POV keychain from prototype to SMD board

[Augusto] wrote in to tell us about his keychain-sized persistence of vision project. He built the original prototype on some protoboard, using a PIC 16F627 to drive eight LEDs. Synchronization is managed by a tilt sensor on the board that starts the strobing to match the direction the board is traveling. This is a similar setup as the POV device that used an accelerometer, but it should be quite a bit easier to code for the tilt switch.

Once [Augusto] had the hardware dialed in he set to work laying out a surface mount design. The two AAA batteries were traded for a single 3V coin cell, which is on the back side of the board you see above. This is his first attempt at working with surface mount components and we think he did a great job. Check out the POV in action in the video after the break.

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Get out the graph paper get started on the new discrete logic contest

Here’s another chance to ply your hacking skills for cash and prizes. Dangerous Prototypes has just announced the Open 7400 Logic Competition. First prize is $100 and a bunch of hacking goodies. But even better is that since it was announced, more sponsors have stepped up to increase the kitty, and the number of entries that will get prizes.

The parameters for entry are wide open. You can design anything you want, with emphasis on originality. Make sure you take plenty of pictures and document the project along the way. Their judging will take into consideration the amount of detail posted about the project (hence the ‘Open’ in the contest title).

Need some ideas to get you started? We enjoyed the useless machine that used a 7400 NAND gate. You could always build a time piece of some sort like this no-microcontroller clock. Perhaps hardware control like this stepper motor driver is more to your liking?

[Thanks Moderboy]

Simple transistor tester makes sorting easy

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Hacker [Dino Segovis] is back with yet another installment of his Hack a Week series, and it’s looking like he isn’t too worse for wear after hunkering down to face hurricane Irene.

This week, it seems that [Dino] is having some problems separating his PNP transistors from his NPNs. After Albert Einstein proves to be less than useful when it comes to sorting electronic components, [Dino] decided to build a simple transistor tester to help him tell his PNPs and NPNs apart without having to resort to looking up product data sheets.

The tester itself is relatively simple to build. As you can see in the video below, it consists of a power supply, an LED, a few resistors, a pair of known transistors, and not much else. When everything is hooked together, the NPN/PNP pair causes the LED to light up, but the circuit is broken whenever one of the transistors is removed. Inserting a new transistor into the empty spot on the breadboard immediately lets you know which sort of transistor you have inserted.

Sure you can tell transistors apart with a multimeter, but if you have a whole drawer full of loose components, this is a far more efficient option.

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Intel’s new way of creating randomness from digital orderliness

Random number generation is a frequent topic of discussion in projects that involve encryption and security. Intel has just announced a new feature coming to many of their processors that affect random number generation.

The random number generator, which they call Bull Mountain, marks a departure from Intel’s traditional method of generating random number seeds from analog hardware. Bull Mountain relies on all-digital hardware, pitting two inverters against each other and letting thermal noise tip the hand in one direction or the other. The system is monitored at several steps along the way, tuning the hardware to ensure that the random digits are not falling more frequently in one direction or the other. Pairs of 256-bit sequences are then run through a mathematical process to further offset the chance of predictability, before they are then used as a pseudorandom number seed. Why go though all of this? Transitioning to an all-digital process makes it easier and cheaper to reduce the size of microchips.

A new instruction has been added to access this hardware module: RdRand. If it works as promised, this should remove the need for elaborate external hardware as a random number source.

[via Reddit]

Coil gun revolver

[Sam] sent in a coil gun revolver – a feature we’ve never seen on a coil gun build before. The gun is based on a cheap toy revolver and is powered by a 9 Volt battery connected to an “electrified fly swatter tennis racquet” instead of the usual disposable camera build.

The revolver mechanism isn’t perfect – [Sam] has to advance the chamber with his thumb while the capacitor is recharging. This is only because of the mechanics of the plastic toy his gun is based on, though. He figures a small motor could do the work for him, but he’ll be forgoing that project to work on the MK II version.

Most of the coil gun builds on Hack A Day have been muzzle or breech loaders, so with [Sam]‘s revolver we’re probably seeing the evolution of firearms mirrored in coil gun advancements. Does anyone want to take a guess and predict when we’ll see the equivalent of a this .50 caliber beast?. [Sam] says his next project is going to be a rifle, so he might have his work cut out for him.

Engine Hacks: Electrified Datsun is the ultimate engine swap

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Forget the Tesla Roadster, we want an electric car like [John Wayland’s] White Zombie!

If it wasn’t plastered with sponsor stickers and the like, you would never realize that this otherwise unassuming ‘72 Datsun 1200 is an absolute beast of a car. The gas engine that used to provide a mere 69 horsepower was swapped out for a pair of custom-built electric motors which propel the Datsun to 60 miles per hour in under two seconds.

The electric motors supply 500 horsepower and a staggering 1250 foot pounds of instant torque, providing one hell of a ride. The car is powered by 12 custom 29.6V battery packs which provide 2,400 Amps of current each! Aside from laying down a quarter mile in under 11 seconds, White Zombie can make a 90 mile trek before requiring a recharge.

Needless to say, this impressive car takes plenty of people by surprise each time [John] hits the track. Continue reading to watch one poor sap learn the hard way that his brand new Maserati is no match for White Zombie.

[via Discovery]

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