Building An Accurate Equal Arm Balance

August 18, 2013 by Mike Szczys 13 Comments

microscale

This interesting take on weights and measures uses a two foot long level as the base for a diy equal arm balance. The balance is the oldest method used for measuring mass. That’s because you don’t even need a reference weight for it to work as long as you are measuring ingredients that are proportional to each other in whole numbers.

The key to accuracy with these scales is to reduce friction at the fulcrum. In this case the fulcrum is made of two upturned razor blades on the base, with a single razor blade resting perpendicular to those on the arm. But because gravity is doing the equalization, the base must be as level as possible. Adjustable feet were added to the base so that it can be leveled on two axes. When the tower at the center was built (using threaded rod) a disc level was used to fine-tune the mounting angle of the two razor blades. The finishing touches include a coupling nut on each end for fine-tuning the balance, and the halves of a tea ball strainer as the weighing vessels.

Liquid Nitrogen (finally) Makes An Arduino Project Cool

August 18, 2013 by Mathieu Stephan 41 Comments

At $1.5 a liter in Moscow, [Michail] couldn’t resist buying some liquid nitrogen for himself. He thought that because Arduinos were quite popular among geeks, he’d try to overclock one while bringing its temperature down to -196°C/-320°F.

To check the ATmega was still working correctly, [Michail] designed several stability tests: SRAM read/write, flash read, arithmetic math and program flow tests (code with some conditionals). He used a standard HD44780 LCD to view the tests results but also an LED, blinking the number of the test it would have failed. The Arduino was externally clocked by a TTL-logic based square signal generator he designed, which can produce a clock between 16 and 100MHz. It turns out that you can run an Arduino at 65.3MHz when it is cooled with liquid nitrogen!

[Michail]’s article also explains what happens to the different on-board components when cooled with LN2: electrolytic capacitors becomes virtually non-existent, X7R capacitors’ impedance drop by 2/3, silicon diodes voltage drop increase by 50% and LED’s colors change. Check out the video below:

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Tearing Down An Ultrasound Machine From 1963

August 18, 2013 by Brian Benchoff 7 Comments

hehsiemens

Vintage electronics are awesome, and old medical devices doubly so. When [Murtaugh] got his hands on an old ultrasound machine, he knew he had to tear it apart. Even if he wasn’t able to bring it back to a functional state, the components inside make for great history lesson fifty years after being manufactured.

This very primitive ultrasound machine was sold by Siemens beginning in 1963 as a, “diagnostic ultrasound unit for the quick evaluation of cerebral hemorrhage after accidents.” This is barely into the era of transistors and judging from [Murtaugh]’s teardown, nearly the entire device is made of vacuum tubes, capacitors, and resistors. The only solid state component in this piece of equipment is a bridge rectifier found in the power supply. Impressive stuff, even today.

In the end, [Murtaugh] decided this device wasn’t worth repairing. There were cracks all the way through a PCB, and he didn’t have any of the strange proprietary accessories anyway. Still, this junkyard score netted [Murtaugh] a bunch of old tubes and other components, as well as a nifty CRT that came with a wonderful ‘Made in West Germany’ label,.

AquaTop: A Gaming Touch Display That Looks Like Demon Possessed Water

August 18, 2013 by Mike Szczys 9 Comments

AquaTop_touch_display Are you ready to make a utility sink sized pool of water the location of your next living room game console? This demonstration is appealing, but maybe not ready for widespread adoption. AquaTop is an interactive display that combines water, a projector, and a depth camera.

The water has bath salts added to it which turn it a milky white. This does double duty, making it a reasonably reflective surface for the projector, and hiding your hands when below the surface. The video below shows several different games being played. But the most compelling demonstration involves individual finger tracking when your digits break the surface of the water (show on the right above).

There is also a novel feedback system. The researchers hacked some speakers so they could be submerged in the tank, adding a large speaker with LEDs on it in the same manner. When fed a 50 Hz signal they make the surface of the pool dance.

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Preserve Your Garden Bounty With A Solar Food Drier

August 17, 2013 by Mike Szczys 19 Comments

solar-food-drier

The [VelaCreations] family lives off the grid, getting the electricity that they actually use from solar and wind power. When they started looking for ways to preserve the fruit and vegetables now coming into harvest the electricity consumption and cost of a food dehydrator made them balk. What they do have plenty of at this time of year is sun and heat, so they built their own solar food drier.

The frame is made of welded square tube. They mention that you will have to alter it if you don’t have welding tools, but building your own MOT welder is just one more fun project to take on. The frame has wood rails to hold the trays of food. It is enclosed with translucent polycarbonate sheets. There is a vent in the top as well as the bottom. As the heat from the sun builds inside, it flows upward, sucking fresh air in the bottom. This carries away moisture from the food and can be regulated by adjusting the size of the bottom vent.

Motorized Skateboard Controlled By Hand Gestures

August 17, 2013 by Mike Szczys 7 Comments

hand-gesture-skateboard

This rough-looking contraption is a hand gesture controlled skateboard which [Aditya] built using parts on hand. So far the sensor for hand gestures is connected by a control wire, but he hopes to transition to an RF unit at some point in the future.

Having access to a couple of high torque brushless motors is what turned him onto the project. He hit up a couple of Mechanical Engineer friends of his to help assemble the chassis and then started on the electronics side of things. A breakout board for an ATmega16 is mounted on the corner of the deck. It monitors an accelerometer which acts as steering as well as throttle. The accelerometer had been abused in a previous project so he had to add an extra switch to bolster his available inputs. We were glad to hear that he also included a kill switch, since putting the control of those motors in the hands of a damaged accelerometer is a bit sketchy.

We remember seeing a similar trike design a few years back. That one powered a single rear wheel while this one powers two wheels and uses a caster for the third.

Here Be Dragons, And VR…and Sheep.

August 17, 2013 by Marsh 7 Comments

dragonVR

This may qualify less as a hack and more as clever combination of video game input devices, but we thought it was well worth showing off. [Jack] and his team built Dragon Eyes from scratch at the 2013 Dundee Dare Jam. If you’re unfamiliar with “Game Jams” and have any aspirations of working in the video game industry, we highly recommend that you find one and participate. With only 48 hours to design, code, build assets and test, many teams struggle to finish their entry. Dragon Eyes, however, uses the indie-favorite game engine Unity3D to smoothly coordinate its input devices, allowing players to experience dragon flight. The Kinect reads the player’s arm positions (including flapping) to direct the wings for travel, while the Oculus Rift performs its usual job as immersive VR headgear.

Combining a Kinect and a Rift isn’t particularly uncommon, but the function of the microphone is. By blowing into a headset microphone, players activate the dragon’s fire-breathing. How’s that for interactivity? You can see [Jack] roasting some sheep in a demonstration video below. If you have a Kinect and Rift lying around and want some first-person dragon action, [Jack] has kindly provided a download of the build in the project link above.

We’re looking forward to more implementations of the Rift; we haven’t seen many just yet. You can, however, check out a Rift used as an aerial camera on a drone.

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