs with fancy-schmancy RCA jacks on the back.

While the actual process of adding RGB inputs to a late 90’s CRT will be slightly different for each individual make and model, the process is pretty much the same. It’s really just a little bit of soldering and then sitting back and playing with old computers that are finally displaying the right colors on a proper screen.

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Good Old-Fashioned Circuit Bending With Patient Alpha

For a lot of us some sort of audio circuit was our first endeavor into electronics. Speak and Spell, atari punk console, LM386 in a mint tin, sound familiar? If not, you should do yourself a favor and knock out a couple of those simple projects. For those of us who have done a bit of what the kids are calling circuit bending, [Nickolas Peter] brings us a familiar hack with his Patient Alpha project. You can see a time-lapse video of the build process and a short demo in the video after the break.

[Nickolas] did a few mods to his 2013 Executor key fob; the obligatory potentiometer for resistor swap is always a crowd pleaser. Adding an audio out via 3.5 mm jack is something that some of us wouldn’t have thought to include, but it lets the Executor scream into your serious audio gear for maximum eargasms. It’s worth mentioning that [Nickolas] does a good job with this hack’s finished look, albeit he started with a product in an enclosure he still goes to the trouble of custom fitting all his bits in an aesthetically pleasing way. And then he made a second.

We have covered circuit bent projects aplenty: from an old school take on circuit bending to one with a ratking of wires built on a proper bit of audio kit. Dig out your soldering iron and dig in.

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Digitally Controlled Circuit Bending

Circuit bending doesn’t get a lot of respect around some parts of the Internet we frequent, but there is certainly an artistry to it. Case in point is the most incredible circuit bending we’ve ever seen. Yes, it’s soldering wires to seemingly random points on a PCB, but these bend points are digitally controlled, allowing a drum machine to transform between bent crunchiness and a classic 1980s drum machine with just a few presses of a touch screen controller.

All circuit bending must begin with an interesting piece of equipment and for this project, [Charles], the creator of this masterpiece of circuit bending, is using a Roland TR-626, a slightly more modern version of the TR-606, the percussive counterpart of the infamous TB-303. The circuit is bent in the classical fashion – tying signals on the PCB to ground, VCC, or other signals on the board. [Charles] then out does everyone else by connecting these wires to 384 analog switches controlled by an Arduino Mega. Also on the Arduino is a touch screen, and with a slick UI, this old drum machine can be bent digitally, no vast array of toggle switches required.

[Charles] has put up a few videos going over the construction, capabilities, and sound of this touch screen, circuit bent drum machine. It’s an amazing piece of work, and something that raises the bar for every circuit bending mod from this point on.

Thanks [oxygen_addiction] and [Kroaton] for sending this one in.

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Intro To Circuit Bending

Electronic musical instruments are a lot of fun for a hacker because, with a small palette of tools, know-how and curiosity, they are easily modified. As with any hack, there is always the chance that the subject will be ruined, so it’s not necessarily worth the risk to muck about inside your thousand-dollar pro synthesizer. Luckily for all of us, there are shovel-fulls of old electronic musical toys littering the curbs and second-hand shops of the world. These fun little devices provide ample opportunity to get familiar with audio electronics and circuit bending techniques.

A note on definitions: the term “circuit bending” can be synonymous with “hardware hacking” in the world of audio electronics, and we have seen some debate as to which term is better suited to a given project. We welcome you to share your viewpoints in the comments.

Keep reading to get started.
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Notacon 2008: Circuit Bending Will Get You Laid


[Pete Edwards] and [Fred Owsley] openly admitted that the title was the most thinly veiled audience-bait ever constructed. Nevertheless, they poured through a great talk covering the basics of circuit bending and some of the pieces they had built over the years. Fred said that what attracts him to circuit bending is the hands on approach to something very scientific i.e. he can figure out how to construct an interesting circuit by rubbing his finger along the back of the board. As far as where to start: always a battery powered device and use the toy store as a last resort. You’re going to tear the thing apart so why pay for it? Dumpster diving, garage sales, swap meets, and flea markets are all places to look. Parts don’t need to be anything better than grab bag either. They suggested an easy first step is dropping the operating voltage of your device and seeing how it reacts. Pete and Fred had several examples of devices they’ve modified: Speak & Spells, Casio SA keyboards, Barbi karaoke machines, and the voice changing gas mask pictured above.

The Bent Festival for circuit bending is coming up soon if you’d like to see more. You can also check out these links for more information on circuit bending.

Notacon 2008: Circuit Bending Intro


The first talk we went to at Notacon was [Sam Harmon]’s great introduction to circuit bending, the process of modifying sound generating electronics to create new musical instruments. Reed Ghazala is considered the father of circuit bending for his pioneering work starting in 1966. Sam pointed out that a “prepared piano” could be considered the non-electric precursor to circuit bending. It involves the musician placing different types of material on the piano’s components. Sam presented many different examples of where to start with circuit bending: the Casio PT-10, PAiA Theremax, Atari Punk Console. He also mentioned a couple AVR projects: AVRSYN and todbot’s Arduino work.

The session ended with [Thom Robertson] showing off the Weird Sound Generator he built and his GHX software for playing real music with a Guitar Hero controller.