Gentle Introduction To White Light Interferometry

March 13, 2024 by Maya Posch 3 Comments

Screenshot of the Zygo white light interferometry microscope software. (Credit: Huygens Optics)

White light interferometry (WLI) is a contact-free optical method for measuring surface height. It uses the phase difference between the light reflected off a reference mirror and the target sample to calculate the height profile of the sample’s surface. As complex as this sounds, it doesn’t take expensive hardware to build a WLI microscope, as [Huygen Optics] explains in a detailed introductory video on the topic. At its core you need a source of white light (e.g. a white LED), with a way to focus the light so as to get a spatially coherent light source, like aluminium foil with a pin hole and a lens.

This light source then targets a beam splitter, which splits the light into one beam that targets the sample, and one that targets the reference mirror. When both beams are reflected and return to the beam splitter, part of the reflected light from either side ends up at the camera, which captures the result of the reference and sample beams after their interference (i.e. combination of the amplitudes). This creates a Michelson interferometer, which is simple, but quite low resolution. For the demonstrated Zygo Newview 100 WLI microscope this is the first objective used, followed by a more recent innovation: the Mirau interferometer, which integrates the reference mirror in such a manner that much higher resolutions are possible, down to a few µm.

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FLOSS Weekly Episode 774: Let’s Get Rusty

March 13, 2024 by Jonathan Bennett 5 Comments

This week, Jonathan Bennett chats with Herbert Wolverson about Rust! Is it really worth the hype? Should you have written that in Rust? What’s up with “if let some” anyways? And what’s the best way to get started with this exciting language? We also cover comparisons with other languages like Ada, what drives us crazy about Cargo, and the fascinating world of kernel development!

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Goldilocks Beverage Coaster Tells You When It’s Just Right

March 13, 2024 by Kristina Panos 17 Comments

If you ask us, morning is the only excuse we need for a hot caffeinated beverage — weather be damned. Wherever [gokux] is, they may be experiencing actual winter this year, given that they are out there getting cozy with a hot cup of what-have-you. But how do they know it’s at the right temperature for drinking? Enter the temperature-monitoring smart coaster.

At the heart of this build is a GY-906 infrared temperature sensor, which senses the warmth (or lack thereof) and displays the degrees on a small OLED screen thanks to a Seeed Xiao SAMD21. To make things simple, there is also an ideogram that corresponds to the current temperature — snowflake for too cold, danger sign for too hot, and thumbs up for that just-right range. Although this coaster is mostly 3D-printed, the mug sits on a slotted piece of aluminium that is removable for easy cleaning. This would be a good-looking and useful addition to any desk.

This is isn’t the first temperature-indicating beverage coaster we’ve seen. The most recent one ultimately used a probe, which is likely about as accurate (and messy) as you can get with these things.

PDP-10 Fits In Your Living Room

March 13, 2024 by Al Williams 8 Comments

[Oscar] at Obsolescence Guaranteed is well-known for fun replicas of the PDP-8 and PDP-11 using the Raspberry Pi (along with some other simulated vintage computers). His latest attempt is the PDP-10, and you can see how it looks in the demo video below.

Watching the video will remind you of every old movie or TV show you’ve ever seen with a computer, complete with typing noise. The PDP-10, also known as a DECsystem-10, was a mainframe computer that usually ran TOPS-10. These were technically “mainframes” in 1966, although the VAX eclipsed the system. By 1983 (the end of the PDP-10’s run), around 1,500 had been sold, including ones that ran at Harvard, Stanford, Carnegie Mellon, and — of course — MIT. They also found homes at CompuServe and Tymshare.

The original 36-bit machine used transistors and was relatively slow. By the 1970s, newer variants used ICs or ECL and gained some speed. A cheap version using the AM2901 bit-slice CPU and a familiar 8080 controlling the system showed up in 1978 and billed itself as “the world’s lowest cost mainframe.”

The Knight terminals were very unusual for the day. They each used a PDP-11 and had impressive graphics capability compared to similar devices from the early 1970s. You can see some of that in the demo video.

Naturally, anyone who used a PDP-10 would think a Raspberry Pi was a supercomputer, and they wouldn’t be wrong. Still, these machines were the launching pad for Adventure, Zork, and Altair Basic, which spawned Microsoft.

The cheap version of these used bitslice which we’ve been talking about lately. [Oscar] is also known for the KIMUno, which we converted into a COSMAC Elf.

2024 Home Sweet Home Automation: Simple Window Closer Relies On Gravity

March 13, 2024 by Kristina Panos 8 Comments

While most pet owners are happy to help out their furry friends, everyone has a limit. For [Gauthier], getting up to open or close the window every three minutes so their cat can go out on the balcony was a bridge too far, so they decided to take a crack at automating the window. The end result not only does the job, it’s extremely low-tech and pretty much invisible except when in use.

Of course, [Gauthier] didn’t arrive at this solution immediately. Their first thoughts went to RFID or perhaps a pressure sensor to detect the cats, coupled with something motorized to open and shut the window, like a belt or maybe a linear actuator. But ultimately, the system has to be robust, so that’s when [Gauthier] got the idea to employ gravity by using pulleys and weights.

Due to the configuration of the space and the shape of the window, [Gauthier] was able to to hide cable pretty well — you can’t really see anything when the window is closed. Be sure to check it out in action after the break. Continue reading “2024 Home Sweet Home Automation: Simple Window Closer Relies On Gravity” →

Review: The New Essential Guide To Electronics In Shenzhen

March 13, 2024 by Jenny List 15 Comments

The city of Shenzhen in China holds a special fascination for the electronic hardware community, as the city and special economic zone established by the Chinese government at the start of the 1980s it has become probably one of the most important in the world for electronic manufacturing. If you’re in the business of producing electronic hardware you probably want to do that business there, and if you aren’t, you will certainly own things whose parts were made there. From the lowly hobbyist who buys a kit of parts on AliExpress through the project featured on Hackaday with a Shenzhen-made PCB, to the engineer bringing an electronic product to market, it’s a place which has whether we know it or not become part of our lives.

First, A Bit Of History

A picture of booths in a Shenzhen market — These are the markets we have been looking for. Credit: Naomi Wu.

At a superficial level it’s very easy to do business there, as a quick trawl through our favourite Chinese online retailers will show. But when you’ve graduated from buying stuff online and need to get down to the brass tacks of sourcing parts and arranging manufacture, it becomes impossible to do so without being on the ground. At which point for an American or European without a word of Chinese even sourcing a resistor becomes an impossibly daunting task. To tackle this, back in 2016 the Chinese-American hardware hacker and author Andrew ‘bunnie’ Huang produced a slim wire-bound volume, The Essential Guide to Electronics in Shenzhen. This book contained both a guide to the city’s legendary Huaquanbei electronics marts and a large section of point-to-translate guides for parts, values, and all the other Chinese phrases which a non-Chinese-speaker might need to get their work done in the city. It quickly became an essential tool for sourcing in Shenzhen, and more than one reader no doubt has a well-thumbed copy on their shelves.

There are places in the world where time appears to move very slowly, but this Chinese city is not one of them. A book on Shenzhen written in 2016 is now significantly out of date, and to keep pace with its parts that have since chanced beyond recognition, an update has become necessary. In this endeavour the mantle has passed to the hardware hacker and Shenzhen native Naomi Wu, someone with many years experience in introducing the people, culture, and industries of her city to the world. Her updated volume, The New Essential Guide to Electronics in Shenzhen has been the subject of a recent crowdfunding effort, and I was lucky enough to snag one. It’s a smart hardcover spiral-bound book with a red and gold cover, and it’s time to open it up and take a look. Continue reading “Review: The New Essential Guide To Electronics In Shenzhen” →

A Solar-Powered Wristwatch With An ATtiny13

March 13, 2024 by Maya Posch 23 Comments

Wristwatches come in many shapes, sizes, and types, but most still have at least one thing in common: they feature a battery that needs to be swapped or recharged somewhere been every other day and every few years. A rare few integrate a solar panel that keeps the internal battery at least somewhat topped up, as environmental light permits.

This “Perpetual” wristwatch designed by [Serhii Trush] aims to keep digitally ticking along using nothing but the integrated photodiodes, a rechargeable LIR2430 cell, and a power-sipping face that uses one LED for each hour of the day.

The face of the perpetual wristwatch. (Credit: Serhii Trush)

The wristwatch’s operation is demonstrated in the linked video (in Ukrainian, auto-generated subtitles available): to read out the current time, the button in the center is pressed, which first shows the hour, then the minutes (in 5 minute intervals).

After this the ATtiny13 MCU goes back to sleep, briefly waking up every 0.5 seconds to update the time, which explains why there’s no RTC crystal. The 12 BPW34S photodiodes are enough to provide 2 mA at 0.5 V in full sunlight, which together keep the LIR2430 cell charged via a Zener diode.

As far as minimalistic yet practical designs go, this one is pretty hard to beat. If you wish to make your own, all of the design files and firmware are provided on the GitHub page.

Although we certainly do like the exposed components, it would be interesting to see this technique paired with the PCB watch face we covered recently.

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