The Two Component Random Number Generator

February 10, 2014 by 41 Comments

attiny10

[Karl] was in need of a hardware random number generator, but is needs had a few caveats: it needed to be cheap, and sufficiently random. Random number generation can get quite crazy with Geiger tubes, lava lamps, and radioactive decay, but a much smaller solution was found in an 8 pin AVR microcontroller.

The solution uses AVRentropy, a library that uses the watchdog timer’s jitter in AVR microcontrollers to provide cryptographically secure random numbers. Setting up the circuit was easy – an ATtiny45 microcontroller was connected to a cheap chinese USB to serial converter. Three wires, and the circuit is complete. The code was simple as well; it’s just a call to initialize the entropy and write the bits to the serial port.

There are a few drawbacks to this build. Because the entropy library must wait until enough entropy is gathered, it can only produce about two 32-bit numbers per second. That’s all [Karl] needed for his application, though, and with an enclosure made from a wine cork and marble, he has the prettiest and smallest random number generator around.

Wow. Such Mining Rig. So Amaze.

February 10, 2014 by 67 Comments

After hearing about cryptocurrencies like Bitcoin, Litecoin, and Dogecoin, [Eric] decided he would have a go at designing his own mining rig. The goals of the project were to have a self-contained and stackable mining rig that had all the parts easily accessible. The result is this awesome computer enclosure, where GPU mining and traditional woodworking collide.

For mining all those coins, [Eric] is using five R9 280x GPUs. That’s an impressive amount of processing power that ended up being too much for the 1500W power supply he initially planned to use. With a few tweaks, though, he’s managing about 2.8 Mh/s out of his rig, earning him enough dogecoins to take him to the moon.

In the video below, you can see [Eric] building his rig out of 4×8 framing lumber. This isn’t a slipshod enclosure; [Eric] built this thing correctly by running the boards through a jointer, doing proper box joints with this screw and gear-based jig, and other proper woodworking techniques we don’t usually see.

Continue reading “Wow. Such Mining Rig. So Amaze.” →

7-Foot DIY Wind Turbine Proves Size Matters

February 10, 2014 by 15 Comments

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When [brokengun] decided to build a 7 ft diameter wind turbine, he had no idea how to even start, so he did as most of us would do and read some books on the topic. His design criteria was that it would be simple to construct and use as many recycled parts as possible. This wind turbine charges a 12 volt battery which can then be used to power a variety of gadgets.

Although made from recycled components, this isn’t a thrown together wind turbine. A lot of thought went into the design and build. [brokengun] discusses matching the blade size to that of the generator in order to maximize power and efficiency.  The design also incorporates a feature that will turn the turbine perpendicular to the wind if the wind-speed gets to high. Doing this prevents the turbine from being damaged by strong gusts.

For the main support/hub assembly, a Volvo 340 strut was used because they are widely available, cheap and known for being long-lasting. The tail boom is made from electrical conduit and it’s length is determined by the size of the main fan rotor. The tail vane is made from steel sheet metal and its surface area is also dependent on the fan rotor size to ensure that the turbine functions properly. The blades are made from wood but instead of making them himself, [brokengun] felt these were worth ponying up some cash. [brokengun] also scored a 30 ft high lattice tower an airport was getting rid of. This worked out great as it’s just the right height for a turbine of this size.

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Hack A Mag-Lite To Be Rechargeable

February 9, 2014 by 10 Comments

rechargeMaglite

Most tools sport rechargeable batteries these days, but there’s no need to toss that old flashlight: just replace the cells with rechargable ones!

[monjnoux] had a 3-cell D-sized MagLite lying around—though you could reproduce this hack with a 2 to 5 cell model—which he emptied of its regular batteries and replaced with some 11000mAh NiMHs from eBay. The original bulb was also tossed in favor of a 140-lumens LED.

After disassembling the flashlight, [monjnoux] set about installing the new parts. He replaced the original bulb with the LED, soldering it into place and securing it with hot glue. He then drilled a hole in the body of the flashlight for a DC socket. The charger he purchased is adaptive, detecting the number of cells and adjusting its voltage accordingly. It had the wrong connector, though, so [monjnoux] simply chopped off the end and soldered on a new one. For a hack that comes in at 40€, it’s definitely a cheaper alternative to the official rechargeable model: which costs 80€. And with a duration of 7 hours (though it’s unclear whether this number reflects continuous use), it likely outlasts the official model, as well.

Single Digit Numitron Clock

February 9, 2014 by 17 Comments

numitronClock

The above may look like a Nixie tube, but it’s a Numitron: the Nixie’s lower-voltage friend, and part of [pinomelean’s] single-digit Numitron clock. If you’re unfamiliar with Numitrons, we suggest you take a look at our post from a few years ago, which includes a helpful tutorial to catch you up to speed.

[pinomelean] built this little device to capture a steampunk-ish look on the cheap for a clock small enough to fit on a wrist. The build uses a PIC16F84A uC and a 4MHz crystal on a custom PCB. A small button on the side lets the wearer set the time. Similar to the Vibrating Timepiece from last month, the Numitron clock isn’t perfect, though it is more accurate: gaining only one minute every 3 days.

Check out the video after the break to see it being set and keeping track of the time. It may take a moment to understand how to read the clock, though. Each of the four LEDs indicates where the number in the Numitron tube belongs. The LEDs light in sequence from left to right, displaying the clock one digit at a time.

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Hackaday Links: February 9, 2014

February 9, 2014 by 18 Comments

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Here’s a quick tip to extend the usefulness of your multimeter. It’s a set of mini test hooks soldered to alligator clips with a short hunk of stranded wire in between. You can buy mini test hooks that go right on the metal probes of your meter, but the weight and bulk of the meter probes and cords sometimes get in the way. This rig allows more flexibility because of that wire.

Staying on the theme of test equipment tips, here’s a simple way to make a Y-connector for logic analyzers. [Thomas] uses a dual-row pin header, shorting each pair of pins so that both rows are connected. When this is plugged into a pin socket it leave two pins for connecting your test equipment and the rest of the project hardware.

After seeing our feature of a 3-wire Character LCD [Chad] wrote in to mention he built a 1-wire version using an ATmega328.

If you’re going to be in Anaheim this week you can stop by the ATX-West expo and see a 3D printer with a 1m x 1m x 0.5m printing area. [Thanks Martin]

Speaking of 3D printers, here’s a big delta robot (seven feet tall) outfitted for alternative material printing. It’s printing a CT scan of ribs and a heart in hot glue. This seems to be a popular material for more artistic uses. We just saw a hexapod which deposits hot glue as it roams.

The weaponized quadcopter post from Tuesday was a controversial one. The really bad part of it was the laser, which strapped to anything is extremely dangerous. But the other hack may have just been poorly executed. Hackaday alum [Jeremy Cook] wrote in to mention that fireworks and quadcopters can be used more responsibly. He strapped a sparkler to his quadro and used it to make light graffiti. You may remember that [Jeremy] wrote an introduction to light graffiti for us back in November.

Hack All The Things In The Time You Save With This LED Pomodoro Timer

February 9, 2014 by 36 Comments

Do you want to use your time more productively but are tomato-averse? [Robin]’s LED Pomodoro timer could be the perfect hack for you.

The Pomodoro Technique is a time management solution developed in the late 1980s. The basic idea is to spend a very focused 25 minutes performing some activity such as working or studying and then take a 5-minute break. Many of its proponents use a tomato-shaped kitchen timer to alert them to switch between the two states, but [Robin] wanted to make his own and learn along the way.

First, he wanted to use an ATtiny85 and learn about its features. Specifically, he used its timers, PWM, and low-power sleep mode. [Robin] used Charlieplexing to drive a total of six LEDs. When the timer starts, five yellow LEDs are driven high to indicate each 5-minute slice of work time. A red LED is lit during the 5-minute break.

[Robin] also explored compact PCB design and fabrication. All components are SMD and his board is 4cm square. [Robin] is using this SMD buzzer for discrete feedback. He included a footprint for a six-pin ISP header and programmed it with pogo pins. The timer is completely interrupt-driven: one click of the tactile button starts the work counter, and the buzzer sounds when time is up. A second click starts the break counter.

[Robin] has made everything available in his GitHub repo and encourages you to use it. Time’s a-wastin’!