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.

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Scrolling marquee made from GE Christmas lights

[John Riney] picked up three strands of addressable Christmas lights and used them to make a scrolling marquee. You may remember that the G-35 lights were hacked at the beginning of December, and we saw a project or two that involved these fun toys.

In order to make the display [John] modified the original packing material to hold three strands in a six by eighteen grid for a total of 108 pixels. In the video after the break he points out one interesting feature of the strand that we don’t remember from looking at the original hack; each bulb’s address is not fixed, it can be set after power-up. This works the same way as sending color data, except that you just send the address. This makes controlling a grid like this extremely easy from a microcontroller programming standpoint. Once all of the addresses have dropped down the serial bus, you’re ready to start sending color and intensity data packets.

The setup is fast, bright, and beautiful, taking just three pins of an Arduino for control. The only thing holding us back from trying this ourselves is the $150 price tag. But that was before the holiday, and we have heard some whispers about closeout deals on this product.

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Digitizing player piano rolls

What do you do with 100 player piano rolls but no player piano? You come up with a way to digitize the information for MIDI playback. The rolls have 90 columns worth of holes, 88 for the keys and two more for pedals. Voids in the paper cause a note or pedal to be played, so an optical sensor can be used to transform the analog data into digital information. Simple enough, you’ll just need 90 sensors. But this brings up quite an alignment issue. The solution is to use fiber optic cable to position the IR light source in a hand-made 0.2″ spaced jig. At least the spacing meshes nicely with standard 0.1″ protoboard, which is what was used for mounting the sensors.

[Thanks Mike]

Button cell connectors for breadboarding

We’re working on a project that has a battery backup, but we don’t have any more coin cell holders on hand. No problem, we remember seeing a double pin header used for this. But when we tried to shove the CR2032 battery in between the pins it was a no-go. We could swear we’d featured a project that does this but couldn’t find it here at Hackaday. After much searching we came up with the Guerrilla battery holder which is seen on the left. No wonder it wasn’t working, the CR1212 in that picture is a much smaller package. So we figured we’d have to come up with something else, until inspiration struck.

There must be some other way to configure the pin header to work with a fatter cell body. On the right you can see that a diagonal orientation works like a charm. Join us after the break for a couple of close-ups of that connector and our thoughts on using this with a variety of different cells.

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Speed up Web Browsing in Linux

In modern computer systems, the biggest bottleneck of information tends to be in communicating with the hard disks. High seek times and relatively slow transmission rates when compared to RAM speeds can add up quickly. This was a necessary evil back when RAM space and costs were at a premium, but now it is not uncommon to see 4GB of RAM on laptops, and even 12GB on desktops. For  users whose primary computer use is browsing the internet (either for work, writing articles, or lolcats) and have some extra RAM, moving the browser cache to the RAM from the hard disk is a definite option for increasing speed.

In Linux systems (specifically Fedora and Ubuntu systems), this can be achieved for Chrome and Firefox by creating a larger ramdisk, mounting the ramdisk after boot, and then setting the browser of choice to use that ramdisk as a cache. The necessary commands to do this are readily available on the internet, which makes life easy. Using ramdisks for performance boosts are not exclusive to browsers, and can be used for other software such as Nagios for example.

We have previously covered a tool called Espérance DV for moving cache to RAM in Mac OSX, and for any Windows users feeling left out, there are ways of making Firefox bend to your will. Obviously you will see an increase in RAM use (duh), but this shouldn’t be a problem unless you are running out of free RAM on your system. Remember, free RAM is wasted RAM.