Misc Hacks

4183 Articles

Bar Code Adds A Third Dimension

November 22, 2018 by 40 Comments

We never really thought about it before, but a traditional barcode or QR code is pretty two dimensional. A 3D barcode sounds like marketing hype but the JAB (Just Another Barcode) system adds a third dimension in the form of color.

Traditional barcodes assume you have a pretty crude sensor, but a color camera now days is no big deal, so why not take advantage? The JAB system specifies two types of symbols: a master symbol and a slave symbol. A master symbol has four finder patterns at the corner. Slave symbols dock to a master or another docked slave.

If you want to create some JABs, there’s a web interface. If you check advanced, you can change the number of colors used, the size of each “module” (colored box), and the width and height of the master symbol. You can also arrange for error correction. The grid that shows the master and slave symbols will allow you to click on any dockable slave location to create more symbols with different attributes.

You can then save the JAB image and use the scan menu item (at the top) to read the code back. It will also read from a camera.

If you are using a color camera and a computer or phone to read barcodes, this probably is something to check out. After all, you are acquiring color data, why not use it?

You might think of the barcode as something modern, but it has a long strange history going back to the 1930s. Early barcodes looked like bullseyes and were actually inspired by Morse code. We wonder how one of these would look on someone’s arm in ink?

See Cells In A New Light With A DIY Fluorescence Microscope

November 21, 2018 by 2 Comments

Ever since a Dutch businessman peered into the microscopic world through his brass and glass contraption in the 1600s, microscopy has had a long, rich history of DIY innovation. This DIY fluorescence microscope is another step along that DIY path that might just open up a powerful imaging technique to amateur scientists and biohackers.

In fluorescence microscopy, cells are treated with various fluorescent dyes that can be excited with light at one wavelength and emit light at another. But as [Jonathan Bumstead] points out, fluorescence microscopes are generally priced out of the range of biohackers. His homebrew scope levels the playing field a bit. The trick is to use 3D-printed parts to kit out commonly available digital cameras – a USB microscope, a DSLR, or even a smartphone camera. Excitation is provided by a ring of Nexopixel LEDs, while a movable rack holds a filter that blocks the excitation wavelength but allows the emission wavelength to pass through to the camera. He demonstrates the technique by staining some threads with fluorescent ink from a highlighter marker and placing them on a sheet of tissue paper; in conventional bright-field mode, the threads all but disappear into the background, but jump right out under fluorescence.

Ith’s true that the optics are not exactly lab quality, and the microscope is currently only set up to do reflectance imaging as opposed to the more typical transmissive mode where the light passes through the sample. That’s an easy fix, though, and reflectance mode is still useful. We’ve seen fluorescence microscopy get quite complex before, but this simple scope might be enough to get a biohacker started.

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The Lost Art Of Steam Heating

November 18, 2018 by 51 Comments

We got pointed by [packrat] to a 2015 presentation by [Dan Holohan] on the history and art of steam heating systems. At the advent of central heating systems for entire buildings, steam was used instead of water or air for the transport medium. These systems were installed in landmark buildings including the Empire State Building, which still use them to this day.

A major advantage of steam-based heating system is that no pump is required: the steam will naturally rise up through the piping, condenses and returns to the origin. This can be implemented as a single pipe where condensation returns through the same pipe as the steam, or a two-pipe system where the condensate returns through its own pipe.

In the presentation, Dan walks us through his experiences working on many of these steam heating systems in major US buildings, the types of systems, fixes implemented by engineers long since dead and the particularities of maintaining these systems.

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Magnets And Printed Parts Make Quick-Disconnect Terminals

November 15, 2018 by 19 Comments

The Apple MagSafe power connector is long gone from their product line, but that doesn’t mean that magnetic connectors aren’t without their charms. It just takes the right application, and finding one might be easier with these homebrew magnetic connectors.

We’ll admit that the application that [Wesley Lee] found for his magnetic connectors is perhaps a little odd. He’s building something called Linobyte, a hybrid art and electronics project that pays homage to computing history with very high-style, interactive core memory modules. The connectors are for the sense wire that is weaved through the eight toroids on each module, to program it with a single byte. Each connector has a 3D-printed boot that holds a small, gold-plated neodymium magnet with the sense wire soldered to it. A socket holds another magnet to the underside of a PCB. The magnet in the boot sticks to the PCB and makes contact with pads, completing the circuit. We know what you’re thinking: heating a magnet past the Curie point is a great way to ruin it. [Wesley] admits that happens, but it just makes the connection a little weaker, which works for his application. The short video below shows how he puts them together.

We can think of a couple of ways these connectors would be useful, and we really like the look of the whole project. It’ll be interesting to see where it goes, but in the meantime, brushing up on how magnets work could be fun. Continue reading “Magnets And Printed Parts Make Quick-Disconnect Terminals” →

What’s The Difference? Ask An Op Amp

November 13, 2018 by 12 Comments

If you’ve ever wondered why an op amp has the little plus and minus symbols on it, its because at the heart of it, the device is a differential amplifier. The problem is that — ideally, at least — it has infinite gain so it works like a comparator and that’s not what you usually want. So we put resistors around the thing to constrain it and get useful amplification out of it. [Stephen Mendes] does the analysis for you about how the standard configuration for a differential amplifier works. He assumes you know the stock formulae for the inverting and non-inverting amplifier configurations and uses superposition.

[Stephen] mentions that’s the easiest way to do it and then goes on to do it sort of how we would do it as a check. We think that’s the easier method, but maybe its a matter of preference. Either way, you get the right answer.

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A Fleet Of Pressure Washers Powers This Interactive Public Fountain

November 11, 2018 by 15 Comments

Public art installations can be cool. Adding in audience interactivity bumps up the coolness factor a bit. Throw civic pride, dancing jets of water, music, and lights into the project, and you get this very cool pressure washer powered musical fountain.

The exhibit that [Niklas Roy] came up with is called Wasserorgel, or “water organ”, an apt name for the creation. Built as part of a celebration of industry in Germany, the display was built in the small town of Winnenden, home to Kärcher, a cleaning equipment company best known for their line of pressure washers in the distinctive yellow cases. Eight of the company’s electric pressure washers were featured in the Wasserorgel, which shot streams of water and played notes in response to passersby tickling the sturdy and waterproof 3D-printed keyboard. The show was managed by an Arduino with a MIDI shield, which controlled the pressure washers via solid state relays and even accepted input from an anemometer to shut down the show if it got too windy, lest the nearby [Frau Dimitrakudi] be dampened.

The video below shows how engaging the Wasserorgel was during its weeks-long run in the town market square; there’s also one in German with build details. And while we can’t recall seeing pressure washers in public art before, we do remember one being used as the basis of a DIY water-jet cutter.

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Rewound And Rewired BLDC Makes A Half-Decent Generator

November 8, 2018 by 18 Comments

What’s the best way to turn a high-powered brushless DC motor optimized for hobby use into a decent low-RPM generator? Do you take a purely mechanical approach and slap a gearbox on the shaft? Or do you tackle the problem electrically?

The latter approach is what [GreatScott!] settled on with his BLDC rewinding and rewiring project. Having previously explored which motors have the best potential as generators, he knew the essential problem: in rough terms, hobby BLDCs are optimized for turning volts into RPMs, and not the other way around. He started with a teardown of a small motor, to understand the mechanical challenges involved, then moved onto a larger motor. The bigger motor was stubborn, but with some elbow grease, a lot of scratches, and some destroyed bearings, the motor was relieved of both its rotor and stator. The windings were stripped off and replaced with heavier magnet wire with more turns per pole than the original. The effect of this was to drive the Kv down and allow better performance at low RPMs. Things looked even better when the windings were rewired from delta to wye configuration.

The take-home lesson is probably to use a generator where you need a generator and let motors be motors. But we appreciate [GreatScott!]’s lesson on the innards of BLDCs nonetheless, and his other work in the “DIY or buy?” vein. Whether you want to make your own inverter, turn a hard drive motor into an encoder, or roll your own lithium battery pack, he’s done a lot of the dirty work already.

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