Designing A Self-replicating Milling Machine

May 14, 2012 by Brian Benchoff 14 Comments

For his senior design project at Swarthmore College, [Julian] decided to build a metalworking equivalent to the RepRap. [Julian]’s final project is a self-replicating milling machine, and hopefully giving some serious metalworking power to all the makers with CNC routers and RepRaps out there.

At first glance, [Julian]’s mill doesn’t look like something you would find in a machine shop. The machine is built around a tetrahedral machine tool frame, giving the machine an amazing amount of stiffness with the added bonus of a degree of self-alignment. The spindle and motor are off-the-shelf units, but the entire bed assembly is made by [Julian] himself.

Right now, [Julian] still considers his project a very early prototype; there’s still a bit of chatter issues he’s working out, and the cost of the finished machine – about $1200, not including many hours of fine tuning – means it isn’t as competitive as other options. Still, [Julian] made a mill from scratch, and that’s nothing to scoff at.

Improving A Software Defined Radio With A Few Bits Of Wire

May 14, 2012 by Brian Benchoff 23 Comments

Impressed by the recent advances in the software defined radio scene, [Jason] picked up a $20 USB TV tuner dongle to check out his local airwaves. Unfortunately, the antenna included with the little USB dongle is terrible at receiving any signal other than broadcast TV. [Jason] wanted to improve his reception, so he got some wire and made his own discone antenna.

The discone antenna is ideally suited for [Jason]’s setup – properly constructed, it’s able to receive over the entire 64 to 1700 MHz band the RTL-SDR dongle is able to read. To construct his antenna, [Jason] checked out [VE3SQB]’s list of antenna design programs, got the dimensions of his antenna, and set to work attaching wire to PVC pipe.

The antenna is a massive improvement over the stock antenna included with the TV tuner dongle. After mounting his discone at the far end of his back yard, [Jason] started picking up a few blips from the transponders of passing aircraft.

Mapping The Motor Cortex

May 14, 2012 by Caleb Kraft 24 Comments

[Bruce] sent us another fantastic final project from the ECE4760 class at Cornell. What you see above is an array of 36 near infra red LEDs shining into this young man’s brain for the purpose of spectroscopy. Light bounces back differently based on brain activity (blood flow). For this project, they are mapping their motor cortex and displaying it on a PC using a java app. You can see the entire rig, as well as the readings in the two videos after the break.

When this tip came in, one of our writers,[Jesse Congdon], chimed in as well.

hey I actually used to work in this as an intern, at Upenn. two frequencies of near infrared light are used that both penetrate skin and bone, one bounces off of blood in general and the other bounces off oxygenated blood. Since your brain actually regulates the flow of blood to parts that are in use you can see brain activity by looking at blood flow, but then you also need to see if the brain is actually using that blood, so oxygenation gives you a full picture. The frontal cortex is a nice place to measure cause there is no hair on that portion of the skull, and it gives you emotional responses and the “aha!” moment when you figure out a problem.

One article from way back said the system was going to be used as a lie detector, since when you lie you think about the truth and the lie simoltaneously and show an increase in activity.

It’s tough though to categorize a response since you can’t really establish “base line” activity by turning off the brain

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The Making Of A Vacuum Tube

May 14, 2012 by Adam Munich 6 Comments

With the death of Heathkit looming in our minds it’s high time for a a heartwarming story. [Ronald Dekker] has done a wonderful job documenting the history of the E1T beam counting tube, detailing everything from the work led up to the invention of the tube to the lives of the inventors themselves.

For those who are unaware, the E1T is a rather strange vacuum tube capable counting from 0 to 9. While that’s nothing too special in itself, the tube also displays the numbers on a phosphor screen, much like a miniature cathode ray tube. In fact, this phosphor screen and the secondary emission caused by it is critical to the tubes operation. To put it bluntly, it’s a dekatron and a magic eye tube smashed together with the kind of love only a group of physicists could provide.

Now, who wants to have the honor of transposing Ronald’s story into a wikipedia article?

Amphi-Cycle Lets You Ride The Trails, The Waves, And Back Again

May 14, 2012 by Mike Nathan 24 Comments

amphi-cycle

Hackaday regular [Berto] is always looking for new ways to get around, and wrote in to share his most recent creation, an amphibious bicycle.

He bought an off-the-shelf inflatable boat and constructed a rig that allows him to stably mount the bike on it. Once [Berto] comes across a body of water he wants to cross, all he requires is about 7 minutes time to inflate the boat and attach his bike. Using a modified version of his electric drill-based trolling motor we saw last year, the Amphi-cycle glides across the water effortlessly as demonstrated by his assistant in the video below.

Right now the boat is propelled solely by the trolling motor and a large lead-acid battery. We would love to see the amphi-cycle powered by its rider, though we don’t know how that would affect the “one boat fits all” design [Berto] is aiming for.

Continue reading “Amphi-Cycle Lets You Ride The Trails, The Waves, And Back Again” →