A Bird 43 wattmeter and its homebrew equivalent

Homebrew Wattmeter Pays Homage To Sturdy Original

September 27, 2021 by Dan Maloney 12 Comments

If there’s one instrument that hams and other radio enthusiasts covet, it’s the venerable Bird 43 Thruline wattmeter. The useful RF tool has barely changed in the nearly 70 years since it was first introduced, and they’re built like a tank. This makes Bird meters highly desirable, and therefore quite expensive either brand new or on the swap-meet circuit.

But radio amateurs are nothing if not resourceful, and building a homebrew version of the Bird wattmeter (in Portuguese; Google translate tool at the bottom of the page) as Brazilian ham [Luciano Sturaro (PY2BBS)] did is a good way to get your hands on one. Granted, [Luciano] had a head start: a spare line set, which is the important bit from a Bird wattmeter. The machined metal part is in effect an air-insulated section of coaxial cable that the RF signal passes through on its way from transmitter to antenna. A “slug” is inserted into the cavity in the line set to sense the RF and couple it to the meter electronics; the slug can be rotated to measure RF traveling in either direction, allowing the user to determine how much RF is getting reflected by the antenna system.

[Luciano]’s version of the meter is faithful to the sturdy construction of the original, with a solid steel case that mimics its classic lines — the case even sports the same color scheme and stout leather carry handle. There are some changes to the electronics, and the meter movement itself is different from the original, but all in all, the “Buzz 50” looks fantastic. We especially love the detailed nameplate as an homage to Bird.

The thing about Bird — and Bird-like — meters is that the slugs are like potato chips; you can’t have just one. Curious as to how these slugs work? Check out this slug repair project.

[Featured image of Bird 43 Wattmeter: Martin RF Supply]

Thanks to [Niko Huenk] for the tip!

But Can Your AI Recognize Slugs?

April 5, 2019 by Dan Maloney 53 Comments

The common garden slug is a mystery. Observing these creatures as they slowly emerge from their slimy lairs each evening, it’s hard to imagine how much damage they can do. With paradoxical speed, they can mow down row after row of tender seedlings, leaving nothing but misery in their mucusy wake.

To combat this slug menace, [Tegwyn☠Twmffat] (the [☠] is silent) is developing this AI-powered slug busting system. The squeamish or those challenged by the ethics of slug eradication can relax: no slugs have been harmed yet. So far [Tegwyn] has concentrated on the detection of slugs, a considerably non-trivial problem since there are few AI models that are already trained for slugs.

So far, [Tegwyn] has acquired 5,712 images of slugs in their natural environment – no mean feat as they only come out at night, they blend into their background, and their slimy surface makes for challenging reflections. The video below shows moderate success of the trained model using a static image of a slug; it also gives a glimpse at the hardware used, which includes an Nvidia Jetson TX2. [Tegwyn] plans to capture even more images to refine the model and boost it up from the 50 to 60% confidence level to something that will allow for the remediation phase of the project, which apparently involves lasers. Although he’s willing to entertain other methods of disposal; perhaps a salt-shooting turret gun?

This isn’t the first garden-tending project [Tegwyn] has tackled. You may recall The Weedinator, his 2018 Hackaday Prize entry. This slug buster is one of his entries for the 2019 Hackaday Prize, which was just announced. We’re looking forward to seeing the onslaught of cool new projects everyone will be coming up with.

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An Electric Fence For Snails And Slugs

June 29, 2017 by Adam Fabio 72 Comments

Anyone with a garden knows about doing battle with pests. Weeds, bugs, rabbits, birds — all of them try to get a bite out of our flowers and vegetables. Some of the worst are mollusks. Snails and slugs are notorious plant attackers. Tomato plants don’t stand a chance when these beasts come to town. Some folks would reach for the pesticide or even the salt, but [wheldot] had a better idea. He built an electric fence to keep these pests at bay.

Much like the electric fences used for large mammals like horses or cows, this fence is designed to deter, but not kill slugs and snails. The design is incredibly simple – two bare wires are strung around the raised garden about one centimeter apart. The wires are connected to a nine-volt battery. No boost circuit, no transistors, just nine volts across two wires. That’s all it takes to turn a slug away.

[Wheldot] didn’t come up with this hack — it’s been around in various forms for years. The nine-volt battery provides just enough current to annoy the slug or snail. The best part is that when not actively shocking a slug, the only current passing through the circuit is the whatever is passed through the wood.

Reddit user [gnichol1986] measured that at around 180 kΩ through wet wood. That means a typical 400 mAh battery would last around 34 days of continuous rain. Even in the UK it doesn’t rain that much. With a little work insulating the wires from the wood, that could be extended to the full shelf life of the battery.

You know, slugs and critters get into electronics too, so don’t forget a waterproof case to make sure your project stays slug free!

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Sluggy Wind Speed Sensor

December 4, 2010 by James Munns 7 Comments

Sometimes when we look at a hack, its to see how someone chose those parts for the project. In this case, it would have been hard to see it coming. [Janne Jansson] decided to combine a set of measuring cups, a hacked Linksys NSLU2 NAS, and a PS/2 Mouse together to make a self-contained Wind Speed Sensor for his roof. The measuring cups act as wind catchers, which in turns drives the rotation of one of the mouse ball sensors. This data is then logged and transmitted by the NSLU2. The NSLU2 is running a custom Linux based firmware, similar to how OpenWRT works for wireless routers.

To calibrate the device, he also made the best logical choice: to duct tape it to the hood of his car along with a much more expensive wind sensor and use that data to make his own device as accurate as possible. When placed atop his house with a 1500VA 220V UPS, the device managed 250 days of uptime before meeting its demise. Those 250 days also included 5 days of being frozen solid, yet still transmitting (somewhat meaningless) data. All of the relevant code and build instructions are available, for those of you with similar parts to spare.

Hackit: Network Attached Storage?

July 5, 2008 by Eliot 24 Comments

With each passing day the rate we acquire digital media increases (we don’t even bother unpacking our CDs when we move anymore). Large publishers have started moving away from DRM, which means we’ll be buying even more digital media in the future. Acquiring all of this nonphysical property puts importance on not just making it easily accessible, but also protecting it from destruction. Slashdot asked for reader suggestions of what NAS to buy; we’ve compiled some of the options below and want to know what you use.