Carrot Gun Packs A Punch; Improves Eyesight

September 4, 2012 by Mike Szczys 26 Comments

Just in time for your garden’s carrot harvest [Lou] shows us how to make a carrot firing rifle. It’s cheap, easy, and quick. If you’ve got 15 buck and 15 minutes you can have one to call your own.

The loading method is quite easy. Shove a carrot in the muzzle as far as it will go, then cut of the excess. Finish up by using a ramrod to push the carrot stub the rest of the way into the barrel. Once you’ve gnawed down the rest of the carrot nub and connected a compressor hose to the rifle you’re ready to do some damage. The video after the break shows a carrot fired all the way through a cardboard box, and penetrating a gallon jug of water.

[Lou] uses CPVC for the project. It takes just a few lengths of pipe, pipe fittings, a valve, and a threaded metal compressor fitting. After gluing everything together he threads the compressor attachment in place and heads to the firing range.

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Switch Mode Breadboard Supply From A PTH08080

September 3, 2012 by Mike Szczys 19 Comments

[Ben] wanted a switch mode power supply for his breadboard. He ordered a PTH08080 module which is made by Texas Instruments. The spec sheet would make it a great choice for him, but he was not happy to learn that the pinout doesn’t conform to the 0.1″ spacing used by solderless breadboards. His solution was to make a breakout adapter from some protoboard.

The PTH08080 can source up to 2.25A. It accepts 4.5-18V input and can output 0.9-5.5V. The best part is the efficiency that a switch mode supply achieves compared to linear regulators. This design adds in two capacitors which are suggested in the application circuit from the datasheet (PDF). Notice that there are two headers on the breakout board. One supplies power and ground to the breadboard. The other gives him a place to connect the adjustment resistor used to select the output voltage. This connects between one pin on the PTH08080 and GND. [Ben] plans to upgrade the design by included a precision trimpot for easy output voltage adjustments.

Building Your Own LED-based Home Lighting

September 3, 2012 by Mike Szczys 10 Comments

We see LEDs used in all kinds of projects but rarely does someone build a home lighting system from scratch with them. [Paulo Oliveira] decided to give the idea a try, included a fading power supply for the LEDs which he built himself. Here you can see the installation at full brightness, but his controller also offers a single lower setting.

We saw [Sprite_TM] use an RGB LED strip to light up his living room. [Paulo] went with individual LED modules instead, all the same color. They are Cree XM-L power LEDs so some thought needs to be put into heat dissipation. All six are mounted along an aluminum strip which serves as the heat sink. They’re wired in series and powered by an old laptop power supply. A PIC 12F683 uses PWM to dim the string via a MOSFET.

The control system for the two brightness levels uses the wall switch. When turned on, the LEDs fade in to full brightness. If you turn the switch off and back on before they are all the way on, the dimmed setting takes over. This was complicated by the capacitance of the PSU but [Paulo] solved that by adding a power resistor.

PIC-based USB Conversion For An NES Controller

September 3, 2012 by Mike Szczys 2 Comments

[Andres] wrote in to share his USB for NES controller project (translated). It enumerates as a USB keyboard and is easily mapped on most emulators. Over the weekend we looked in on an AVR programmer used for this purpose. [Andres] went a different direction, using a PIC microcontroller and eventually incorporating his circuit into the body of the controller.

The prototype circuit can be seen above. [Andres] uses a breakout board for the PIC 18F4550 to test the circuit. The chip has native USB support, and reading the button states from the controller’s shift register is a snap. You can see him using this test rig to play Super Mario Bros. on an emulator in the video after the break.

The second iteration of the project moves from breadboard to a soldered circuit. A 18F2550 is used as it comes in a rather small DIP package. If the legs are flattened there’s room inside the controller case for it, along with a few capacitors and a crystal. The original controller cord is removed to make way for a USB cable.

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An STM32 Processor Powers This PC

September 3, 2012 by Mike Szczys 7 Comments

This 32-bit computer is a project [Bogdan Marinescu] built as a contest entry. Sadly he didn’t win, but he did do an excellent job of documenting the build. Having seen several other home built PC projects we’re familiar with the challenges that go into such a thing, and he found some great solutions to each of them.

He started with an STM32F103ZET6 chip. This is an ARM Cortex-M3 processor which brings a lot of power to the playing field. That being said, generating a VGA signal would pretty much zap the usefulness of the chip for other processes so he offloaded that work on a separate Propeller chip. A microSD card serves as storage for the machine, which runs eLua (embedded Lua programming language). There is 1 MB of external RAM and a PS/2 port for keyboard interface. The system is networked thanks to an ENC28J60 Ethernet controller. Don’t miss the video after the break where you can see several demos running on the system.

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Steam-powered Hexapod

September 3, 2012 by Mike Szczys 25 Comments

This all-mechanical hexapod (translated) was meticulously planned and beautifully constructed. It’s not craning its neck to see what’s ahead. That’s a smoke stack for the steam engine which propels the machine.

Mechanically the legs were the hardest part. That’s only because the steam engine was not built from scratch. It’s a Wilesco D14 which is powered by solid fuel tablets. It puts out high RPM but low power so the gear ratio was set at 286:1 to make the most of its output.

The legs themselves are made of brass rods. These are anchored on one side of a larger gear, with a pivot point that allows the leg to slide vertically. The result is best seen in the clip after the break. As the drive wheel rotates, the pivot point moves the body forward until the foot is lifted by the sliding motion of the rod. It ends up looking more elegant than some of the more dexterous hexapods, but it lacks the ability to turn.

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DIY Laser Cutter From Non-DIY Parts

August 31, 2012 by Mike Szczys 20 Comments

[Jerry] missed the laser cutters he had been using at the local TechShop. It closed down and after seeing some hardware in a surplus store he decided to build a laser cutter to call his own. You won’t be disappointed by his build log. It’s got a ton of hi-res images and plenty of explanation.

Often, cost is the key consideration in these types of builds. [Jerry] spent a little more than average, but look what he got back out of it. This started as a CNC machine aimed at loading silicon wafers for a company making electron microscopes. It’s barely been used, and the light-duty specs will work just fine with a laser cutter as the gantry won’t be moving much weight or fighting the rotational force of a mill motor. He tore out the stock controllers and built his own, adding a q-switched 355nm Frequency Tripled DPSS laser along the way. We’re not quite sure what that means… but in laymen’s terms it’s an ultraviolet laser source. See the finished unit cutting out some Kapton in the clip after the break.

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