DIY Foam Cutter Makes it Too Easy


Cutting foam is pretty tricky without a hot wire cutter. Don’t have one? Well, lucky for you, [Darcy Whyte] has a guide on how to make one. It takes just over an hour to build, and it costs next to nothing in supplies!

[Darcy] is using an old 9V power wart that he had lying around, but you can probably use any DC power supply. He designed the frame in SketchUp and cut it out with his CNC router, although a saw will work just as well for MDF. A piece of 40 gauge nickel chromium wire was strung taught between two 1/4-20 bolts, with one held back by a spring. The spring acts as a safeguard to prevent snapping the wire during overly aggressive cuts. This may be a simple build, but it does produce a handy tool.

[Darcy] demonstrates cutting foam with his creation in a video after the break. We think he could cut thin plastic with it as well—modify your 3D prints, anyone?—though he may need to crank up the voltage a bit.

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How to Stop Grandma’s Wheelchair If She Goes Out of RC Range

Okay, so he doesn’t have Grandma riding in it that we know of, but [zim] recently decided to turn a Jazzy mobility chair into “a radio-controlled platform for mischief”. RC offers more range than wifi or bluetooth, and he was able to find a reasonably priced secondhand radio on Craigslist. However, he found out that in the event of signal loss, the receiver keeps sending the last commands to the speed controller. [zim] didn’t want his 150 lb (68kg) mischief platform getting loose, so he devised a fail-safe that cuts power to the motor when the signal is lost.

[zim] discovered that the receiver returns channel 3 (the throttle) to a preset condition whenever the signal is lost. He used a 24V HVAC relay controlled by an Arduino Nano to sample the PW on channel 3 and shut it off when either the throttle or the signal are cut.

If Grandma is feisty, you could build this caged-in version with a shopping cart.

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Hackaday Links: January 26, 2014


The automotive industry is rolling more and more tech into their offerings. This is great for us because replacement or salvaged parts are great for projects. Here’s one component to look for. [MikesElectricStuff] tears apart the thermal imaging camera form an Audi. [via Hacked Gadgets]

Give your valentine an analog love note on the big day. [Tom's] LED heart chaser design does it without any coding. It’s a 555 timer with CD4017 decade counter. The nice thing about the setup is a trimpot adjusts the chaser speed.

[Jan] is overclocking his Arduino to 32 MHz. For us that’s kind of an “eh” sort of thing. But his statement that you need to use a clock generator because the chip won’t work with an oscillator at that frequency raised an eyebrow. We saw an AVR chip running from a 32MHz crystal oscillator in the RetroWiz project from yesterday. So do we have it wrong or does [Jan]? Share your opinion in the comments.

Download a copy of the Apple II DOS source code… legally. Yay for releasing old code into the wild! The Computer History Museum has the DOS source code and a bunch of interesting history about it. [via Dangerous Prototypes]

While we were prowling around DP for the last link we came across [Ian's] post on a new version of Bus Pirate cables. We’ve got the old rainbow cables which are pretty convenient. But if you’ve used them you’ll agree, hunting for the correct color for each connection isn’t anywhere near a fool-proof method. The new cable uses shrink tube printed with probe labels. They sound like a huge pain to manufacture. But this makes connections a lot easier. In our experience, when it doesn’t work its always a hardware problem! Hopefully this will mean fewer botched connections.

Make your tiny LiPo cells last longer. Not capacity wise, but physically. The delicate connections to the monitor PCB break easily, and the plug is really hard to connect and disconnect. [Sean] shows how he uses electrical tape for strain relief, and a bit of filing to loosen up the connector.

KerbalEdu: Kerbal Space Program for education. That’s right, you can play Kerbal as part of school now. Some may shake their heads at this, but school should be fun. And done right, we think gaming is a perfect way to educate. These initiatives must be the precursor to A Young Lady’s Illustrated Primer method of education. Right?

LittleBits Little Lathe

LittleBits Lathe

Do you need a practical, useful and fun project for a young hacker who is under your wing? How about letting them get a bit of electronics experience snapping together a LittleBits little lathe to customize their crayons. Truthfully, this isn’t much of an electronics hack, but it does make fun use of a LittleBits motor module and all those old crayons you might have lying around. You could make this a weekend project to share with the kids, plus you never know what will spark that first interest in a young engineer.

If you’re unfamiliar with LittleBits, they are small electronic modules that magnetically snap together to build larger circuits. The modules are color-coded by functionality with non-reversible magnetic connectors to help the little ones understand how to connect and integrate the modules. These LittleBits kits are great for the young beginner in electronics or just for fun at any age. Individually, the modules are quite expensive, but the parts are well worth the price because children will find the system intuitive to use and the modules are robust in the hands of careless kids. A more cost-effective purchase would be one of the kits from

In this Instructable, [maxnoble440] demonstrates the little lathe turning a crayon using a variety of tools from the very sharp to the “safe for all ages.” The geared LittleBits motor turns slowly and appears to have enough torque to carve crayons—and possibly clay—packed around a small dowel. To build this project you will need a “little bit” of wood-crafting skill to construct the mini-lathe bed. All the instructions are available in the Instructable as well as a short video, which you can watch after the break below.

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Shrinket, The Homebrew Trinket


We’ve seen a lot of Trinket builds over the past few months, but so far few people have capitalized on the Trinket’s minimalism. It’s a fairly simple circuit, as far as dev boards go, and with careful planning can be built entirely on perfboard. That’s what [villeki] did, with a project he calls Shrinket.

After looking at the schematic for the Trinket, [villeki] figured he could best the very small footprint of this ATtiny85 board. To do this, he mounted the uC on the bottom side of the board, bending the pins so they could be easily soldered to the pins. The only real challenge in building this tiny board was the USB connector. To fit this connector on board, the copper pads were carefully scraped off the protoboard and wires run to the zeniers.

The Shrinket is impressively small – only 0.6″x 0.9″ – and a very impressive example of soldering skills. If you’re looking for a project to hone your free-form soldering skills, this is a great way to spend an hour or two. Bonus, you probably already have the parts required (or a reasonable substitute) sitting around.

Copying objects in 3D


[Pulse 9] sent in a very interesting project he just finished up at an internship. It’s a 3D photocopier that scans an object and then mills said object into floral foam.

The copier is made out of material [Pulse] found sitting around – PVC, drawer slides for the X and Y axes, acrylic for the structure, and broken printer parts for the Z axis.

To scan an object, [Pulse] puts an object down on the bed and scans it with a laser and webcam. The images recorded on the camera are fed into MATLAB. The output from MATLAB is sent over serial to a custom board containing a PIC18F4620 that controls the axis motors. The spindle for this floral foam router is a simple drill; one layer at a time, the drill mills out the unneeded foam which can be sucked up by a vacuum when the object is complete.

Below you’ll find [Pulse]‘s demo of his photocopier and a piece the local news did on the project. If anyone is willing to translate that story, feel free to do so in the comments.

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12V Ammo Power Box Keeps it Retro


[Brandon Fiquett] does a lot of amateur radio communications and needed a rugged portable power supply that he could take with him on the road. He decided to make a 12V power supply out of an antique ammo can he found at an army surplus store.

The .50 cal ammo box wasn’t in the greatest condition when he picked it up, so he completely sanded it, re-painted it, and lubricated the rubber seal. Inside, he loaded it with four 7.1Ah sealed lead acid batteries, complete with 12V cigarette fused sockets, banana plug jacks, a 5V USB charger and an integrated 12V lead-acid battery charger. The lid also features an LED strip light, and everything is laid out very nicely inside of the box. It looks great, but [Brandon] has a long list of improvements to add, including a solar charge controller, volt and amp meters, and an LED power switch.

Ammo cans make solid project boxes. We’ve seen countless ammo can speaker setups, and even a more intricate ammo can PSU – though we prefer [Brandon's] method since all the connections are under the lid, keeping it completely weather proof.