uv

82 Articles

Power Line Patrols: The Grid’s Eye In The Sky

July 29, 2025 by 18 Comments

Those of us who like to monitor air traffic with ADS-B aggregators such as FlightAware and ADS-B Exchange tend to see some interesting flight paths. I’m not talking about the truly ambitious pictures drawn by pilots, or even the more ribald ones, but rather flights that follow paths that seem to make little sense from either a commercial or leisure standpoint.

Most of these mystery flights have long straight stretches interrupted by occasional tight loops, and often cover great distances across rural and urban landscapes alike. A glance at the ADS-B data indicates that these flights are usually pretty close to the ground, and are often completed by helicopters. Occasionally, the registration of the aircraft will even indicate ownership by some “three-letter” federal agency.

Although mystery helicopters flying odd patterns in the sky seems like a good excuse to don a tinfoil hat and head to one’s bunker, chances are pretty good that these aircraft are engaged in a far less nefarious and far more useful endeavour: aerial transmission line patrols. These flights are key to keeping the transmission lines that form the backbone of the grid in tip-top shape, especially at a time of unprecedented growth in load and a shift in the generation profile away from fossil fuels towards renewables.

Continue reading “Power Line Patrols: The Grid’s Eye In The Sky” →

Upper Room UV-C Keeps Air Cleaner

December 18, 2024 by 59 Comments

2020 saw the world rocked by widespread turmoil, as a virulent new pathogen started claiming lives around the globe. The COVID-19 pandemic saw a rush on masks, air filtration systems, and hand sanitizer, as terrified populations sought to stave off the deadly virus by any means possible.

Despite the fresh attention given to indoor air quality and airborne disease transmission, there remains one technology that was largely overlooked. It’s the concept of upper-room UV sterilization—a remarkably simple way of tackling biological nastiness in the air.

Continue reading “Upper Room UV-C Keeps Air Cleaner” →

Homebrew Phosphorescence Detector Looks For The Glow In Everyday Objects

November 28, 2024 by 8 Comments

Spoiler alert: almond butter isn’t phosphorescent. But powdered milk is, at least to the limit of detection of this homebrew phosphorescence detector.

Why spend a bunch of time and money on such a thing? The obvious answer is “Why not?”, but more specifically, when [lcamtuf]’s son took a shine (lol) to making phosphorescent compounds, it just seemed natural for dad to tag along in his own way. The basic concept of the detector is to build a light-tight test chamber that can be periodically and briefly flooded with UV light, charging up the putatively phosphorescent compounds within. A high-speed photodiode is then used to detect the afterglow, which can be quantified and displayed.

The analog end of the circuit was the far fussier end of the design, with a high-speed transimpedance amplifier to provide the needed current gain. Another scaling amp and a low-pass filter boosts and cleans up the signal for a 14-bit ADC. [lcamtuf] went to great lengths to make the front end as low-noise as possible, including ferrite beads and short leads to prevent picking up RF interference. The digital side has an AVR microcontroller that talks to the ADC and runs an LCD panel, plus switches the 340 nm LEDs on and off rapidly via a low gate capacitance MOSFET.

Unfortunately, not many things found randomly around the average home are all that phosphorescent. We’re not sure what [lcamtuf] tried other than the aforementioned foodstuffs, but we’d have thought something like table salt would do the trick, at least the iodized stuff. But no matter, the lessons learned along the way were worth the trip.