Arduino-based Sieve Of Eratosthenes

October 10, 2013 by 25 Comments

ofTs7UD

[Darkmoonsinger’s] sister is finishing her graduate degree in mathematics, and [Darkmoonsinger] wanted to give her a gift that fit with her achievement. Naturally, building a Sieve of Eratosthenes using an LED matrix and an Arduino made perfect sense. If you’re unfamiliar, a Sieve of Eratosthenes is a simple, but very efficient, technique for finding prime numbers. Starting with a group of numbers, you step through each one in order. If it’s prime, you eliminate any multiples from the list. After a few iterations, the numbers remaining are all primes. After getting the LED matrix and sieve algorithm running, [Darkmoonsinger] designed an enclosure for the project. She made a couple of mistakes with this part, and happily included them for everyone’s benefit.

It only figures primes up to 64, and she lights the LED for 1 because it ‘makes the array look prettier’. Also, we couldn’t help but think that mounting the components a bit differently would have made a cleaner install (here’s a prime number generator with a backlit faceplate). However, that probably doesn’t matter to his sister. As they say, it’s the thought that counts, and we never get tired of seeing people build rather than buy!

Eidos: Audio/Visual Sensory Augmentation

October 10, 2013 by 24 Comments

eidos

One of our tipsters led us onto a very cool project by a British university team — It’s called Eidos, and it’s a real-time audio and visual augmentation system.

The creators embarked on this design journey after wondering if there was a way they could control and tune their senses. Imagine Superman and his ability to pick out one voice out of thousand — with this technology, it could be possible.

The clunky white goggles shown in the image above is the concept behind the visual augmentation. It’s akin to long-exposure photography, except that it is in real-time and is fluid video. We’re not sure how this could help anyone, but we have to admit it would be pretty cool to play around with. Maybe if Google Glass ever came out someone could write an app for it to mimic this!

The second device can target your hearing to a specific person in a noisy environment, zoning out all the unnecessary distractions. This could be very helpful for people suffering from attention deficit disorders, although we must imagine it would be very strange to get used to. Can you imagine blocking out everything and only looking at a person’s face and listening to their voice?

Unfortunately there is not much information about the actual tech or software behind these devices or if they even in fact work, but the concept was so interesting we just had to share it. Stick around after the break to see a video explanation and demonstration of the proposed technology.

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STL Fun: Converting Images To STL Geometry

October 9, 2013 by 9 Comments

stl image conversion

There’s been some good .STL manipulation tips in this week.

The first one is called stl_tools, and it’s a Python library to convert images or text to 3D-printable STL files. The examples shown are quite impressive, and it even does a top notch job of taking a 2D company logo into 3D! We can see this being quite handy if you need some quick 3D text, and either don’t use CAD, or really just need a one click solution. Now if only .STLs were easier to edit afterwards…

The second one is a Javascript based Leap Motion Controller STL manipulator, which lets you pick STLs and manipulate them individually with your fingers. If you happen to have a Leap, this could be a great way to show off 3D parts at a presentation or hackerspace talk, especially if you want to add a [Tony Stark] vibe to your presentation! Stick around after the break to see it in action — Now all we need are some good hologram generators…

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Create A Full Adder Using The C Preprocessor

October 9, 2013 by 26 Comments

Full_Adder

[Phillip] wanted to play with the C preprocessor. He decided to do that by creating a 4 bit full adder. We know this is pretty useless in everyday life, but it was a great learning experience. The beauty of this adder is right at the start. [Phillip] defines truth tables for XOR and AND. He’s able to then create strings that reference these truth tables.
For example: the first line of [Phillip’s] AND table is #define AND_00 0. If the preprocessor concatenates strings that equal “AND_00” they will then be converted to 0. This is the groundwork for the half adder .

The next step is the operational logic, which of course falls upon macros:


/* Full adder macros */
/* Out = (A ^ B) ^ cin */
#define FULL_ADD_OUT( a, b, cin ) \
 XOR( XOR( a, b ), cin )

/* Carry_out = (A & B) ^ (Carry_in & (A ^ B)) */
/* The standard adder uses OR for the last 'gate' - this
 can safely be changed  to XOR, which has been done here
 to avoid defining an OR operator */
#define FULL_ADD_CARRY( a, b, cin ) \
 XOR( AND( XOR( a, b ), cin ), AND( a, b ) )

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Making A Core Rope Read-only Memory

October 9, 2013 by 30 Comments

[Kos] tipped us about an article he made presenting his experiences in designing and implementing a core rope memory. This magnetic read-only memory (ROM), contrary to ordinary coincident-current magnetic core memories (used for RAM), uses the ferrite cores as transformers. If you look at the picture above, you’ll count 7 of them. This sets the memory word size (7bits).  A new word is added to the memory by passing (or not) a wire through the ferrite holes. If you then pass an alternating current through this wire, a current will be induced (or not) in the other wire turned 30 times around the ferrite (alias transformer secondary).

In [Kos]’s setup, an input pulse of 5V generates output pulses of 15V. For demonstration purposes, he “wrote” a simple program that lights up digits in a seven segment display. Therefore, different numbers will light up depending on which wire he uses to pass the AC current.

These days core memory hacks are few and far between. But looking at this one, and the one we saw in August, makes want more. If you know of any others don’t hesitate to send us a tip.

SCARA Arm Becomes Enormous 3D Printer

October 9, 2013 by 17 Comments

SCARA

When you find an old, disused 80s-era SCARA arm in a lab, there’s really not much more you can do than make a giant 3D printer with it.

The last time we saw [Dane]’s salvaged SCARA arm, he had reconstructed the electronics by building his own servo motor controllers and feedback sensors. There were a few initial test prints, but the new upgrades to this printer make it much more useful, make it look even more kludged together, and made the prints even more accurate.

The largest upgrade to the new machine is an updated heated build plate. The previous plate used six 30W resistors. Good enough, but with two additional 245W membrane heaters, [Dane] can now keep his build plate at a constant 65 degrees C. Keeping such a large area warm requires a heated build chamber, so [Dane] came up with a giant semi-hexagonal box of warm made from aluminum extrusion, laser-cut parts, and acrylic frames.

Compared to earlier prints, the SCARA arm is printing some very nice parts including a battery holder for 40 LiFePO4 cells, and a beautiful propeller for a 3D printed boat. It’s an impressive build, made even more so by the fact this robotic arm was found during a lab cleanup.

3D Printering: You Want UV Resin?

October 9, 2013 by 56 Comments

printering

Just a few short months ago, 3D printing with stereolithography was an uncommon and very expensive proposition. Consumer-oriented SLA machines such as the Form1 and the B9Creator are as expensive as the upper echelons of squirting plastic printers and the community behind these machines isn’t even as diverse as the forums for the fly-by-night printers featured on Kickstarter every week.

This may be about to change with last month’s reveal of the Peachy Printer, a remarkably clever stereolithography printer that requires no special equipment, hardly any electronics, and costs $100. Even if the folks behind Peachy never ship a single unit, their clever engineering ensures that stereolithography will be a staple in the makers toolbox in the near future.

There is, of course, the problem of material. While plastic filament can be bought  just about everywhere, UV curing resin is a little harder to come by and much more expensive per kilogram or liter. Where then does the stereolithography experimenter get their hands on some of this magical material from the future?

Before we get to the article…

I’ve been writing a 3D Printing column once a week for a few months now, and I’m running out of ideas. If you have something in the 3D printer world you’d like to see covered in a little more depth than the standard Hackaday post, send in a tip. I’ll send you a few Hackaday stickers if it’s a good idea.

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