Tic Tac Clock

June 22, 2014 by 8 Comments

tic-tac-clock

Here’s an excuse to eat a bunch of Tic Tac candies: once the container is empty it makes a nice little enclosure for your next project. This particular offering introduces a point-to-point clock project that’s a ton of fun.

[Danny Chouinard] did a lot with very little. You can get the gist of the circuit just by looking at the photos above. it uses a 3×5 Charlieplexed LED display (this is given away by the fact that there’s only a few resistors on the board. A bit difficult to see, but between the resistors and the ATtiny84 there is a clock crystal, and on the back is a little piezo buzzer. The one thing that isn’t completely obvious is the power source. Two AAAA batteries, salvaged from a 9V battery, are able to keep the unit running at an estimated 2 years of moderate use.

The video after the break is worth a look though. It shows the various characters and information that can be flashed on the LED matrix. At first it’s hard to tell that the single user input button is being pressed by [Danny’s] thumb.

If you don’t want to build a clock, there are still plenty of reasons to eat a whole container of these mints. You could replace them with a PIC programmer or a discreet camera.

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Wooden Band Saw Fears Its Wood-Cutting Brethren

June 22, 2014 by 18 Comments

DIY Wooden Bandsaw

What is cooler than building a band saw out of wood? Building two, of course! And that is exactly what [Pekka] did. The first was a small bench top model while the second was a much larger version with the saw blade strung between big 13-3/4 inch wheels. For those who are unfamiliar with band saws, they are tools that have a long thin blade that is routed around rotating wheels. The wheels are spread apart to make the blade taut. Unlike the reciprocating action of a jigsaw, saws-all or scroll saw, the band saw blade continually rotates in one direction. These blades are typically thin making it easy to cut irregular and curved shapes.

The frame of [Pekka’s] larger machine is made from 35mm (~1-3/8″) plywood. This proved to be a sturdy frame material. The previously mentioned wheels were made by gluing pieces of oak together, mounting the assembly on a wood lathe and turning the outer diameter down to size. By using multiple piece of wood to construct the wheels allows the grain direction of each portion to be parallel with the blade. This method of construction ensures any expansion/contraction of the wood is uniform around the wheel. A strip of rubber around the blade’s outer diameter provides the friction required to prevent the blade from slipping.

[Pekka’s] friend was nice enough to turn the flanged axle shafts on his metal lathe. These shafts support the wooded wheels and are mounted in pillow block bearings. The upper pillow blocks are mounted to a sliding support that allows adjusting the tension of the saw blade. [Pekka] was not going to be satisfied with a one-speed band saw so he grabbed a motor he had kicking around that originally came from a wood lathe and already had 4 different sized pulleys mounted on the shaft.

This is a great project that shows what can be done with a little desire and ingenuity.

CNC Plasma Cutter Build Presented In Excruciating Detail

June 22, 2014 by 18 Comments

If you have been wondering what it takes to build a CNC Plasma Cutter then get ready to look no further. [Desert Fabworks] has documented the trials and tribulations of their CNC Plasma Cutter build. Saying it is extremely detailed would be an understatement. They cover everything from choosing components to machine setup.

The group already had a CNC Plasma Cutter that they have outgrown. To justify the new purchase the replacement machine would have to have a few non-negotiable features: 4×8 ft cutting area, torch height control, water table, cutting up to 1/2″ steel and be easy to operate and maintain. For the frame and gantry, they settled on a Precision Plasma kit as they felt it was the best value that met their requirements. The electronics package was separate from the frame kit and was provided by CandCNC. Among other things, this package included the power supply, stepper motors, stepper drivers and the torch height controller. For the plasma cutter itself [Desert Fabworks] chose a Hypertherm Powermax65 which can cut up to an inch thick of mild steel and has swappable torches so the main unit can be used for both the CNC table and hand cuts.

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Converting CTs And MRIs Into Printable Objects

June 22, 2014 by 15 Comments

People get CT and MRI scans every day, and when [Oliver] needed some medical diagnostic imaging done, he was sure to ask for the files so he could turn his skull into a printable 3D object.

[Oliver] is using three different pieces of software to turn the DICOM images he received from his radiologist into a proper 3D model. The first two, Seg3D and ImageVis3D, are developed by the University of Utah Center for Integrative Biomedical Computing. Seg3D stitches all of the 2D images from an MRI or CT scan into a proper 3D format. ImageVis3D allows [Oliver] to peel off layers of his flesh, allowing him to export a file of just his skull, or a section of his entire face. The third piece of software, MeshMixer, is just a mesh editor and could easily be replaced with MeshLab or Blender.

[Oliver] still has a lot of work to do on the model of his skull – cleaning up the meshes, removing his mandible, and possibly plugging the top of his spinal column if he would ever want to print a really, really awesome mug. All the data is there, though, ready for digital manipulation before sending it off to be printed.

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The Beginning Of The Age Of 3D Resin Printers

June 21, 2014 by 23 Comments

resin

For several years now, filament-based plastic printers have ruled the hobbyist market, with a new iteration on squirting plastic appearing on Kickstarter every week. SLA printers, with their higher resolution and historically higher price for raw materials, have sat in the background, waiting for their time to come.

Now, with the Sedgwick printer now available on Kickstarter, we may finally be seeing some resin printers make their way into hackerspaces and workshops the world over. Instead of other DLP projector-based resin printer where projector light shines up through the resin tank, the creator of the Sedgwick, [Ron Light] is doing things the old-fashioned way: shining the projector down onto the surface of the resin. He says it’s a simpler method, and given he’s able to ship a Sedgwick kit minus the projector for $600, he might be on to something.

There are a few other resin printers coming on the scene – the LittleSLA will soon see its own Kickstarter, the mUVe 1 is already shipping, and over on Hackaday Projects, the OpenExposer project is coming along nicely. All very good news for anyone who wants higher quality prints easily.

(Better) Full Motion Video On The First PC

June 21, 2014 by 42 Comments

Ladies

Ten years ago, [Trixter] created 8088 Corruption, a demo for the original PC, the IBM 5150, that displayed full motion video using a CGA card and a SoundBlaster. It was hailed as a marvel of the demoscene at the time, garnered tons of hits when it was eventually uploaded to Google Video, and was even picked up by the nascent Hackaday.Now, ten years later, and seven years after [Trixter] said full motion video using the graphics mode of a CGA adapter was impossible, he’s improved on his earlier work. Now, it’s possible to display video at 640×200 resolution at 30 frames per second on a 30-year-old computer.

[Trixter]’s earlier work used the text mode of the CGA adapter, only because the 40×25 character, 16 color mode was the only graphics mode that could be entirely updated every single frame. It’s still one of the high points of the PC demoscene, but from the original video, it’s easy to see the limitations.

A while back, [Trixter] said displaying video using his computer’s graphics mode was impossible. He’s had years to think about this statement, and eventually realized he was wrong. Like the developers of modern video codecs, [Trixter] realized you don’t need to change every pixel for every frame: you only need to change the pixels that are different from frame to frame. Obvious, if you think about it, and all [Trixter] needed to do was encode the video in a format that would only change dissimilar pixels from frame to frame, and manage the disk and memory bandwidth.

After reencoding the 10-year-old demo for graphics mode, [Trixter] turned toward his most ambitious demo to date: playing the ‘Bad Apple’ animation on an 8088. As you can see in the video below, it was a complete success.

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Delving Deep Into High Speed Digital Design

June 21, 2014 by 29 Comments

scope capture showing ringing affect in a high speed digital signal

In high speed digital circuits, fast doesn’t necessarily mean “high clock rate”. [Jack Ganssle]  does an excellent job at explaining how the transition time of signals in high speed digital circuits is just as important as the speed of the signal itself. When the transition time is large, around 20 nanoseconds, everything is fine. But when you cut it down to just a few nanoseconds, things change. Often you will get a ringing effect caused by impedance mismatch.

As the signal travels down the trace from the driver and hits the receiver, some of the signal will get reflected back toward the driver if the impedance, which is just resistance with a frequency component, does not exactly match. The reflected signal then heads back to the driver where the impedance mismatch will cause another reflection. It goes back and forth, creating the ‘ringing’ you see on the scope.

[Jack Ganssle] goes on to explain how a simple resistor network can help to match the impedance and how these should be used in circuits with fast transition times, especially where you will be taking readings with a scope. As the scope probe itself can introduce impedance and cause the ringing.

In case you didn’t pick up on it, [Jack Ganssle] also happens to be one of the judges for The Hackaday Prize.

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