LED Tester Royale

January 29, 2016 by 33 Comments

What do you get for the geek who has everything and likes LEDs? A tricked-out LED tester, naturally. [Dave Cook]’s deluxe model sports an LCD screen and two adjustable values: desired current and supply voltage. Dial these in, plug in your LED, and the tiny electronic brain inside figures out the resistor value that you need. How easy is that?

An LED tester can be as easy as a constant-current power supply, and in fact that’s what [Dave]’s first LED tester was, in essence. Set an LM317 circuit up to output 10mA, say, and you can safely test out about any LED. Read off the operating voltage, subtract that from the supply voltage, and then divide by your desired current to figure out the required resistor. It only takes a few seconds, but that’s a few seconds too many!

The new device does the math for you by adding an AVR ATtiny84 into the mix. The microcontroller reads the voltage that the constant current supply requires, does the above-mentioned subtraction and division, and displays the needed resistor. So simple. And as he demonstrates in the video below, it does double-duty as a diode tester.

This is a great beginner’s project, and it introduces a bunch of fundamental ideas: reading the ADC, writing to an LED screen, building a constant current circuit, etc. And at the end, you have a useful tool. This would make a great kit!

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Back To The Drawing Board

January 28, 2016 by 26 Comments

Ever try signing your name with a mouse or a trackball? Not so easy. You could buy a graphics tablet with a pen. [Rahul Ramakrishnan] has a different approach. He took two 10-turn pots, and attached some strings and a washer. A pencil goes through the washer, and a BeagleBone Black reads the pots to determine what it is drawing on the paper. A couple of retractable badge lanyards keep tension on the string.

This ingenious design would be easy enough to replicate with any microcontroller that can read the two pots. The only awkward part is the need to press a button down when you want the device to treat the pencil as down (see the video below). It would probably be easy to rig up some switch on the pencil to make operation a little smoother.

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Ford Explorer Lives Again As A Jurassic Truck

January 28, 2016 by 24 Comments

After Jurassic World came out and interest in Jurassic Park took off, [Voicey] decided he just had to make his very own Jurassic Park tour vehicle. Only problem? He lives in the UK and Ford Explorers aren’t exactly common there.

Wanting to keep it as movie-accurate as possible, he knew he had to get a first generation Explorer, and luckily, he managed to find one on an American car Facebook page. He bought it and got to work.

The first step was building custom bumper and brush guards, which he re-purposed from a Land Rover. Then he had a lot of painting to do. A lot.

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Hacking A Coffee Machine

January 28, 2016 by 19 Comments

The folks at Q42 write code, lots of it, and this implies the copious consumption of coffee. In more primitive times, an actual human person would measure how many cups were consumed and update a counter on their website once a day. That had to be fixed, obviously, so they hacked their coffee machine so it publishes the amount of coffee being consumed by itself. Their Jura coffee machine makes good coffee, but it wasn’t hacker friendly at all. No API, no documentation, non-standard serial port and encrypted EEPROM contents. It seems the manufacturer tried every trick to keep the hackers away — challenge accepted.

The folks at Q42 found details of the Jura encryption protocol from the internet, and then hooked up a Raspberry-Pi via serial UART to the Jura. Encryption consisted of taking each byte and breaking it up in to 4 bytes, with the data being loaded in bit positions 2 and 5 of each of the 4 bytes, which got OR’ed into 0x5B. To figure out where the counter data was stored by the machine in the EEPROM, they took a data dump of the contents, poured a shot of coffee, took another memory dump, and then compared the two.

Once they had this all figured out, the Raspberry-Pi was no longer required, and was replaced with the more appropriate Particle Photon. The Photon is put on a bread board and stuck with Velcro to the back of the coffee machine, with three wires connected to the serial port on the machine.

If you’d like to dig in to their code, checkout their GitHub repository. Seems the guys at Q42 love playing games too – check out 0h h1 and 0h n0.

Thanks [Max] for letting us know about this.

The Flowing Pixels Of Time Wait For No Man

January 28, 2016 by 14 Comments

The hourglass dramatically depicts the flow of time; gravity pulling grains of sand inevitably downward. So it is with the Bits of Time project by [Frank Andre]. The pixels drop, stopping only when the battery dies. Or, when your eggs are ready. (Pssst, it’s also on Hackaday.io.)

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Look, Ma! No GIF!

The project starts with a couple of [Frank’s] PixBlocks. A processor is added to one PixBlock to serve as the controller for both after they are connected via the serial bus. A tilt switch, with a debouncing circuit, is connected to an IO pin. This tells the processor the orientation of the box and therefore which way the pixels should flow.

Two  switches set the duration of the timer in 15 second increments. A third starts the timer. When the box is rotated the pixels start flowing in the opposite direction. With code available on GitHub the system can be programmed for other effects such as changing colors, flickering, or even text display.

You’ll agree this is a bit less intimidating than the MacGyver-ish kitchen timer we covered last year.

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Super Slick, Super Portable Styrofoam Slicer

January 28, 2016 by 12 Comments

[The King of Random] always seems to have something fun going on in his shop, and his builds tend to be impressively complete. No exception to that rule is his recent hot-wire foam cutter that looks like a ton of fun both to build and to use.

Starting with a simple PVC tubing frame to form the bow of the cutter, the rig ends up looking a little like a scroll saw when [Random] is done with it. A generous work surface sits atop a wood frame, which houses the electrics. A light dimmer and step-down transformer control the cutting wire’s temperature, and the bow even pivots to allow the wire to make miter cuts. A nice final touch is that the frame holding the bow detaches from and store inside the base, making the whole thing portable. It even runs off solar or batteries if you need to work off-grid, which might be handy for quick repairs on the R/C flight line.

Speaking of R/C, check out these hot-wire cut foam airplane wings. And the completeness of this build gets us thinking about the potential for CNC foam cutters.

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The Price Of Space

January 28, 2016 by 61 Comments

Many engineers of a certain age have one thing in common: Their early interest in science and engineering came from watching the US and Russian space programs. To me, regardless of any other benefit from the space program (and there are many), that ability to inspire a future generation of engineers made the entire program worthwhile.

We live in a world where kids’ role models are more likely to be sports or entertainment figures that have regular visits to police stations, jails, and rehab centers. The value of having role models that “do science” is invaluable.

This time of the year is a dark time for NASA missions, though. On January 27, 1967, the Apollo I crew (Grissom, White, and Chaffee) died in a fire. The investigation led to NASA limiting how much Velcro you can use in a cabin and moving away from pure oxygen in the cabin.

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