Last chance to enter The Hackaday Prize.

Laser Piano Worthy Of The Band ‘Wyld Stallyns’

Laser Piano uses Arduino

[Robi] and [Kathy] from elecfreaks have put together a how-to article about a Laser Piano they just built. Instead of keys, the user breaks beams of laser light to trigger the sounds.

Several laser pointer diodes are wired in parallel and mounted in a box, cardboard in this case. The laser diodes are aimed at photocells that reside on the other side of the box. Each photocellis connected to a digital input pin on an Arduino. When the Arduino senses a state change from one of the photocell, meaning the beam of light has been interrupted, it plays the appropriate wave file stored on an external JQ6500 sound module.

[Robi] admits that there are some improvements to be made, specifically the trigger response time and the piano sounding too monotonous. If you have any ideas, please leave them in the comments section.

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The Old Ping-Pong Ball Levitation Trick

pingpongLev

[Jacob] has put a slightly new twist on the levitating ball trick with his ping-pong ball levitation machine. We’ve all seen magnetic levitation systems before. Here on Hackaday, [Caleb] built a Portal gun which levitated a Companion Cube. Rather than go the magnetic route, [Jacob] levitated a ping-pong ball on a cushion of air.

Now, it would be possible to cheat here, anyone who’s seen a demonstration of Bernoulli’s principle knows that the ball will remain stable in a stream of air. [Jacob] proves that his system is actually working by levitating ping-pong balls with different weights.

A Parallax Ping style ultrasonic sensor measures the distance between the top of the rig and the levitating ball. If the ball gets above a set distance, [Jacob's] chipKit based processor throttles down his fans. If the ball gets too low, the fans are throttled up. A software based Proportional Integral Derivative (PID) loop keeps the system under control. A graph of the ball distance vs fan speed is displayed on an Android tablet connected to the controller via USB.

When [Jacob] switches a heavy ball for a light one, the lighter ball is pushed beyond the pre-programmed height. The controller responds by reducing the fan speed and the ball falls back. Who said you can’t do anything good with a box of corn dogs?

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Don’t Freak Out — Your TODO List for August 4th

The registration cut-off for The Hackaday Prize is August 4th. But this is not the day you need to have your project finished. You simply need to register your concept before the cutoff. This video walks you through the process, and we’ve included bullet points and links after the break for your convenience.

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Pocket Calculator Emulates Pocket Calculator

msp430 Calc Emu

[Chris] has built a pocket calculator that emulates… a pocket calculator. Two pocket calculators, in fact. Inspired by [Ken Shirriff's] incredible reverse engineering of the Sinclair scientific calculator, [Chris] decided to bring [Ken's] Sinclair and TI Datamath 2500II simulators to the physical world.

Both of these classic 70’s calculators are based on the TMS0805 processor. The 0805 ran with 320 11-bit words of ROM and only three storage registers. Sinclair’s [Nigel Searle] performed the real hack by implementing scientific calculator operations on a chip designed to be a four function calculator.

[Chris] decided to keep everything in the family by using a Texas Instruments msp430 microcontroller for emulation. He adapted [Ken's] simulator code to run on a MSP430G2452. 256 bytes of RAM and a whopping 8KB of flash made things almost too easy.[Chris'] includes ROMs for both the TI and the Sinclair calculators. The TI Datamath ROM is default, but by holding the 7 key down during boot, the Sinclair ROM is loaded. The silk screen includes key icons for both calculators, as well as some Doge-inspired wisdom on the back.

All joking aside, these really are amazing little calculators. Children of the 60’s and 70’s will be taken back when they see the LEDs flash as the emulated TMS0805 performs algorithmic arithmetic. [Chris'] code is up on Github. While he hasn’t released gerbers yet, he does have images of his PCB layout on the 43oh.com forums.

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THP Entry: A Repurposed Luminiferous Aether Detector

laserIn the late 1800s, no one knew what light was. Everyone knew it behaved like a wave some of the time, but all waves need to travel through some propagation medium. This propagation medium was called the luminiferous aether and an attempt to detect and quantify this aether led to one of the coolest experimental setups of all time: the Michelson-Morely experiment. It was a huge interferometer mounted on a gigantic slab of marble floating in a pool of mercury. By rotating the interferometer, Michelson and Morely expected to see a small phase shift in the interferometer, both confirming the existence of a luminiferous aether and giving them how fast the Earth moved through this medium.

Of course, there was no phase shift, throwing physics into chaos for a few years. When [Beaglebreath] first learned about the Michelson-Morely interferometer he was amazed by the experimental setup. He’s built a few interferometers over the years, but for The Hackaday Prize, he’s making something useful out of one of these luminiferous aether detectors: a functional laser rangefinder capable of measuring distances of up to 60 inches with an error of 0.000005 inches.

The core of the system is an HP 5528A laser interferometer system. [Beaglebreath] has been collecting the individual components of this system off of eBay for several years now, and amazingly, he has all the parts. That’s dedication, right there. This laser interferometer system will be mounted to a simple camera slider, and with the interferometer measurements, humidity and temperature measurements, and some interesting code (running on one of these for hacker cred), [Beaglebreath] stands a good shot at measuring things very, very accurately.

The devil is in the details, and when you’re measuring things this precisely there are a lot of details. The original Michelson-Morely interferometer was affected by passing horse-drawn carriages and even distant lightning storms. While [Beaglebreath] isn’t using as long of a beam path as the OG interferometer, he’ll still have a lot of bugs to squash to bring this project to its full potential.


SpaceWrencherThe project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.

Developed on Hackaday: Demonstration Video and Feedback Request

For months our dear Hackaday readers have been following the Mooltipass password keeper’s adventures, today we’re finally publishing a first video of it in action. This is the fruit of many contributors’ labor, a prototype that only came to be because of our motivation for open hardware and our willingness to spend much (all!) of our spare time on an awesome project that might be just good enough to be purchased by others. We’ve come a long way since we started this project back in December.

In the video embedded above, we demonstrate some of our platform’s planned functionalities while others are just waiting to be implemented (our #1 priority: PIN code entering…). A quick look at our official GitHub repository shows what it took to get to where we are now. What’s next?

We need your input so we can figure out the best way to get the Mooltipass in the hands of our readers, as our goal is not to make money. The beta testers batch has just been launched into production and I’ll be traveling to Shenzhen in two weeks to meet our assembler. When materials and fabrication are taken into account we expect each device to cost approximately $80, so please take 3 seconds of your time to answer the poll embedded below :

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