Retrotechtacular: New York City’s Secret Computer

October 17, 2015 by 78 Comments

Over 750,000 people pass through New York City’s Grand Central Terminal each day. Located in the heart of the city, it’s one of the largest train stations in the world. Its historic significance dates back to 1913, when it opened its doors to the public. At the time, few were aware of the secret computer that sat deep in a sub basement below the hustle and bustle of the city’s busy travelers. Its existence was kept secret all the way into the 1980’s.

Westinghouse had designed a system that would allow authorities to locate a stuck train in a tunnel. There were cords stretched the length of the tunnels. If a train stalled, the operator could reach out and yank on the cord. This would set off an alarm that would alert everyone of the stuck train. The problem being that even though they knew a train was down, they did not know exactly where. And that’s where the computer come in. Westinghouse designed it to calculate where the train was, and write its location on some ticker tape.

So this is the part of the post where we tell you how the computer established where exactly the train breakdown occurred. Although the storyteller in the video is admirably enthusiastic about telling the story, our depth of detail on the engineering that went into this seems nowhere to be found. Let us know in the comments below if you have a source of more information. Or just post your own conjecture on how you would have done it with the early 20th century tech.

The invention of the two way radio made the whole thing obsolete not long after is was built. Never-the-less, it remains intact to this day.

Thanks to [Greg] for the tip!

Powered Skateboards Are Passe; Skelecs The New Hotness

October 17, 2015 by 25 Comments

[Harris] has an interesting answer to the inevitable question about what he did on his summer vacation: he built a pair of electric roller blades.  [Harris] is an Electrical Engineering student at the University of Nottingham, and he completed the first version of what he calls Skelecs just before he went back to college. He has documented the process from the initial concept and building his own controller board, through his failures at correctly drilling the steel base, to his first drive down the road.

His build uses a pair of small 120W hub motors attached to a steel chassis, which is attached to a pair of cannibalized rollerblade boots.

It’s a bit of a Frankenstein build (he currently has the batteries and controller stuffed into a pants pocket, which isn’t really a practical long-term solution), but it works. A bit too well, in fact: [Harris] says that a combination of speed and a bumpy road detached one of the batteries and sent him flying. He’s not letting a minor injury and a bit of blood put him off, though: he’s already started work on version 2, which will use lighter aluminum construction and a pair of omniwheels for easier steering and more control. We’ll believe that claim when we see it.

Remember, powered skateboards are over — non hackers got their hands on them so they’re commonplace. Hipster hackers need to drop that build and start on your own pair of Skelecs.

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Converting A 3D Printer From 3mm To 1.75mm

October 17, 2015 by 12 Comments

A few weeks ago, I published a post discussing the filament diameters common in 3d printing. For no reason whatsoever, consumer 3D printers have settled on two different sizes of filament. Yes, there are differences, but those differences are just a function of engineering tradeoffs and historical choices. [Thomas], YouTube’s 3D printing guru, took this post as a challenge: what does it take to convert a printer to accept different sizes of filament? Not much, actually.

The printer [Thomas] is changing out to accept 1.75mm is the Lulzbot Mini, one of the most popular printers that would ever need this modification. The only required materials is a new hot end suitable for 1.75mm filament, a 4mm drill, and a few wrenches and allen keys. It would be a smart idea to get a hot end that uses the same thermistor as the old one, but that’s not a deal-breaker as the problem can be fixed in the firmware.

Disassembly was easy enough, and after mounting the PTFE tubing, cutting the old wires, soldering in the new hot end, thermistor, and fan, [Thomas] had everything set up and ready to go.

It should be noted that changing a 3mm hot end to 1.75mm doesn’t really do anything. Just about every filament is available in both sizes, although it may not be convenient to buy 3mm filament locally. It would be a good idea to change out the hot end so can standardize your workshop or hackerspace on a single diameter of filament.

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Itsy Bitsy Teenie Weenie 3D Printed RC Truck

October 17, 2015 by 26 Comments

I think it’s safe to say that almost all of us grew up playing with toy cars. They were cheap, and darn near  indestructible. Some went by the brand name of “Hot Wheels”, and others “Matchbox”. As a kid, you most likely spent many an hour on the floor imagining your “toy” to be a real car – and of course, adding the all important sound effects. Vroom-vroommmmm!

Flash forward to 2015, and see how things have changed. There are several “micro” RC cars and trucks on the market you can buy for about $10, but this is the first micro-sized, DIY, 3D printed, 4×4 truck we’ve seen. And to add to that, it even has a working articulated front end loader.

Coming in at a minute 1/87th scale, this tiny truck and matching controller boasts 6 channels, 4-wheel drive, and a working trailer hitch. In the video after the break, you can see the amazing amount of work that [Mortimer] had to put into this build to get everything to fit in such a small space. Although the video is German, we think it’s fairly easy to see what’s going on. [Mortimer] is sharing the 3D printed files on his Shapeways page if you would like to give this build a go.

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You Might Want To Buy A Quadcopter Now

October 16, 2015 by 79 Comments

NBC News has reported the US Government may implement regulations in the coming days that would require anyone who buys an unmanned aircraft system to register that device with the US Department of Transportation.

The most simplistic interpretation of this news is that anyone with a DJI Phantom or a model aircraft made out of Dollar Tree foam board would be required to license their toys. This may not be the case; the FAA – an agency of the US DoT – differentiates between unmanned aircraft systems and model aircraft.

This will most likely be the key thing to watch out for in any coming regulation. The FAA defines model aircraft as, “an unmanned aircraft that is capable of sustained flight in the atmosphere; flown within visual line of sight of the person operating the aircraft; and flown for hobby or recreational purposes.” Additionally, the FAA may not make any regulations for model aircraft. While this means planes and quads flown without FPV equipment may be left out of this regulation, anything flown ‘through a camera’ would be subject to regulation.

bio gas generation

Washington DC Electrified With Raw Sewage

October 16, 2015 by 25 Comments

Completely unrelated to the current political climate in the United States, did you know Washington D.C. is partially powered by a sewage plant? No, seriously.

That’s right, just this week the D.C. Water utility company has announced a bioenergy facility that makes use of resident’s waste water into producing methane gas which can than be burned to generate electricity — To the tune of 10 megawatts! The facility is saving the company an estimated $10 million a year in energy bills.

Simply put, the liquid is removed from the sewage water and the solids are refined into a type of fuel. Those solids are heated, mixed, and sterilized into a form that can be easily digested by a certain type of microbe, which then in turn produce methane for burning. For a more detailed explanation, check out the info-graphic from the Washington Post explaining the entire process.

And on a smaller scale, you could do something like this in your very own backyard.

Make A Cheap (And Dangerous) Automated Flamethrower

October 16, 2015 by 22 Comments

Nothing lights up the night like a quick blast from a flamethrower, but there is a reason why you can’t buy them in the Halloween decoration aisle at Target. They are dangerous, for fairly obvious reasons. [Erco] seems to have no particular fear of death, though, and he shows how you can build a simple flamethrower with a small candle, a servo, Arduino and a can of hairspray. Tresemme Extra Strong Hold, in particular, although we don’t think the exact type matters that much. All he did was to mount the candle in front of the hairspray, then mount the servo so the arm presses the spray head down. The candle does the rest, lighting the highly flammable propellant in the hairspray to produce the flamethrower effect. [Erco] is using four of these, which are co-ordinated to fire in time with music.

This one seems a bit risky. Servos have a habit of locking, and there is nothing stopping these from locking in the open position, or sticking there if the Arduino crashes. A relay or other switch that reverts to an off position when the power is removed would have been more suitable here. Secondly, there is no emergency off switch. [Erco] has wired the Arduino up next to the flamethrower itself, so you are going to have to reach in to disconnect it. That is risky enough, but he also tried a 4-way configuration that would have been impossible to disable in the event of a problem (shown in the accompanying images). Thirdly, there is no fire protection between the can of hairspray and the open flame, so if the spray head melts or fails from the heat, it’s game over. Finally (and most importantly), where are the fire extinguishers? We’d like to hear how you’d build this with safety in mind. Let us know in the comments below.

We’re big fans of flames and explosions: we’ve have seen a couple of Survival Research Laboratory shows and were blown away by their destructive pyrotechnics. But, as SRL head Mark Pauline said in a recent talk, “when things blow up at an SRL show, it’s on purpose”.

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