Hacking Apollo Hack Chat

April 20, 2020 by Dan Maloney 2 Comments

Join us on Wednesday, April 22 at noon Pacific for the Hacking Apollo Hack Chat with “CuriousMarc” Verdiell, Ken Shirriff, Mike Stewart, and Carl Claunch!

When President Kennedy laid down the gauntlet to a generation of scientists and engineers to land a man on the Moon before the close of the 1960s, he likely had little idea what he was putting in motion. The mission was dauntingly complex, the science was untested, and the engineering was largely untried. Almost everything had to be built from scratch, and entire industries were born just from the technologies that had to be invented to make the dream come true.

Chief among these new fields was computer science, which was barely in its infancy when the 1960s started. By the end of the decade and the close of the Space Race, computers had gone from room-filling, power-guzzling machines to something compact and capable enough to fly men to the Moon and back. The computers that followed all built on the innovations that came about as a result of Apollo, and investigating the computers of the era and finding out what made them tick is an important part of our technological culture.

That’s where this retrocomputing dream team came into play. Together, they’ve poked and prodded at every bit of hardware from the Space Race era they could find, including a genuine Apollo Guidance Computer (AGC) that was rescued from the trash. What’s more, they actually managed to restore it to working condition with a series of epic hacks and sheer force of will.

Marc, Ken, Mike, and Carl will stop by the Hack Chat to talk about everything that went into getting the AGC working again, along with anything else that pops up. Come ready to have your Apollo-era hardware itches scratched by the people who’ve been inside a lot of it, and who have seen first-hand what it took to make it to the Moon and back.

Our Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, April 22 at 12:00 PM Pacific time. If time zones have got you down, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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Measuring Sharpie Thickness… The Ink Itself, Not The Pen!

April 20, 2020 by Mike Szczys 29 Comments

How we missed this one from a few years ago is unknown, but we’re glad to catch up with it now. Have you ever needed to measure how thick the ink in a Sharpie line is? Of course you haven’t. But if you needed to, how would you do it? Using a wicked-sensitive indicator gauge and levering an interesting test setup.

[Tom] from [oxtoolco] got his hands on a tool that measures in 1/10,000,000th (that’s one ten-millionth) increments and was wondering what kind of shenanigans you can do with this Lamborghini of dial indicators. It’s one thing to say you’re going to measure ink, but coming up with the method is the leap. In this case it’s a gauge block — a piece of precision ground metal with precise dimensions and perfectly perpendicular faces. By zeroing the indicator on the block, then adding lines from the Sharpie and measuring again, you can deduce the thickness of the ink markings.

After arraying diagonal lines on the gauge block it is placed lines-down under the dial indicator. This distributes the ink layer across a larger area, as probing the ink line directly would likely result in inaccurate readings. On that topic the gauge block is moved using pliers, as introducing heat from your fingers could result in expansion of the metal upsetting the readings.

The results? Black, blue, and red Sharpie were all tested, alongside blue and black Dykem layout fluid. Ten samples of each were run and the readings were all very close, save a couple of obvious outliers. Clocking in the thinnest is black Sharpie at about 118 millionths of an inch (~30 microns) and blue Dykem was the thickest at 314 millionths (86 microns). [Tom] quips that since we now know the thickness, you could even use ink as a shim.

If you can’t get enough Sharpie in your life, try it as an extremely satisfying add-on for your plasma cutter.

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Inputs Of Interest: The Differently Dexterous DataHand Directionalizes Digits

April 20, 2020 by Kristina Panos 24 Comments

If you had debilitating pain from repetitive stress injury in the 1990s, there were a lot of alternative keyboard options out there. One of the more eye-catching offerings was the DataHand keyboard made by DataHand Systems out of Phoenix, AZ. The DataHand debuted in 1993 with a price tag around $2,000. While this is admittedly pretty steep for the average consumer, it was well within the IT budgets of companies that wanted to avoid workman’s comp claims and keep their employees typing away.

In theory, this is holy grail territory for anti-RSI keyboards. The DataHand was designed to eliminate wrist motion altogether by essentially assigning a d-pad plus a regular push-down button to each finger. The layout resembles QWERTY as closely as possible and uses layers to access numbers, symbols, and other functions, like a rudimentary mouse.

Although if you put them this close together, you’re kind of missing the point. Image via Bill Buxton

Ergonomic to the Max

Typing on the DataHand is supposed to be next to effortless. The directional switches are all optical, which probably has a lot to do with the eye-popping price point. But instead of being spring-loaded, these switches use magnets to return to the neutral position.

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Test Unknown Fuses Without Destroying Them

April 20, 2020 by Dan Maloney 31 Comments

There’s a problem with fuses. On the face of it, testing would seem to be a one-shot deal — exceed the rated current and see if it blows. But once you know the answer, the device is useless. If only there were a way to test fuses without damaging them.

As it turns out there is, and [Kerry Wong] weaves quite a tale about his attempts to non-destructively test fuses. The fuses in question are nothing fancy — just the standard glass tube type, from a cheap assortment kit off Amazon. Therein lies the problem: can such cheap devices be trusted? Finding out requires diving much deeper into the technology of fuses than many people will have done, including understanding how the thermal and electrical characteristics of the fuse element behave.

[Kerry]’s test setup is simple, consisting of a constant current power supply and a voltmeter across the fuse to measure the voltage drop caused by the resistance of the fuse element. As he ramps up the current, the voltage drop increases linearly due to the increase in resistance of the alloy with increasing temperature. That only lasts up to a point, where the fuse resistance starts increasing exponentially. Pushing much past the point where the resistance has doubled would blow the fuse, so that’s the endpoint of his tests. Perhaps unsurprisingly, his no-name fuses all went significantly beyond their rated current, proving that you get what you pay for. See the video below for the tests and an analysis of the results.

It’s handy to know there’s a way to check fuses without popping them, and we’ll file this one away for future reference. Don’t forget that you should always check the fuse when troubleshooting, because you never know what the last person did to it.

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Roll Your Own Automation With ESPHome

April 20, 2020 by Donald Papp 17 Comments

There are several different paths to a smart home, and [Marcus] eventually settled on using ESPHome and ESP8266/ESP32 based devices to create a complete DIY smart home solution which covers his garage door, sprinklers, LED strips, light bulbs, and outlets. There’s even an experimental (and very economical) ESP32-CAM based camera, shown here.

In fact, [Marcus]’s write-up could double as a sort of reference design. If you’re curious about ESPHome, be sure to read what he has to say because he explains exactly how he configured each device and any challenges he encountered in the process.

Beyond the software guidance, the post is also a great resource on how to flash a new firmware onto several different smart devices. [Marcus] provides nicely labeled images of the boards that show where you need to connect your programmer, which just might save you some trouble down the line. Though he did manage to set fire to one of the bulbs, so keep an eye out for that.

Tasmota is another open source option for controlling ESP8266-based devices, and if you’d like to explore that direction don’t forget that flashing Sonoff devices with Tasmota firmware recently got much, much easier.

Magnetic Bubble Memory Farewell Tour

April 19, 2020 by Al Williams 13 Comments

There’s something both satisfying and sad about seeing an aging performer who used to pack a full house now playing at a local bar or casino. That’s kind of how we felt looking at [Craig’s] modern-day bubble memory build. We totally get, however, the desire to finish off that project you thought would be cool four decades ago and [Craig] seems to be well on the way to doing just that.

If you don’t recall, bubble memory was going to totally wipe out the hard drive industry back in the late 1970s and early 1980s. A byproduct of research on twistor memory, the technology relied on tiny magnetic domains or bubbles circulating on a thin film. Bits circulated to the edge of the film where they were read using a magnetic pickup. Then a write head put them back at the other edge to continue their journey. It was very much like the old delay line memories, but with tiny magnetic domains instead of pressure waves through mercury.

We don’t know where [Craig] got his Intel 7110 but they are very pricey nowadays thanks to their rarity. In some cases, it’s cheaper to buy some equipment that used bubble memory and steal the devices from the board. You can tell that [Craig] was very careful working his way to testing the full board.

Because these were state-of-the-art in their day, the chips have extra loops and would map out the bad loops. Since the bubble memory is nonvolatile, that should be a one time setup at the factory. However, in case you lost the map, the same information appears on the chip’s label. [Craig’s] first test was to read the map and compare it to the chip’s printed label. They matched, so that’s a great sign the chip is in good working order and the circuit is able to read, at least.

We’ve talked about bubble memory before along with many other defunct forms of storage. There were a few military applications that took advantage of the non-mechanical nature of the device and that’s why the Navy’s NEETS program has a section about them.

Gain An Understanding Of Injection Molding’s Design Gotchas

April 19, 2020 by Donald Papp 11 Comments

When it comes to manufacturing, sheet metal and injection molding make the world go ’round. As a manufacturing method, injection molding has its own range of unique design issues and gotchas that are better to be aware of than not. To help with this awareness, [studiored] has a series of blog posts describing injection molding design issues, presented from the perspective of how to avoid and address them.

Design of screw bosses demonstrating conflict between molder’s guidelines and vendor’s recommendations. Compromising between both is a science and an art.

Because injection molding involves heat, warp is one issue to be aware of and its principles will probably be familiar to anyone with nitty-gritty experience in 3D printing. Sink marks are also an issue that comes down to differential cooling causing problems, and can ruin a smooth and glossy finish. Both of these play a role in how best to design bosses.

Minimizing and simplifying undercuts (similar to overhangs in 3D printer parlance) is a bit more in-depth, because even a single undercut means much more complex tooling for the mold. Finally, because injection molding depends on reliably molding, cooling, and ejecting parts, designing parts with draft (a slight angle to aid part removal) can be a fact of life.

[studiored] seems to have been working overtime on sharing tips for product design and manufacture on their blog, so it’s worth keeping an eye on it for more additions. We mentioned earlier that much of the manufacturing world revolves around injection molding and sheet metal, so to round out your knowledge we published a primer on everything you need to know about the art and science of bending sheet metal. With a working knowledge of the kinds of design issues that affect these two common manufacturing methods, you’ll have a solid foundation for any forays into either world.