Warwalking For Radiation

September 10, 2019 by 24 Comments

Can’t find a recently updated survey of radioactivity in your neighborhood? Try [Hunter Long]’s DIY scintillation counter warwalking rig. (Video also embedded below.) What looks like a paint can with a BNC cable leading to an unassuming grey box is actually a complete kit for radiation surveying.

Inside the metal paint can is a scintillation counter, which works by attaching something that produces light when struck by ionizing radiation on the end of a photomultiplier tube, to make even the faintest hits “visible”. And the BNC cable leads to a Raspberry Pi, touch screen, GPS, and the high-voltage converters needed to make the photomultiplier do its thing.

The result is a sensitive radiation detector that logs GPS coordinates and counts per second as [Hunter] takes it out for a stroll. Spoilers: he discovers that some local blacktop is a little bit radioactive, and even finds a real “hot spot”. Who knows what else is out there? With a rig like this, making a radiation map of your local environment is a literal walk in the park.

[Hunter] got his inspiration for the paint-can detector from this old build by [David Prutchi], which used a civil-defense Geiger counter as its source of high voltage. If you don’t have a CD Geiger detector lying around, [Alex Lungu]’s entry into the Hackaday Prize builds a scintillation detector from scratch.
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Global Radiation Montoring And Tracking Nuclear Disasters At Home

August 28, 2019 by 10 Comments

Many of us don’t think too much about radiation levels in our area, until a nuclear disaster hits and questions are raised. Radiation monitoring is an important undertaking, both from a public health perspective and as a way to monitor things like weapon development. So why is it done, how is it done, and what role can concerned citizens play in keeping an eye on things?

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Apollo’s PLSS And The Science Of Keeping Humans Alive In Space

August 19, 2019 by 13 Comments

Ever since humans came up with the bright idea to explore parts of the Earth which were significantly less hospitable to human life than the plains of Africa where humankind evolved, there’s been a constant pressure to better protect ourselves against the elements to keep our bodies comfortable. Those first tests of a new frontier required little more than a warm set of clothes. Over the course of millennia, challenging those frontiers became more and more difficult. In the modern age we set our sights on altitude and space, where a warm set of clothes won’t do much to protect you.

With the launch of Sputnik in 1957 and the heating up of the space race between the US and USSR, many firsts had to be accomplished with minimal time for testing and refinement. From developing 1945’s then state-of-the-art V-2 sounding rockets into something capable of launching people to the moon and beyond, to finding out what would be required to keep people alive in Earth orbit and on the Moon. Let’s take a look at what was required to make this technological marvel happen, and develop the Portable Life Support System — an essential component of those space suits that kept astronauts so comfortable they were able to crack jokes while standing on the surface of the Moon.

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A PKE Meter That Actually Detects Radiation

July 24, 2019 by 5 Comments

Fans of Ghostbusters will remember the PKE meter, a winged handheld device capable of detecting supernatural activity. Precious little technical data on the device remains, leaving us unable to replicate its functionality. However, the flashing, spreading wings serve as a strong visual indicator of danger, and [mosivers] decided this would be perfect for a Geiger counter build.

An SBM20 Geiger tube serves as the detection device, hooked up to an Arduino Nano. An OLED display is used to display the numerical data to the user. The enclosure and folding wings are 3D printed, and fitted with 80s-style yellow LEDs as per the original movie prop.

The device is quite intuitive in its use – if the wings flare out and the lights are flashing faster, you’re detecting an increased level of radiation. In a very real sense, it makes using a Geiger counter much more straightforward for the inexperienced or the hearing impaired. Naturally, there’s also a buzzer generating the foreboding clicks as you’d expect, too.

Geiger counters are a popular project, though we hope they don’t become common household items in the near future. Here’s a Fallout-inspired build for fans of the game. Video after the break.

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DIY Scintillation Detector Is Mighty Sensitive

July 19, 2019 by 24 Comments

Geiger counters are a popular hacker project, and may yet prove useful if and when the nuclear apocalypse comes to pass. They’re not the only technology out there for detecting radiation however. Scintillation detectors are an alternative method of getting the job done, and [Alex Lungu] has built one of his own.

Scintillation detectors have several benefits over the more common Geiger-Muller counter. They work by employing crystals which emit light, or scintillate, in the presence of ionizing radiation. This light is then passed to a photomultiplier tube, which emits a cascade of electrons in response. This signal represents the level of radioactivity detected. They can be much more sensitive to small amounts of radiation, and are more sensitive to gamma radiation than Geiger-Muller tubes. However, they’re typically considered harder to use and more expensive to build.

[Alex]’s build uses a 2-inch sodium iodide scintillator, in combination with a cheap photomultiplier tube he scored at a flea market for a song. [Jim Williams]’s High Voltage, Low Noise power supply is used to run the tube, and it’s all wrapped up in a tidy 3D printed enclosure. Output is via BNC connectors on the rear of the device.

Testing shows that the design works, and is significantly more sensitive than [Alex]’s Geiger-Muller counter, as expected. If you’re interested in measuring small amounts of radiation accurately, this could be the build for you. We’ve seen this technology used to do gamma ray spectroscopy too.

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Hacking Shelters And Swimming Pools

July 18, 2019 by 44 Comments

How would you survive in a war-torn country, where bombs could potentially fall from the sky with only very short notice? And what if the bomb in question were The Bomb — a nuclear weapon? This concern is thankfully distant for most of us, but it wasn’t always so. Only 75 years ago, bombs were raining down on England, and until much more recently the threat of global thermonuclear war was encouraging school kids to “duck and cover”. How do you protect people in these situations?

The answers, naturally, depend on the conditions at hand. In Britain before the war, money was scarce and many houses didn’t have basements or yards that were large enough to build a family-sized bomb shelter in, and they had to improvise. In Cold War America, building bomb shelters ended up as a boon for the swimming pool construction industry. In both cases, bomb shelters proved to be a test of engineering ingenuity and DIY gumption, attempting to save lives in the face of difficult-to-quantify danger from above.

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A Lot Of Volts For Not A Lot

July 13, 2019 by 23 Comments

There was a time when high voltage in electronic devices was commonplace, and projects driving some form of vacuum or ionisation tube simply had to make use of a mains transformer from a handy tube radio or similar. In 2019 we don’t often have the need for more than a few volts, so when a Geiger–Müller tube needs a bit of juice, we’re stumped. [David Christensen] approached this problem by creating his own inverter, which can produce up to 1 kV from a 12 V supply.

Instead of opting for a flyback supply he’s taken a traditional step-up approach, winding his own transformer on a ferrite core. It has a centre-tapped primary which he drives in push-pull with a couple of MOSFETS, and on its secondary is a voltage multiplier chain. The MOSFETs take their drive at between 25 kHz and 50 kHz from a 555 timer circuit, and there is no feedback circuit.

It’s fair to say that this is a somewhat hair-raising circuit, particularly as he claims that it is capable of delivering that 1 kV at 20 W. It’s usual for high-voltage supplies driving very high impedance loads to incorporate a set of high-value resistors on their outputs to increase their internal impedance such that their danger is reduced. We’d thus exercise extreme care around this device, though we can see a lot of value in his description of the transformer winding.

We can’t criticise this circuit too much though, because some of us have been known to produce far hackier high voltage PSUs.