Sputnik’s Transmitter Beeps Again

February 23, 2016 by 36 Comments

Sputnik. The first artificial satellite, the launch of which precipitated the space race. Without the frenetic pace of technological advancement as the USA and the USSR vied with each other during the decade following its launch it is safe to say that we might not yet have many of the tools and components we take for granted as electronics enthusiasts and makers today.

[Frank Waarsenburg PA3CNO] has taken on the interesting task of recreating one of the Sputnik radio transmitters using a set of the original Russian tubes.

Sputnik itself was an astounding achievement for the team of engineers and scientists who put it into orbit, but the drive to beat the USA to the post within the 1957 International Geophysical Year meant that it was a surprisingly simple device. A sphere pressurised with nitrogen and with those iconic whip antennas mounted on its outside, containing a battery, 20 and 40 MHz tube radio transmitters, and a fan cooling system. Its design was a Soviet state secret, but in 2013 [Oleg, RV3GM] located the schematic used for the transmitter.

The tubes are slightly unusual, being a wire-ended design with all electrodes mounted on rods the length of the glass envelope. This design feature gave them a resistance to acceleration and vibration, making them suitable for use in aircraft, missiles, and rockets.

[Frank] faced one or two hurdles during his construction, including the development of a suitable power supply and finding an unfortunate bug in the Russian schematic. If you speak Dutch or are prepared to use a translation tool his full write-up can be found in the Dutch-language RAZzies magazine, December issue featuring the power supply (PDF, Dutch), and January issue featuring the transmitter (PDF, Dutch).

The Sputnik satellite has not appeared on its own in these pages before, but we have recently featured the early OSCAR amateur radio satellites and the revival of a piece of space-race-era Soviet rocket technology.

Via [Stefan, HB9TWS], whose English-language coverage of the transmitter was of great help.

Worlds Collide: Hot Rodders And Hackers

February 23, 2016 by 59 Comments

When we think of the average hot rodder, we think of guys and gals that love anything on four wheels. They’re good with hand tools, fabrication and know the ins and outs of the internal combustion engine. Their tools of the trade are welders, grinders and boxed-end wrenches. But their knowledge of electric circuits doesn’t go beyond wiring up a 12 volt DC tail light. On the surface, the role of a hot rodder would seem quite different from that of a hardware hacker. But if you abstract what they do, you find that they take machines and modify their design to make them do something more than they were originally designed to do. When viewed in this light, hot rodders are hackers.
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Turn Your Laser Cutter Into An SLS 3D Printer

February 23, 2016 by 18 Comments

Filament style 3D printers are great, but typically are rather size limited. Laser sintering printers offer huge print beds, but also come with quarter million dollar price tags. What are we supposed to do? Well, thanks to OpenSLS, it might just be possible to turn your laser cutter into your very own SLS 3D printer.

We’ve covered OpenSLS a few times before, but it looks like it’s finally becoming a more polished (and usable) solution. A research article was just recently published on the Open-Source Selective Laser Sintering (OpenSLS0 of Nylon and Biocompatible Polycaprolactone (PDF) that goes over the design and construction of a powder handling module that drops right into a laser cutter.

The team has created the hardware to turn a laser cutter with a bed size of 60cm x 90cm into an SLS printer. The beauty? The majority of the hardware is laser cut which means you already have the means to convert your laser cutter into a 3D printer.

The design files are available on their GitHub. Hardware will likely cost you around $2000, which is peanuts compared to the commercial laser sintering printers. There is tons of info in their article — too much for us to cover in a single post. If you end up building one, please let us know!

555 Teardown And Analysis

February 23, 2016 by 9 Comments

If you are even remotely interested in electronics, chances are the number ‘555’ is immediately recognizable. It is, after all, one of the most popular IC’s ever built, with billions of units sold to date. Designed way back in 1970 by Hans Camenzind, it is still widely available and frequently used for various applications. [Ken Shirriff] does a teardown and analysis of a 555 and gives us a look at the internal structure of this oldie.

A metal can package allowed him to just chop off the top and get access to the die, which was way safer and easier than to etch out the black epoxy of a DIP package. He starts by giving us a quick run down on how the chip works, showing us the two comparators, the output flip-flop and the capacitor discharge circuitry that make up most of the chip. He then puts the die under a metallurgical microscope, and starts identifying the various sections of the chip. Combining pictures of individual elements with cross-sectional diagrams, he identifies the construction of the transistors and resistors, the use of a current mirror to replace bulky resistors, and the differential pair that makes up the comparators.

He wraps it up by providing an interactive map of the die and the schematic, where you can click on various parts and the corresponding component is highlighted along with an explanation of what it does. There’s some interesting trivia about how a redesigned, improved version – the ZSCT1555 – couldn’t survive the popularity and success of the 555. He wraps it up with a useful list of notes and references. While de-capping blog posts are interesting on their own, [Ken] does a great job by giving us a detailed look at the internals.

Thanks [Vikas] for sending in this tip.

Lego Nuclear Reactor Uses Arduino

February 22, 2016 by 46 Comments

Before the NSA deletes this post, we’ll be clear: We’re talking about a model of a nuclear reactor, not the real thing. Using Legos, [wgurecky] built a point kinetic reactor model that interfaces with the reactor simulator, pyReactor.

Even without the Lego, the Python code demonstrates reactor control in several modes. In power control mode, the user sets a power output, and the reactor attempts to maintain it. In control rod mode, the user can adjust the position of the control rods and see the results.

If things get out of hand, there’s a SCRAM button to shut the reactor down in a hurry. The Lego model uses an Arduino to move the rods up and down (using a servo) and controls the simulated Cherenkov radiation (courtesy of blue LEDs).

We’ve been excited to see more high schools with significant engineering programs. This would be a good project for kids interested in nuclear engineering. It certainly is a lot safer than one of our previous reactor projects.

Ski Buddy Jacket Uses Arduino To Teach Youngsters To Ski

February 22, 2016 by 2 Comments

Snow skiing looks easy, right? You just stay standing, and gravity does the work. The reality is that skiing is difficult for beginners to learn. [19mkarpawich] loves to ski, but he was frustrated seeing crying kids on skis along with screaming parents trying to coach them. Inspired by wearable electronics, he took an Arduino, an old jacket, some LEDs, and created Ski Buddy.

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Rethinking Automated Bed Leveling For 3D Printers

February 22, 2016 by 38 Comments

Automatic bed leveling is the next killer feature that will be found on all commercial filament printers. It’s a problem that has been solved a few dozen times already; there are just so many ways you can go about it. The Printrbot uses an inductive sensor to determine the position of the metal bed in relation to the nozzle. The Lulzbot Mini touches the nozzle itself to four contacts on the corner of the bed. There are even a few projects that will mechanically level the bed with the help of a system of cams and springs. It’s a difficult problem, and none of these solutions are perfect. [mjrice] has been thinking about the problem, and he hit upon a solution that is simple, elegant, and can be replicated on a 3D printer. It’s the RepRap solution to 3D printing, and it looks cool, to boot.

Instead of using the nozzle as a contact, getting an inductive sensor, or fabricating a baroque system of gears and cams, [mjrice] is doing this the old-fashioned way: a simple microswitch, the same type of switch you would find on the limit switches of any RepRap. Having a switch at the same Z position as a nozzle is an iffy idea, so [mjrice] made this switch retract into the extruder during printing, without using any motors, servos, or other electromechanical contrivances.

The key to this setup is a simple spring and a rack gear. When this rack gear is hit from the left side, it moves an arm and places the switch down on the bed. Hit the rack from the right side, and the switch folds up into the extruder. Combine this with a bit of G-code at the beginning of the print, and the switch will move down, figure out the actual height of the bed, and flip up out of the way. Beautiful, elegant, and the algorithms for bed leveling are already in most major printer firmwares.

You can check out the video of the mechanism below. It’s a great little device, and since it’s on a RepRap first, it’s not going to show up in a proprietary 3D printer next.

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