Dosimetry: Measuring Radiation

Thanks to stints as an X-ray technician in my early 20s followed by work in various biology labs into my early 40s, I’ve been classified as an “occupationally exposed worker” with regard to ionizing radiation for a lot of my life. And while the jobs I’ve done under that umbrella have been vastly different, they’ve all had some common ground. One is the required annual radiation safety training classes. Since the physics never changed and the regulations rarely did, these sessions would inevitably bore everyone to tears, which was a pity because it always felt like something I should be paying very close attention to, like the safety briefings flight attendants give but everyone ignores.

The other thing in common was the need to keep track of how much radiation my colleagues and I were exposed to. Aside from the obvious health and safety implications for us personally, there were legal and regulatory considerations for the various institutions involved, which explained the ritual of finding your name on a printout and signing off on the dose measured by your dosimeter for the month.

Dosimetry has come a long way since I was actively considered occupationally exposed, and even further from the times when very little was known about the effects of radiation on living tissue. What the early pioneers of radiochemistry learned about the dangers of exposure was hard-won indeed, but gave us the insights needed to develop dosimetric methods and tools that make working with radiation far safer than it ever was.

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When Is One Pixel Cooler Than Millions?

On vacation, we went to see a laser show – one of the old school variety that combines multiple different lasers of many different colors together into a single beam, modulates them to create different colors, and sends it bouncing off galvos to the roof of a planetarium. To a musical score, naturally.

When I was a kid, I had no idea how they worked, but laser shows were awesome. As a younger grownup hacker, and after some friends introduced me to the dark arts, I built my own setup. I now know how they work from the deepest innards out, and they are no less awesome. Nowadays, you can get a capable set of galvos and drivers for around a hundred bucks from the far east, it’s fair to say that there’s no magic left, but the awesome still remains.

RGB laser
“laser show” by Ilmicrofono Oggiono

At the same time, lasers, and laser shows, are supremely retro. The most stunning example of this hit me while tearing apart a Casio projector ages ago to extract the otherwise unobtainable brand new 455 nm blue laser diodes. There I was pulling one diode out of an array of 24 from inside the projector, and throwing away the incredibly powerful DSP processor, hacking apart the precision optical path, and pulling out the MEMS DLP mirror array with nearly a million little mirrors, to replace it with two mirrors, driven around by big old coil-of-wire electromagnets. Like a caveman.

But still, there’s something about a laser show that I’ve never seen replicated – the insane color gamut that they can produce. It is, or can be, a lot more than just the RGB that you get out of your monitor. Some of the colors you can get out of a laser (or a prism) are simply beautiful in a way that I can’t explain. I can tell you that you can get them from combining red, blue, green, cyan, and maybe even a deep purple laser.

What you get with a laser show pales in comparison to the multi-megapixel projectors in even a normal movie theater. Heck, you’ve really got one pixel. But if you move it around fast enough, and accompany it with a decent soundtrack, you’ve still got an experience that’s worth having while you still can.

[Banner image from a positively ancient RGB laser hack. We need more! Send us yours!]

Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Mad Model M

Hand-Wired Hell Help

Do you dream of building a curvy ergonomic keyboard or macro pad, even though the idea of hand wiring gives you nightmares? You can make it a bit less troublesome with a tiny PCB for each key switch, as long as you have a reflow oven or you’re okay with a bit of surface-mount soldering for the diode, LED, and capacitor.

As a bonus, these should make switches a bit more secure against movement, and you could probably even get away with using hot swap sockets if you wanted. [Pedro Barbero] has the Gerber files available if you want to get some fabbed. We sort of wish we had used these on our dactyl, though the case is awfully tight and they might not fit.

Ultra-Mechanical Keyboard Angles with Lifter Motors

Lots of people prefer an angled keyboard, but plenty of new keebs, especially mechanical ones, just don’t offer that at all. Well, the wait for an adjustable 75% is over, at least. Okay, that’s not exactly true. The wait for a group buy to begin for an adjustable 75% is almost over.

Nestled in between the arrow cluster and the menu key of the Besides Studios M-One is a rocker switch that angles the keyboard from 3° to 7° slowly but surely, like an adjustable bed. This is going to be a bare-bones group buy, meaning that it won’t come with any switches, stabs, or keycaps, but that doesn’t mean it will be cheap at $299. [BadSeed Tech] got an early prototype and built it out with Gateron Ink Black V2 switches in the video below in order to give it a proper spin.

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This Arduino Isn’t Color Blind

You can sense a lot of things with the right sensor, and [Nikhil Nailwal] is here to show us how to sense colors using a TCS230. The project is a simple demo. It displays the color and lights up an LED to correspond to the detected color.

If you haven’t seen the TCS230 before, it is a chip with an array of photosensors, for different light wavelengths. The controlling chip — an Arduino, in this case — can read the intensity of the selected color.

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An OSHW IR Remote Control Powered By The ATtiny13A

The new hotness in consumer electronics might be RF remotes based on protocols like Bluetooth Low Energy, but there’s still plenty of life left in the classic infrared remote. Especially with projects like TinyRemoteXL from [Stefan Wagner], which let you build and program an IR “clicker” of your own. Whether you want to spin up your own custom universal remote or create a beefed up version of the TV-B-Gone, this open source effort is a great place to start.

The original TinyRemote.

As you might have guessed from the name, this project is actually a larger version of the TinyRemote that [Stefan] put together previously. The documentation for that project goes a bit more into the nuts and bolts of talking IR, and is definitely worth a read if you’re into the low level stuff. For the original five button TinyRemote, the hardware consists of little more than a ATtiny13A microcontroller, a pair of IR LEDs, and the transistors to drive them.

But on the XL, things are a bit trickier as there are now twelve buttons for the ATtiny13A to read. Obviously there aren’t enough pins to read so many buttons directly, but with a combination of BAS16TW diode arrays and resistors, [Stefan] is able to detect what button was pressed using the chip’s interrupt pin and ADC. Certainly a handy trick to have in the back of your mind, and the open source nature of this project gives you a great chance to see how it’s implemented.

Between this project and the impressive development board [Djordje Mandic] released recently, it seems we’re looking at something of an infrared hacking revival. Earlier this year we even saw the commercial release of an IR-equipped ESP8266 board.

Fighting Household Air Pollution

When Kenyan engineer [Aloise] found out about the health risks of household air pollution, they knew there had to be a smart solution to combatting the problem while still providing a reasonable source of energy for families cooking without the luxury of cleaner fuels. Enter OpenHAP, a DIY household air pollution monitor that provides citizen scientists and researches the means to measure air particulates in developing countries.

The device is based on an ESP32 communicating with a ZH03B Particulate matter sensor over UART; a DS3231SN real-time clock (RTC), temperature and humidity sensor, and MLX90640 2D thermal sensor array over I2C; and wirelessly sending the data received to a Bluetooth low energy wrist-strap beacon and an Internet enabled phone. The device also uses a TCA9534 GPIO expander to control the visual and auditory notifiers (buzzers and LEDs) and to interface to a SD card.

The project uses the libesphttpd project modified for the ESP32 for the webserver, which is used to stream data to a mobile handset or computer using the WiFi capabilities of the ESP32. The data includes real-time sensor information, system status, storage media status, visualizations of the thermal array sensor data (to ensure the camera is facing the source of heat), and tag information to test the limits of the Bluetooth tag with regards to distance.

Power input is provided through a Micro-USB connector, protected with a TVS diode and a Schottky diode in series to prevent reverse power flow.

The project was tested in two real-life scenarios: one with a household in rural Kenya and another with an urban low-income family of four. In the first test, the family used a three stone open fire stove. A FLiR thermal camera captured the stove temperatures, while a standard camera was enough to capture the high levels of smoke inside the kitchen. The readings from OpenHAP were high enough to exceed the upper detection threshold for the particulate sensor, showing that the woman cooking in the house was receiving the equivalent of 8 cigarettes a day, about 8 x the WHO’s recommended particulate levels.

Within the second household, a typical energy mix of charcoal briquettes and kerosene was typically used for cooking, with kerosene used during the day and briquettes used at night. The results from measuring pollution levels using OpenHAP showed that the mother and child in the household regularly received around 1.5 x the recommended limit of pollutants, enough to lead to slow suffocation.

There’s already immense potential for this project to help researchers test out different energy sources for rural households, not to mention the advantage of having a portable low-energy pollution monitor for citizen scientists.

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Add-Ons Go Electroluminescent

It’s that time of the year again, and once more we’re faced with the latest innovations in Badgelife, the movement to explore the artistic merits of electronics and manufacturing. This is an electroluminescent printed circuit board, and it’s some of the finest work we’ve seen. It’s also a Shitty Add-On that glows blue.

The process for applying an electroluminescent coating to printed circuit boards is, surprisingly, something we’ve covered before. Late last year, [Ben Krasnow] delved deep into a DIY EL display. The process is expensive, but all the products come from a company called Lumilor. The first step in this process is applying a thin conductive coating on a substrate with an airbrush. Since the entire idea of printed circuit boards is to have a layer of conductive material etched into any shape you want, the simple circuit board is the idea experimental platform for playing with EL displays. Traditionally, EL displays were made entirely with a silk screen process, like [Fran]’s ongoing attempt to recreate the Apollo DSKY display.

The electronics for this badge are simply a Microchip MIC4832 EL Driver, which converts the 3.something volts from the add-on header into 100 or so Volts AC at hundreds of Hz. This is a single-chip solution to driving EL displays, and the only other parts you need are an inductor, diode, and a few caps and resistors. An ATtiny85 can be used to blink the circuits, or, alternatively, you could copy [Ben]’s work and build a character EL display.

The process of applying an electroluminescent coating to a PCB does require a spray gun or airbrush, and the chemicals are a bit expensive. This, though, is pushing the boundaries of what can be done with artistic PCBs. It’s new applications of technology, simply as wearable electronics. It’s the best example of the possibilities of the medium and some of the best work that’s come out of the Badgelife scene.