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Hackaday Links: February 21, 2021

February 21, 2021 by 6 Comments

Well, that was quite a show! The Perseverance rover arrived on Mars Thursday. Don’t tell the boss, but we spent the afternoon watching the coverage in the house on the big TV rather than slaving away in the office. It was worth it; for someone who grew up watching Jules Bergman and Frank Reynolds cover the Apollo program and the sometimes cheesy animations provided by NASA, the current coverage is pretty intense. A replay of the coverage is available – skip to about the 1:15:00 mark to avoid all the filler and fluff preceding the “Seven Minutes of Terror” main event. And not only did they safely deliver the package, but they absolutely nailed the landing. Perseverance is only about 2 km away from the ancient river delta it was sent to explore for signs of life. Nice shooting!

We’re also being treated to early images from Jezero crater. The first lowish-rez shots, from the fore and after hazard cameras, popped up just a few seconds after landing — the dust hadn’t even settled yet! Some wags complained about the image quality, apparently without thinking that the really good camera gear was stowed away and a couple of quick check images with engineering cameras would be a good idea while the rover still had contact with the Mars Reconnaissance Orbiter. Speaking of which, the HiRISE camera on the MRO managed to catch a stunning view of Perseverance’s descent under its parachute; the taking of that photo is an engineering feat all by itself. But all of this pales in comparison to a shot from one of the down-looking cameras in the descent stage, show Perseverance dangling from the skycrane just before touchdown. It was a really good day for engineering.

Would that our Earthly supply chains were as well-engineered as our Martian delivery systems. We’ve been hearing of issues all along the electronics supply chain, impacting a wide range of industries. Some of the problems are related to COVID-19, which has sickened workers staffing production and shipping lines. Some, though, like a fire at the AKM semiconductor plant in Japan, have introduced another pinch point in an already strained system. The fire was in October, but the impact on the manufacturer depending on the plant’s large-scale integration (LSI) and temperature-compensated crystal oscillators (TCXO) products is only just now being felt in the amateur radio market. The impact is likely not limited to that market, though — TCXOs pop up lots of gear, and the AKM plant made LSI chips for all kinds of applications.

What do you get when you combine a 3D-printer, a laser cutter, a CNC router, and a pick-and-place robot? Drones that fly right off the build plate, apparently. Aptly enough, it’s called LaserFactory, and it comes from MITs Computer Science and Artificial Intelligence Lab. By making different “bolt-on” tools for a laser cutter, the CSAIL team has combined multiple next-generation manufacturing methods in one platform. The video below shows a drone frame being laser-cut from acrylic, to which conductive silver paste is added by an extruder. A pick-and-place head puts components on the silver goo, solders everything together with a laser, and away it goes. They also show off ways of building up 3D structures, both by stacking up flat pieces of acrylic and by cutting and bending acrylic in situ. It’s obviously still just a proof of concept, but we really like the ideas presented here.

And finally, as proof that astronomers can both admit when they’re wrong and have fun while doing so, the most remote object in the Solar System has finally received a name. The object, a 400-km diameter object in a highly elliptical orbit that takes it from inside the orbit of Neptune to as far as 175 astronomical units (AU) from the Sun, is officially known as 2018 AG37. Having whimsically dubbed the previous furthest-known object “Farout,” astronomers kept with the theme and named its wayward sister “Farfarout.” Given the rapid gains in technology, chances are good that Farfarout won’t stay the Sun’s remotest outpost for long, and we fear the (Far)nout trend will eventually collapse under its own weight. We therefore modestly propose a more sensible naming scheme, perhaps something along the lines of “Farthest McFaraway.” It may not scale well, but at least it’s stupid.

Casio Watch Gets A MEMS Oscillator Upgrade

February 20, 2019 by 22 Comments

We’ve got to admit to being a bit of a Casio G-Shock watch geek. The big, chunky watches were every day carry items that survived everything we dished out, right up until the smartphone made wearing one seem redundant. But others continue to use and abuse G-Shocks, and some brave souls even hack them.

Replacing the standard quartz crystal with a temperature-compensated MEMS oscillator is one hack that [Alex] tried, and it appears to have worked out well. His project write-up doesn’t specify which MEMS oscillator was used, but we suspect it’s the SiT1552 TCXO. With its extremely small size, stability over a wide range of temperatures, and ultra-low power requirements, the chip is a natural choice to upgrade the stock 32.768-kHz quartz crystal of the watch. Trouble is, the tiny 1.5 mm x 0.8 mm chip-scale package (CSP) device presented some handling problems. After overcooking a few chips in the reflow oven, [Alex] was able to get one mounted to a tiny breakout board, which went into the space formerly occupied by the watch’s quartz crystal. He stole power for the TCXO from a decoupling capacitor, sealed the watch back up, and it’s back in service with better stability and longer battery life to boot. The video below shows the TCXO undergoing tests alongside the original quartz crystal and a comparatively huge DS3231 RTC module, just for fun.

[Alex]’s MEMS transplant seems a long way to go and a lot of fussy work for marginal gains, but who are we to judge? And it does make the watch susceptible to punking with a little helium, which might make things interesting.

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Drifting Instrument Presents Opportunity To Learn About Crystal Oscillators

June 5, 2018 by 11 Comments

Sure, we all love fixing stuff, but there’s often a fine line between something that’s worth repairing and something that’s cheaper in the long run to just replace. That line gets blurred, though, when there’s something to be learned from a repair.

This wonky temperature-compensated crystal oscillator is a good example of leaning toward repair just for the opportunity to peek inside. [Kerry Wong] identified it as the problem behind a programmable frequency counter reading significantly low. A TCXO is supposed to output a fixed frequency signal that stays stable over a range of temperatures by using a temperature sensor to adjust a voltage-controlled oscillator that corrects for the crystal’s natural tendency to vary its frequency as it gets hotter or colder. But this TCXO was pretty old, and even the trimmer capacitor provided was no longer enough to nudge it back in range. [Kerry] did some Dremel surgery on the case and came to the conclusion that adding another trim cap between one of the crystal’s leads and ground would help. This gave him a much wider adjustment range and let him zero in on the correct 10-MHz setting. [Mr. Murphy] still runs the show, though – after he got the TCXO buttoned up with the new trimmer inaccessible, he found that the frequency was not quite right. But going from 2 kHz off to only 2 Hz is still pretty good.

Whether it’s the weird world of microwave electronics or building a whole-house battery bank, it’s always fun to watch [Kerry]’s videos, and we usually end up learning a thing or two.

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Nanocounter: Frequency Counter With An Android UI

March 29, 2016 by 9 Comments

Have you ever started a project, run into an issue, started a new project to solve the issue, and completely forgot about the original project? [Andy] went down a rabbit hole of needing a tool to calibrate an MCU oscillator, but not having an accurate way to measure frequency. Most people would just buy a frequency counter and be done with it, but [Andy] decided to build his own.

The Nanocounter is an accurate, open source frequency counter that uses an Android phone as its display. It’s based on a high accuracy temperature compensated crystal oscillator (TCXO) fed into a phase locked loop (PLL) to create a high frequency, accurate reference clock.

This reference clock, along with the signal to be measured, are sent into a Xilinx FPGA which uses a method called equal precision measurement to determine the frequency. A STM32F072 microcontroller uses a SPI interface to get this data out of the FPGA, and controls the whole system. Finally, a cheap HC-06 Bluetooth module facilitates communication with an Android device.

The project achieves the goal of frequency counting, though [Andy] doesn’t remember what project sparked the idea to build it. (Classic yak shaving!) But the result is a great read of a detailed writeup, and you can watch a video of the Nanocounter in action after the break. That’s a win in our book.

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Improving The RTL-SDR

March 28, 2016 by 29 Comments

The RTL-SDR dongle is a real workhorse for radio hacking. However, the 28.8 MHz oscillator onboard isn’t as stable as you might wish. It is fine for a lot of applications and, considering the price, you shouldn’t complain. However, there are some cases where you need a more stable reference frequency.

[Craig] wanted a stable solution and immediately thought of a TCXO (Temperature Compensated “Xtal” Oscillator). The problem is, finding these at 28.8 MHz is difficult and, if you can find them, they are relatively expensive. He decided to make an alternate oscillator using an easier-to-find 19.2 MHz crystal.

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Mini Quadcopter Becomes Paper Airplane

February 20, 2016 by 12 Comments

Several of us got Cheerson CX-10 mini quadcopters last year. We even bought some more to hand out as Christmas gifts. If you haven’t seen them, they are diminutive little flyers about the size of an English muffin. Thee’s no denying they are fun to fly around the house, and they do annoy the dogs.

However, like all cute toys, you eventually get bored just buzzing the dogs and cats. [JustforFun Media TK] decided that his needed a facelift, so he converted it into a paper airplane. This isn’t the paper airplane you folded up in school, either. This is a slick-looking jet aircraft.

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The Three Dollar Frequency Standard

July 26, 2015 by 19 Comments

[Paulie] over on the EEVBlog forums picked up an inexpensive frequency counter on eBay and realized it was just a little bit off. As a result, he decided to build a frequency standard. His build wound up costing him about $3 and he shared the design and the software for it.

The hardware design is very simple: a TCXO (also from eBay), an ATMega8, a pushbutton, and a AA battery with DC to DC converter to power the whole thing. The software does all the work, providing frequencies from 10MHz down to a few hundred hertz (including some common audio test frequencies).

If you haven’t worked with a TCXO before, it is a crystal oscillator that includes a temperature compensation circuit to pull the crystal frequency up or down depending on temperature. Although crystal oscillators are pretty accurate already, adding this temperature compensation improves accuracy over the design temperature dramatically (typically, 10 to 40 times better than a naked crystal oscillator). If you want to learn more about TCXOs, here’s a good write-up.
A TCXO isn’t as good as an OCXO (where the first O stands for Oven). However, OCXOs cost more, are larger, and drain batteries (after all, it is running an oven). You can even hack your own OCXO, but it is going to cost more than $3.

If you want to see the real guts of one TCXO, check out the video.

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