The Strange Physics Of Curling

February 20, 2018 by Adam Fabio 36 Comments

It turns out that curling involves some complex physics. [Destin] of Smarter Every Day has jumped in to find out why scientists on opposite sides of the Atlantic disagree about why curling stones curl.

If you’ve been watching the Olympics, you’ve probably seen some curling, the Scottish sport of competitively pushing stones on ice. As the name implies, curling stones don’t go straight. The thrower pushes them with a bit of rotation, and the stones curve in the direction they are rotating. This is exactly the opposite of what one would expect — try it yourself with an inverted drinking glass on a smooth table. The glass will curl opposite the direction of rotation. Clockwise spin will result in a curl to the left, counterclockwise in a curl to the right.

The cup makes sense when you think about the asymmetrical friction involved. The cup is slowing down, which means more pressure on the leading edge. The rotating leading edge pushes harder against the table and causes the cup to curl opposite the direction of rotation.

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Debunking Moon Landing Denial With An Arduino And Science

February 20, 2018 by Dan Maloney 105 Comments

It’s sad that nearly half a century after the achievements of the Apollo program we’re still arguing with a certain subset of people who insist it never happened. Poring through the historical record looking for evidence that proves the missions couldn’t possibly have occurred has become a sad little cottage industry, and debunking the deniers is a distasteful but necessary ongoing effort.

One particularly desperate denier theory holds that fully spacesuited astronauts could never have exited the tiny hatch of the Lunar Excursion Module (LEM). [AstronomyLive] fought back at this tendentious claim in a clever way — with a DIY LIDAR scanner to measure Apollo artifacts in museums. The hardware is straightforward, with a Garmin LIDAR-Lite V3 scanner mounted on a couple of servos to make a quick pan-tilt head. The rig has a decidedly compliant look to it, with the sensor flopping around a bit as the servos move. But for the purpose, it seems perfectly fine.

[AstronomyLive] took the scanner to two separate museum exhibits, one to scan a LEM hatch and one to scan the suit Gene Cernan, the last man to stand on the Moon so far, wore while training for Apollo 17. With the LEM flying from the rafters, the scanner was somewhat stretching its abilities, so the point clouds he captured were a little on the low-res side. But in the end, a virtual Cernan was able to transition through the virtual LEM hatch, as expected.

Sadly, such evidence will only ever be convincing to those who need no convincing; the willfully ignorant will always find ways to justify their position. So let’s just celebrate the achievements of Apollo.

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Tiny Guitar Amp Rebuilt With Tiny Tubes

February 19, 2018 by Tom Nardi 28 Comments

[Blackcorvo] wrote in to tell us how he took a cheap “retro” guitar amplifier and rebuilt it with sub-miniature vacuum tubes. The end result is a tiny portable amplifier that not only looks the part, but sounds it to. He’s helpfully provided wiring schematics, build images, and even a video of the amplifier doing it’s thing.

The original Honeytone amplifier goes for about $26, and while it certainly looks old-school, the internals are anything but. [Blackcorvo] is too much of a gentleman to provide “before” pictures of the internals, but we looked it up and let’s just say it doesn’t exactly scream high quality audio. Reviews online seem to indicate it works about as well as could be expected for an amplifier that costs less than $30, but this is definitely no audiophile gear.

Powering up the miniature vacuum tubes takes a bit of modern support electronics, including a buck converter to provide the high voltage for the tubes as well as a 6V regulator. The plus side is that the new circuit can power the tubes from an input voltage between 12 and 30 volts, meaning the amplifier can still be powered by batteries if you want to take it on the go.

We’ve seen some fantastic tube amplifier builds over the years, proving that some things never go out of style. If you’d like to learn more about the magic that lets these little tubes of hot pixies make beautiful music, the US Army has you covered.

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Milspec Teardown: CP-142 Range Computer

February 19, 2018 by Tom Nardi 69 Comments

As some of my previous work here at Hackaday will attest to, I’m a big fan of World War II technology. Something about going in with wooden airplanes and leaving with jet fighters and space capable rockets has always captivated me. So when one of my lovingly crafted eBay alerts was triggered by something claiming to be a “Navy WWII Range Computer”, it’s safe to say I was interested.

Not to say I had any idea of what the thing was, mind you. I only knew it looked old and I had to have it. While I eagerly awaited the device to arrive at my doorstep, I tried to do some research on it and came up pretty much empty-handed. As you might imagine, a lot of the technical information for hardware that was developed in the 1940’s hasn’t quite made it to the Internet. Somebody was selling a technical manual that potentially would have covered the function of this device for $100 on another site, but I thought that might be a bit excessive. Besides, where’s the fun in that?

I decided to try to decipher what this device does by a careful examination of the hardware, consultation of what little technical data I could pull up on its individual components, and some modern gear. In the end I think I have a good idea of how it works, but I’d certainly love to hear if there’s anyone out there who might have actually worked with hardware like this and could fill in any blanks.

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Help Keep The Bombe At Bletchley

February 17, 2018 by Jenny List 36 Comments

Fans of vintage codebreaking machinery might be interested to hear that the only working reconstruction of a Turing-Welchman Bombe is likely to soon be on the move. The electromechanical device, a replica of those used on the Second World War Enigma codes, is housed at Bletchley Park, the former codebreaking center established before the outbreak of war to house British and Polish codebreakers.

Bletchley Park itself is now a tourist attraction. The news is that a display reorganization has caused the Turing Welchman Bombe Rebuild Trust that owns the Bombe to approach the neighboring National Museum Of Computing with a view to housing it alongside their reconstruction of the Colossus electronic computer. The Colossus was famously used on the Lorenz cipher. This is an exciting development for the museum, but as an organization reliant on donations they face the task of finding the resources to create a new gallery for the arrival. To that end, they have launched a crowdfunding campaign with a target of £50000 ($69358.50), and they need your donations to it for the project to succeed. They have raised over £4500 in the few days it has already been open and there is most of a month still to go, so we hope they achieve their goal.

The Bletchley Park site is now surrounded by the post-war new town of Milton Keynes, and is easy enough to get to should you find yourself in the UK. We visited The National Museum Of Computing a couple of years ago and spent a very happy day touring its extensive and fascinating collection. If you want to read more about the Bombe you might like to read our review, and also our impression of Colossus.

As part of their campaign, the museum has produced a promotional video, which we have placed after the break.

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This Boxing Bell Is A Trip

February 17, 2018 by Adam Fabio 8 Comments

[MeasuredWorkshop] wanted to know how a boxing bell mechanism worked. The best way to learn is by doing, so he jumped right in and built one! Boxing bells are a rare surviving example of the trip bell mechanism. Trip bells were used in schools and public buildings as fire alarms. They’ve since been replaced by modern electric systems.

The mechanical linkage behind the trip bell is a one-way lever. This is the arm you pull on. It has a hinged section which stays rigid when the arm is pulled down, but rotates away when the arm is released. [Measured Workshop] built the mechanics of his bell using rather basic tools. The brunt of the work was handled by an angle grinder and a drill press.

The sounder for this boxing bell came from an old school bell. The industrial grey paint was chemically stripped, and the metal cleaned up for a nice brushed finish. The metal stands out nicely against the wood board [Measured Workshop] used as a base.

The finished product looks and sounds the part – now he just has to find a boxing gym in need of a bell!

We’re really becoming fond of the “wordless workshop” style videos that have been popping up on YouTube. [Jimmy DiResta] has been doing it for years, and relative newcomers [HandToolRescue] and [Measured Workshop] are both producing some great content!

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Resurrecting An Amiga CD32

February 16, 2018 by Richard Baguley 15 Comments

As an editor on Amiga magazines in a previous life, this is kind of bittersweet. [RetroManCave] was donated an Amiga CD32 games system, and it is trying to resurrect it. If you’ve not heard of it, the CD32 was a 1993 games console based on the Amiga home computer system. It was the last gasp for Commodore, the beleaguered company behind the Amiga. In this first video of a series, they take the system apart, take you through what’s inside and boot it up. The system boots, but there is some sort of problem with the video sync, and they will be taking a closer look at fixing that next. We have featured a couple of similar projects from [RetroManCave] before, such as their brain transplant on a Big Trak toy and Commodore 64 fix. This video (after the break) is worth a watch if you are curious about old systems like this, want some tips on resurrecting old hardware or just want to shed a tear as your misspent youth is torn apart before your eyes.

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