Fail Of The Week: How Not To Build Your Own Motorcycle

There’s a saying among writers that goes something like “Everyone has a novel in them, but in most cases that’s where it should stay”. Its source is the subject of some dispute, but it remains sage advice that wannabe authors should remember on dark and stormy nights.

It is possible that a similar saying could be constructed among hackers and makers: that every one of us has at least one motor vehicle within, held back only by the lack of available time, budget, and workshop space. And like the writers, within is probably where most of them should stay.

[TheFrostyman] might have had cause to heed such advice. For blessed with a workshop, a hundred dollars, and the free time of a 15-year-old, he’s built his first motorcycle. It’s a machine of which he seems inordinately proud, a hardtail with a stance somewhere closer to a café racer and powered by what looks like a clone of the ubiquitous Honda 50 engine.

Unfortunately for him, though the machine looks about as cool a ride as any 15-year-old could hope to own it could also serve as a textbook example of how not to build a safe motorcycle. In fact, we’d go further than that, it’s a deathtrap that we hope he takes a second look at and never ever rides. It’s worth running through some of its deficiencies not for a laugh at his expense but to gain some understanding of motorcycle design.

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Parallel Compressors For Sandblasting Without Crashing Your Grid

[Hannah] is restoring a 1962 Volkswagen Bug. The goal is to get the car on the road in time for her driver’s test. This is no easy task, as the lower 3 inches of all the body work is rusted out, and the engine is…. well, missing. Basically, the car needs a frame off restoration. This means that [Hannah] will have a lot of metal bodywork to clean up. One of the easiest ways to do that is sandblasting.

Large scale sandblasting is a bit different from most air-powered operations. Sandblasting needs only a modest air pressure, but a high air flow. [Hannah] need 25 Sustained Cubic Feet Per Minute (SCFM) at 80 PSI for sandblasting. Most compressors can easily supply that pressure, but 25 SCFM is asking quite a lot. She could go with an expensive 3 phase unit, or rent a diesel screw compressor. However, [Hannah] decided to connect 4 compressors in parallel to give her the flow she needed.

Connecting the air outputs in parallel is easy. The problem is the electricity. Each compressor is rated for 9 amps while running. They draw quite a bit more while starting up. The compressors have to be wired to individual 15 amp circuits to avoid blowing fuses. They also need to be started in sequence so they don’t pull down the AC for the entire house while starting.

Hannah could have used any sort of delay for this, but she chose an Arduino. The Arduino’s wall wart is wired up to the master compressor. Turning on the master powers up the Arduino which immediately starts a 2 second delay. When the delay times out, the Arduino fires up the second compressor. After several delay loops, all 4 compressors are running together.

hannah-schThe Arduino’s GPIO pins can’t handle 9 amp AC loads, so [Hannah] wired them to TIP120 transistors. The TIP120s drive low power relays, which in turn drive high current air conditioning relays. The system works quite well, as can be seen in the video below the break.

If you’re interested in air compressor projects, check out this setup made from an old refrigerator compressor. For more background on the TIP120, check out this article about these useful transistors.

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History Of The Capacitor – The Pioneering Years

The history of capacitors starts in the pioneering days of electricity. I liken it to the pioneering days of aviation when you made your own planes out of wood and canvas and struggled to leap into the air, not understanding enough about aerodynamics to know how to stay there. Electricity had a similar period. At the time of the discovery of the capacitor our understanding was so primitive that electricity was thought to be a fluid and that it came in two forms, vitreous electricity and resinous electricity. As you’ll see below, it was during the capacitor’s early years that all this changed.

The history starts in 1745. At the time, one way of generating electricity was to use a friction machine. This consisted of a glass globe rotated at a few hundred RPM while you stroked it with the palms of your hands. This generated electricity on the glass which could then be discharged. Today we call the effect taking place the triboelectric effect, which you can see demonstrated here powering an LCD screen.

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A Very Modern Turing Machine Build

Mathematicians. If you let them use the concept of infinity, there’s almost nothing they won’t be able to prove. Case in point: the Turing machine. The idea is that with an infinite length of tape, one could build a thought-experiment machine with only a few instructions that should be able to compute anything that’s computable.

[Igor]’s Turing machine is one of the nicest we’ve ever seen built. The “tape” is significantly shorter than infinity, which limits the computations he can achieve, the use of 3D printing, electric contacts, and WS2812 RGB LEDs for the tape are profoundly satisfying.

A bit on the tape is portrayed as unused if the LED is off, zero if it is red, and one if it is green. Each station on the tape is indexed by a set of blue LEDs observed by the gantry of the writing head which uses a 3D printed finger and motor to change the state of each bit. Programs are stored on a home-built punch card, which gets extra geek points from us.

Watch it run through “busy beaver” (embedded below) and tell us that it’s not awesome, even if it is a couple of LEDs short of infinity.

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I2C Bit Injection Adds Memory Banks To Everything

[Igor] wished to upgrade his newly acquired radio — a Baofeng UV-82 — with a larger memory for storing additional scanning channels, and came up with a very elegant solution: Replacing it’s EEPROM with a larger one and injecting the additional memory address bits into the I2C data line.

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Hackaday Prize Entry: MiniSam-Zero

Thanks to the Arduino, Atmel’s SAM line of ARM microcontrollers are seeing a lot of use as 32-bit learning tools. For his Hackaday Prize project, [Jeremey] is using one of these chips without all the Arduino drama. He’s built a tiny Atmel SAM dev board that’s cheap, simple, and interestingly for a 32-bit ARM board, easy to program.

For this board, [Jeremy] is using Atmel’s SAM D09, the smallest member of the family that also includes the chip on the new Arduino Zero and the Arduino M0 (built by the other Arduino). The MiniSam-Zero uses a slightly smaller chip with 8 kB of on-chip Flash. Eagle-eyed complainers will notice the SAM D09 does not have internal EEPROM, so an EEPROM is added on-board. Also on board is a temperature sensor and a Silicon Labs CP2102 for serial communications.

That last chip – the Serial USART – allows for a rather interesting build if the firmware is done right. Instead of futzing about with ARM SWD while programming the device, a serial bootloader would allow anyone to plug a USB cable into this board and upload code straight from an IDE. This is perhaps the coolest feature of the MiniSam-Zero, and something [Jeremy] has worked tirelessly to get right. He can upload directly from Atmel Studio, and after a bit more work, [Jeremy] will be able to program this board directly from the Arduino IDE. That’s great work, and although this board isn’t as capable as other ARM microcontroller offerings, it’s still a fantastically useful device.

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TritiLED Lights Up The Night, Doesn’t Make You Glow

Tritium, or 3H is an isotope of hydrogen which has been used as everything from radiolabel in analytical chemistry to a booster to kickstart the chain reaction of nuclear weapons. Lately tritium’s most common use has been in key chains and jewelry. A small amount of tritium is stored in a phosphor coated glass tube. The beta decay of the tritium causes the phosphor to glow. The entire device is called a Gaseous Tritium Light Source (GTLS).

In the USA, GTLS devices are only allowed to be used in specific cases such as watches, compasses, and gun sights (MURICA!). Key chains and jewelry are considered frivolous uses and are prohibited by the nuclear regulatory commission. Of course, you can still order them from overseas websites.

The safety of GLTS devices have been hotly debated on the internet for years. They’re generally safe, unless you break the glass. That said, we’re happy getting our radiation exposure through cool hacks, rather than carrying a low-level source around in our pockets.

Enter [Ted Yapo], an amateur astronomer. After tripping over his telescope tripod one time too many, he decided to take matters into his own hands. He’s designing TritiLED, a dim LED light source which can last for years. [Ted] is using a  Luxeon Z LED, driven with PWM by a PIC 12F508 8 bit microcontroller. Running at 26.3 μA, he estimates about a year of run time on a CR2032 watch battery, or a whopping 15 years on a pair of lithium AA cells. Sure he could have done it with a 555 timer, but using a micro means more features are just a few lines of code away. [Ted] took advantage of this by adding a high brightness mode, blink modes, and an exponential decay mode, which emulates the decay of GLTSs.

Best of all it’s all open source. [Ted] is publishing under the (CC-BY-SA) license on Hackaday.io.