A square PCB with a Raspberry Pi Pico mounted in the middle

Identify Radioactive Samples With This DIY Gamma-Ray Spectrometer

May 3, 2022 by Robin Kearey 37 Comments

If you’re a radiation enthusiast, chances are you’ve got a Geiger counter lying around somewhere. While Geiger counters are useful to detect the amount of radiation present, and with a few tricks can also distinguish between the three types of radiation (alpha, beta and gamma), they are of limited use in identifying radioactive materials. For that you need a different instrument called a gamma-ray spectrometer.

Spectrometers are usually expensive and complex instruments aimed at radiation professionals. But it doesn’t have to be that way: physics enthusiast [NuclearPhoenix] has designed a hand-held gamma spectrometer that’s easy to assemble and should fit in a hobbyist budget. It outputs spectral plots that you can compare with reference data to identify specific elements.

A PCB with a sensor wrapped in black tape — The scintillator and sensor are wrapped in black tape to block out ambient light.

The heart of the device is a scintillation crystal such as thallium-doped sodium iodide which converts incoming gamma rays into visible light. The resulting flashes are detected by a silicon photomultiplier whose output is amplified and processed before being digitized by a Raspberry Pi Pico’s ADC. The Pico calculates the pulses’ spectrum and generates a plot that can be stored on its on-board flash or downloaded to a computer.

[NuclearPhoenix] wrote a convenient program to help analyze the output data and made all design files open-source. The hardest part to find will be the scintillation crystal, but they do pop up on auction sites like eBay now and then. We’ve featured an Arduino-based gamma spectrometer before; if you’ve always wanted to roll your own scintillators, you can do that too. Continue reading “Identify Radioactive Samples With This DIY Gamma-Ray Spectrometer” →

Sensor Playground Keeps Track Of Indoor Air Quality Through The Cloud

March 19, 2022 by Robin Kearey 8 Comments

When [tdw] wasn’t feeling well one day, his wife suggested that it might be due to poor air quality in their home. While an ordinary person could have simply opened a window after hearing such an idea, [tdw] instead showed his true hacker spirit and set about measuring the indoor air quality. He began by designing a simple PCB to measure CO2 and volatile organic compound (VOC) levels, but eventually broadened his scope to end up with the Sensor Playground: a plug-and-play platform to read out various sensors and store the results in the cloud.

Deliberately designed to be easy to assemble with minimal soldering skills, the Sensor Playground consists of a big two-layer PCB onto which various modules can be plugged. It supports either an ESP32 DevKit or an Adafruit Feather module to provide processing power, and provides sockets for a bunch of sensors, conveniently wired with power and SPI or I2C. It also provides a rotary encoder and two buttons for user input. All source files are available on [tdw]’s GitHub page, ready to be applied to any kind of sensing task.

[tdw] set up his Sensor Playground with sensors measuring CO2, VOC, PM2.5 (particulate matter), as well as temperature and relative humidity. A web interface allows anyone to track these measurements in real-time. The open and modular design should make it easy to extend this system with various other sensor types: we can imagine that things like solar irradiation, outside temperature and wind speed would also add useful data to the mix. Perhaps even a Geiger counter to keep track of radiation levels?

As indoor air quality sensors go, this one is definitely comprehensive and easy to use. We’ve featured other air quality sensors before, some of which also link their data to the cloud.

Is Your Tape Dispenser Radioactive?

March 11, 2022 by Al Williams 26 Comments

Do you have anything radioactive in your house? Most people will say no, but they are probably wrong. A host of things ranging from glow-in-the dark timepieces to smoke detectors have some amount of radioactivity. But as [Wheeler Scientific] points out, so do some old Scotch tape dispensers. You can watch the video, below.

The dispenser in question is the C-15 which was very common around offices, military bases, and homes for years. They were made up until the 1980s. You have to wonder why a tape dispenser would be radioactive, and [Wheeler] has the explanation.

When you pull tape from the dispenser, you don’t want the dispenser to slide around the desk, so it needs to be heavy. But no one wants to have a giant dispenser nor do you want to pay for one made from a dense metal. So the plastic dispenser contains a ballast to make it heavier. In the case of the C-15 that ballast is thorium-containing monazite sand. A vintage counter shows the radioactivity which isn’t much, of course, but still way less than the ordinary sand used in newer models. You can also see in the video that the material is paramagnetic.

Monazite used to be a primary source of lanthanides but getting rid of the thorium led to alternate sources in the 1960s although it is still used as an ore for thorium. We know some lenses are radioactive. If you want to search your home for radioactivity and you don’t have a Geiger counter, you don’t need much to build one.

Continue reading “Is Your Tape Dispenser Radioactive?” →

Detecting Alpha Particles Using Copper Wire And High Voltage

January 22, 2022 by Robin Kearey 14 Comments

If you want to measure radioactivity, nothing really beats a Geiger counter: compact, rugged, and reasonably easy to use, they’re by far the most commonly used tool to detect ionizing radiation. However, several other methods have been used in the past, and while they may not be very practical today, recreating them can make for an interesting experiment.

[Mirko Pavleski] used easily obtainable components to build one such device known as an alpha radiation spark detector. Invented in 1945, a spark detector contains a strong electric field into which discharges are triggered by ionizing radiation. Unlike a Geiger-Müller tube, it uses regular air, which makes it sensitive only to alpha radiation; beta and gamma rays don’t cause enough ionization at ambient pressure. Fortunately, alpha radiation is the main type emitted by the americium tablets found in old smoke detectors, so a usable source shouldn’t be too hard to find.

The construction of this device is very simple: a few thin copper wires are suspended above a round metal can, while a cheap high-voltage source provides a strong electric field between them. Sparks fly from the wires to the can when an alpha source is brought nearby; a series resistor limits the current to ensure the wires don’t overheat and melt.

Although not really practical as a measurement device, the spark detector can nevertheless be used to perform simple experiments with radioactivity. As an example, [Mirko] demonstrates in the video embedded below that alpha particles are stopped by a piece of paper and therefore present no immediate danger to humans. The high voltage present in the device does however, so care must be taken with the detector more than with the radiation source.

We’ve seen several homebrew Geiger counters, some built with plenty of duct tape or with the good old 555 timer. But you can also use photodiodes or even certain types of plastic to visualize ionizing radiation.

Continue reading “Detecting Alpha Particles Using Copper Wire And High Voltage” →

Dice Rolls From The Beginning Of Time

January 5, 2022 by Bryan Cockfield 30 Comments

Generating random numbers might seem like a trivial task, that is until the numbers need to be truly random for cryptography or security reasons. When that’s the case, it turns out that these numbers are really “pseudo-random” and follow a predictable pattern. Devices that can produce truly random numbers often do it by sampling random events in the real world rather than relying on a computer to do it directly, like this machine which simulates a dice roll by looking at the cosmic microwave background radiation.

The cosmic microwave background radiation exists in the infrared at the farthest edges of the observable universe as a remnant of the big bang. It’s an excellent source of randomness, but tapping into it poses a bit of a challenge. For this build, [iSax] is using an old Soviet-era Geiger tube to detect the appropriate signal, and a Nixie tube to display the dice roll. After the device detects two particles from the Big Bang, the device measures the amount of time that passed between the detection of both particles and uses this number to calculate the dice roll.

While it takes a little bit longer to roll this dice than a traditional one since it has to wait to detect the right kind of particles, if you really need the randomness it can’t be beat. It certainly works as dice, but we can also see some use for generating truly random numbers for other applications as well. For some other sources of random inspiration be sure to check out our own [Voja Antonic]’s deep dive into truly random number generation.

Continue reading “Dice Rolls From The Beginning Of Time” →

Musical Cyberdeck Is Part Synth, Part MIDI Controller, And All Cool

September 9, 2021 by Dan Maloney 3 Comments

When a new project type starts to get a lot of exposure, it’s typically not long before we see people forking the basic concept and striking out in a new direction. It happened with POV displays, it happened with Nixie clocks, and now, it seems to be happening with cyberdecks. And that’s something we can get behind, especially with cyberdecks built to suit a specialized task, like this musical cyberdeck/synth.

Like many musicians, [Benjamin Caccia] felt like he needed a tool to help while performing with his band “Big Time Kill.” He mainly needed to trigger track playbacks on the fly, but also wanted something to act as a mega-effects pedal and standalone synth. And while most of that could be done with an iPad, it wouldn’t look as cool as a cyberdeck. The build centers around a Raspberry Pi 4 and a 7″ LCD display. Those sit on top of a 25-key USB MIDI keyboard and a small mixer. Alongside the keyboard is a USB keypad, which has custom mappings to allow fast access to buried menu functions in the cyberdeck’s Patchbox OS. Everythign was tied together on a 3D-printed frame; the video below shows it in action, and that it sounds as good as it looks.

We think [Benjamin]’s cyberdeck came out great. Need to see some other specialized cyberdecks? Why not take a look at this battle-ready cyberdeck, one that aims to be distraction-free, or a cyberdeck for patrolling the radioactive wastelands.

Continue reading “Musical Cyberdeck Is Part Synth, Part MIDI Controller, And All Cool” →

a very slapdash x-ray machine on a table

Building An X-Ray Machine

September 9, 2021 by Matthew Carlson 57 Comments

While we typically encourage hackers to make their own tools or machines when practical, x-ray machines don’t usually make that list. Despite the risk of radiation, [William Osman] has done just that and built a homemade x-ray machine. After receiving an eye-watering medical bill, [William] resolves to make his own x-ray machine in the hopes of avoiding future bills. Thanks to his insurance, the total owed was smaller but still ridiculous to those who live in single-payer health care countries, but it got William thinking. What if he could make an x-ray machine to do cheap x-rays?

Armed with a cheap high voltage DC power supply he acquired from an online auction house, he started to power up his x-ray vacuum tube. A smaller power supply energizes the cathode and forms an electron beam. Then the high voltage (30-150kv) is applied as a tube voltage, accelerating the electrons into x-rays. Safety measures are taken somewhat haphazardly with Geiger counters and lead sheets. With a finger bone cast in ballistic shell [William] made his first x-ray with a long exposure on a DSLR. The next items to go in the x-ray “chamber” were a phone and a hand. The results were actually pretty decent and you can clearly see the bones.

We’ve seen homemade X-Ray machines here at Hackaday before, but not one that is constructed perhaps so haphazardly — his approach makes this obvious: don’t try this at home. Video after the break.

Continue reading “Building An X-Ray Machine” →