Hacker Builds New Single Board Computer Out of Old Single Board Computer

[Ncrmnt] had a busted tablet PC with an Allwinner A23 SoC inside. He combined two of our favorite past-times, Linux hacking and 3D printing, to make a rather sweet little single-board-computer out of it, giving the tablet a second life.

Step one was to make sure that the thing works. Normally, you’d hook up a wired serial terminal and start hacking. [Ncrmnt] took it one step further and wired in a HC-05 Bluetooth serial module, so he can pull up the debug terminal wirelessly. The rest of the hackery was just crafting a bootable SD card and poking around in the Android system that was still resident in the flash memory of the system.

Once the board was proven workable, [Ncrmnt] designed and printed a sweet custom case using Solvespace, a constraint-based 3D CAD modeler that was new to us until recently. The case (after three prints) was a perfect fit for the irregularly shaped system board, a 3.7 V LiIon battery, and a speaker. He then added some nice mounting tabs. All in all, this is a nice-looking and functional mini-computer made out of stuff that was destined for the trash. It’s fast, it’s open-source, and it’s powerful. Best of all, it’s not in the dumpster.

There are pictures and more details on his blog, as well as [Ncrmnt]’s TV-stick to computer conversion that we’ve covered before.

From Project To Kit: Instructions Are Everything

A printed copy of the instructions for our example kit
A printed copy of the instructions for our example kit

We’ve had two previous articles in this series on turning a personal electronic project into a saleable kit, in which we’ve examined the kit market in a broader context for a new entrant, and gone on to take a look at the process of assembling the hardware required to create a product. We’ve used an NE555 LED flasher as a simple example , from which we’ve gone through the exercise of setting a cost of production and therefore a retail price.

The remaining task required to complete our kit production is to write the documentation that will accompany it. These will be the instructions from which your customers will build the kit, and their success and any other customers they may send your way will hang on their quality. So many otherwise flawless kits get this part of the offering so wrong, so for a kit manufacturer it represents an easy win into which to put some effort.
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Homemade EDM Can Cut Through Difficult Materials Like Magnets With Ease

Many years ago [ScorchWorks] built an electrical-discharge machining tool (EDM) and recently decided to write about it. And there’s a video embedded after the break.

The build is based on the designs described in the book “Build an EDM” by Robert Langolois. An EDM works by creating lots of little electrical discharges between an electrode in the desired shape and a material underneath a dielectric solvent bath. This dissolves the material exactly where the operator would like it dissolved. It is one of the most precise and gentle machining operations possible.

His EDM is built mostly out of found parts. The power supply is a microwave oven transformer rewired with 18 gauge wire to drop the voltage to sixty volts instead of the oven’s original boost to 1.5kV.  The power resistor comes from a dryer element robbed from a unit sitting beside the road. The control board was etched using a hand traced schematic on the copper with a Sharpie.

The linear motion element are two square brass tubes, one sliding inside the other. A stepper motor slowly drives the electrode into the part. Coolant is pumped through the electrode which is held by a little 3D printed part.

The EDM works well, and he has a few example parts showing its ability to perform difficult cuts. Things such as a hole through a razor blade., a small hole through a very small piece of thick steel, and even a hole through a magnet.

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From Project To Kit: Getting The Hardware Right

In the previous article in this series on making a personal electronic project into a saleable kit, we looked at the broader picture of the kit market for a new entrant, the importance of gauging whether or not your proposed kit has a viable niche and ensuring that it has a good combination of buildability, instructions, and quality. In this article we will look at specifying and pricing the hardware side of a kit, illustrating in detail with an example project. The project we’ve chosen is a simple NE555 LED flasher which we haven’t built and have no intention of assembling into a kit for real, however it provides a handy reference project without the circuit itself having any special considerations which might distract from the job at hand.

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DIY Linux Computer and 6LoWPAN Gateway

We toss together our own PCB designs, throwing in a microcontroller here or there. Anything more demanding than that, and we reach for a Raspberry Pi or BeagleBone (or an old Linksys router). Why don’t we just whip together a PCB for a small Linux computer? Because we don’t know how…but [Jonas] apparently does. And when we asked him why he did it, he replied “because I can!”

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His Ethernet-to-6LoWPAN gateway project is a small, OpenWRT-capable Linux computer in disguise. Rather than yet another Raspberry Pi project, he designed around an Atmel AT91SAM9G25 400 MHz CPU, and added some memory, Ethernet, and a CC2520 radio chip to handle the wireless side. It’s all done on a four-layer board, and hotplate/skillet reflowed. This seems temptingly like something within our reach. [Jonas] had access to X-ray machines to double-check his reflow work, which probably isn’t necessary, although it looks really cool.

When finished, the project will link together a 6LoWPAN network (probably home automation) and his home wired network. That makes this device a rival to something like Philips’ Hue Bridge, which was the subject of some controversy when they locked out other devices for a few days until they recanted. Indeed, in response to this, there’s been quite a lot of effort at hacking the firmware of the Hue device, just to stay on the safe side in case Philips plays shenanigans again.

Soon, that’s not going to be necessary. [Jonas]’s design is open from the ground up, and coupled with open software running on top of the OpenWRT router operating system, that’s the full stack. And that’s great news for folks who are thinking about investing in a home automation technology, but afraid of what happens then the faceless corporations decide to pull the plug on their devices.

Electrostatic Loudspeakers: High End HiFi You Can Build Yourself

If you have an interest in audio there are plenty of opportunities for home construction of hi-fi equipment. You can make yourself an amplifier which will be as good as any available commercially, and plenty of the sources you might plug into it can also come into being on your bench.

There will always be some pieces of hi-fi equipment which while not impossible to make will be very difficult for you to replicate yourself. Either their complexity will render construction too difficult as might be the case with for example a CD player, or as with a moving-coil loudspeaker the quality you could reasonably achieve would struggle match that of the commercial equivalent. It never ceases to astound us what our community of hackers and makers can achieve, but the resources, economies of scale, and engineering expertise available to a large hi-fi manufacturer load the dice in their favour in those cases.

The subject of this article is a piece of extreme high-end esoteric hi-fi that you can replicate yourself, indeed you start on a level playing field with the manufacturers because the engineering challenges involved are the same for them as they are for you. Electrostatic loudspeakers work by the attraction and repulsion of a thin conductive film in an electric field rather than the magnetic attraction and repulsion you’ll find in a moving-coil loudspeaker, and the resulting very low mass driver should be free of undesirable resonances and capable of a significantly lower distortion and flatter frequency response than its magnetic sibling.
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Infrared Flashlight with Screen Uncovers What’s Hidden

Flashlights are handy around the house, but what if you want a stealthier approach to illuminating the night? Infrared LED flashlights can be acquired at relatively low cost, but where’s the fun in that? To that end [johnaldmilligan] spent a couple hours building an infrared flashlight-gun with an LED display to venture into the night.

[johnaldmilligan] disassembled a handheld spotlight to use as the housing, leaving the trigger assembly and 12V DC charge port in place. A miniature camera was used as the video source after removing its infrared filter. Note: if you do this, don’t forget that you will need to manually readjust the focus! The camera was mounted where LED Array Diagramthe flashlight bulb used to be instead of the LED array since the latter was impractically large for the small space — but attaching it to the top of the flashlight works just as effectively. The infrared LEDs were wired in eight groups of three LEDs in parallel to deliver 1.5V to each bank and preventing burnout. Here is an extremely detailed diagram if that sounds confusing.

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