Scratch Your Itch To Program A Microcontroller

February 3, 2023 by Al Williams 19 Comments

One of the fun things about “old school” computers is that it was fairly easy to get kids into programming them. The old Basic interpreters were pretty forgiving, and you could do some clever things easily with very little theory or setup. These days, you are more likely to sneak kids into programming via Scratch — a system for setting up programs via blocks in a GUI. Again, you can get simple results simply. With Scratch or Basic, complex things have a way of turning out complex, but that’s to be expected. If you want to try a Scratch-inspired take on microcontroller programming, check out MicroBlocks. It will work with several common boards, including the micro:bit and the Raspberry Pi Pico. You can use it in a browser or download versions for Linux, Windows, Mac, or even Chromebooks.

You can see a video below about the micro:bit version from a year ago. The tool is advancing, so you’ll find many new features compared to the video, but it will still give you an idea of what’s happening.

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Electron Microscope Conversion Hack

February 1, 2023 by Al Williams 7 Comments

Some of you probably know this already, but there’s actually more than one kind of electron microscope. In electronics work, the scanning electron microscope (SEM) is the most common. You hit something with electrons and watch for secondary electron emissions. However, biologists more often use a TEM — a transmissive electron microscope — which passes electrons through a sample to image it. [Breaking Taps] built a small device to convert his SEM into a TEM.

One key idea is that in a SEM, the beam’s position on the target is the only thing that matters. Any secondary electron detected is a result of that spot’s composition, no matter where you collect them. Common detectors pick up back-scattered electrons bouncing back toward the electron source. There are also low-energy electrons bouncing off in random directions, depending on the topology of the target.

The slow electrons can be attracted by a single detector that has a strong positive charge. TEM doesn’t detect secondary electron emissions. Instead, it passes electrons through a target and collects the ones that pass through a very thin sample using a screen that glows when electrons hit it.

The idea, then, is to create a STEM-SEM device. There’s a sample holder and an angled reflector that shoots electrons passing toward the SEM’s detector. The back-scatter detector is not used, and a shield prevents the detector from seeing secondary emissions from the target itself.

You can buy these, but they are well over $1,000, so in true hacker fashion, [Breaking Taps] made his own. You could, too, but you’d need a pretty good machine shop and — oh yeah — a scanning electron microscope.

While we have seen some home labs with electron microscopes, you need some high-tech vacuum and high-voltage gear, so it isn’t too common. Armed with a STEM, you can even see the shadows of atoms.

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DIY Adjustable Wrench? Nuts!

February 1, 2023 by Al Williams 12 Comments

What do you do if you want a tiny little adjustable wrench? If you’re [my mechanics] you build your own. Where do you get the stock metal? Well, he started with an M20 nut. A few milling operations, a torch, some pliers, and work with a vice resulted in a nice metal blank just the right size to make each part of the wrench, including a new nut for the adjustment.

Want to do this yourself? If you do, we hope you have a well-equipped machine shop. You should also be comfortable working with red-hot metal. Overall, it is an amazing piece of work, and you can watch the whole process in the video below.

Honestly, precision metalworking is a little out of our comfort zone. Like the recent wood bending we’ve seen, we always think, “Yeah, I could so do that!” Then we realize that we really couldn’t. But still fun to watch and maybe a few ideas we might be able to apply next time we have to bend a little metal.

The wrench is a scale model of a larger one, and it looks great. We would have liked to see it in use with a tiny nut, but we imagine it would work just fine. If you get excited about making things from a single piece of metal, may we suggest a nutcracker?

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RF Spectrometer Sees Inside

January 30, 2023 by Al Williams 7 Comments

Spectrometry is a well-known technique or, more correctly, a set of techniques. We usually think of it as the analysis of light to determine what chemicals are producing it. For example, you can tell what elements are in a star or an incandescent based on the spectrum of light they emit. But you can also do spectroscopy with other ranges of electromagnetic radiation. [Applied Science] shows how to make an RF spectroscope. You can see the video below.

An oscilloscope-resident function generator creates a signal that he feeds to an amplifier because you need a fair amount of power going out. However, you also need to sense a very tiny amount of power coming back, and that requires a special circuit that will block high-power signals while passing low-level signals.

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Retro Gadgets: The CB Cell Phone

January 30, 2023 by Al Williams 45 Comments

There was a time when one of the perks of having a ham radio in your car (or on your belt) was you could make phone calls using a “phone patch.” In the 1970s, calling someone from inside your parked car turned heads. Now, of course, it is an everyday occurrence thanks to cell phones. But in 1977, cell phones were nowhere to be found. Joseph Sugarman, the well-known founder of JS&A, saw a need and wanted to fill it. So he offered the “PocketCom CB” which was billed as the “world’s smallest citizens band transceiver.” You can see the full-page ad from 1977 below.

Remember that this is from an era when ICs that could operate at 30 MHz were not the norm, so you have to temper your expectations. The little unit was 5.5 in by 1.5 in and less than an inch thick. That’s actually not bad, but you had — optimistically — 100 mW of output power. They claimed the N cell batteries would last two weeks with average use, but we imagine a lot less as soon as you start transmitting. The weight was 5 oz, but we suspect that is without the batteries.

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Inside A 1940’s Spy Radio

January 30, 2023 by Al Williams 18 Comments

The RCA CR-88 was a radio receiver made to work in top-secret government eavesdropping stations. As you might expect, these radios are top-of-the-line, performance-wise, at least when they are working correctly. [Mr. Carlson] has one on his bench, and we get to watch the show on his recent video that you can see below.

Interestingly, [Mr. Carlson] uses some Sherlock Holmes-like deductive reasoning to guess some things about the radio’s secret history. The radio’s design is decidedly heavy-duty, with a giant power transformer and many tubes, IF transformers, and large filter capacitors.

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The Times They Are A-Chaining

January 28, 2023 by Al Williams 6 Comments

If [Bob Dylan] had seen [Pgeschwi]’s bike chain clock, it might have influenced the famous song. The clock uses a stepper motor and a bike chain to create a clock that has a decidedly steampunk vibe. Despite the low-tech look, the build uses 3D printing and, of course, a bike chain.

The clock doesn’t just show the time. There is a contraption to show the day of the week, and a pendulum shows the current phase of the moon. The visible wiring is all old-school brass wire on the wood base. [Pgeschwi] is considering changing out all the 3D printed parts for brass ones, so this may be just an early prototype of the final product, but it still looks great.

The design used common tools, including Tinkercad and an online gear generation tool. There are a lot of details you wouldn’t suspect until you tried to build something like this yourself. For example, making the chain reliably go in both directions required a timing belt to synchronize the top gears. Getting the numbers on the chain to pass by the gears.

It is hard to tell from the picture, but there’s an LED under the 10-minute marks that shows the unit’s digits of the time. There are no markings for it yet, but in the picture, the time is actually 4:09.

We love unusual clocks, and we see plenty of them. From Fibonacci clocks to magnetic field line clocks, we love them all.