Author: Al Williams

4598 Articles

Striping A Disk Drive The 1970 Way

May 16, 2022 by 38 Comments

These days, mass storage for computers is pretty simple. It either uses a rotating disk or else it is solid state. There are a few holdouts using tape, too, but compared to how much there used to be, tape is all but dead. But it wasn’t that long ago that there were many kinds of mass storage. Tapes, disks, drums, punched cards, paper tape, and even stranger things. Perhaps none were quite so strange though as the IBM 2321 Data Cell drive — something IBM internally called MARS.

What is a data cell you might ask? A data cell was a mass storage device from IBM in 1964 that could store about 400 megabytes using magnetic strips that looked something like about a foot of photographic film. The strips resided inside a drum that could rotate. When you needed a record, the drum would rotate the strip you needed to the working part and an automated process would remove the strip in question, wrap it around a read/write head and then put it back when it was done.

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The Hair Dryer Monitor Fix

May 16, 2022 by 52 Comments

[Johnny] had a monitor that he was particularly fond of. The whole monitor appeared dead, and he decided to open it up and find out what could be wrong. He wound up fixing it — sort of — using a hairdryer. While we think his explanation of the problem is unlikely, we hate to armchair quarterback, and we applaud that he opened it up and got it working.

When something is dead, it is always a good idea to check the power and power supply, but that didn’t pan out in this case. In fact, the power supply board inside had what looked like reasonable voltage values throughout. The problem had to be something more subtle.

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Light Whiskers From Soap Bubbles Is Real Science

May 15, 2022 by 8 Comments

You might think that anything to do with a soap bubble is for kids. But it turns out that observing light scattering through a soap bubble produces unexpected results that may lead to insights into concepts as complex as space-time curvature. That’s what [stoppi] says in his latest experiment — generating “light whiskers” using a laser and a soap bubble. You can watch the video, below, but fair warning: if videos with only music annoy you, you might want to mute your speakers before you watch. On the other hand, it almost seems like a laser light show set to music.

The setup is simple and follows a 2020 Israeli-American research paper’s methodology. A relatively strong laser pointer couples to a fiber-optic cable through a focusing lens. The other end of the fiber delivers the light to the soap bubble, where it separates into strands that exhibit something called branched flow.

Our physics knowledge isn’t deep enough to explain what’s going on here. However, if you have an interest in reproducing this experiment, it doesn’t look like it takes anything exotic. The original paper has a lot to say on the topic and if that’s too heavy for you, there’s always the Sunday supplement version.

If there is ever a practical application for this, we’ll see an uptick in the design of bubble machines. Oddly, this isn’t the first time we’ve seen lasers married with bubbles.

Computer Thing Might Be Garbage

May 15, 2022 by 9 Comments

[Tech Time Traveller] has a lot of voices in his head this week, and most of them are worried about his wife’s reaction to him buying other people’s garbage. We don’t blame him, though. He bought it from an estate sale and it was billed as a TV typewriter. The device looked completely homebrewed from somewhere around the late 1970s to the early 1980s. It contains a mess of components obviously hand-built in a combination of neat construction and messy wiring.

[Tech] videos most of his tests and exploration to get the thing working and tested. Given its age and construction, it worked surprisingly well, although it did take a little work to get it back to complete function. In fact, he bought the device three years ago and is finally getting around to finishing the project and putting together the video.

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Upcycling A Flat Bed Scanner

May 15, 2022 by 34 Comments

[Piffpaffpoltrie] had a 20-year-old Acer flatbed scanner that they just couldn’t justify keeping. But it does seem a shame to throw away a working piece of gear. Instead, the old scanner became a light table. We’ll admit, as projects go, it isn’t the most technically sophisticated thing we’ve ever seen, but we do think it is a worthy way to upcycle something that would otherwise be filling up a landfill.

The scanner was old enough to have a CCFL light source inside. However, it was too small, so it came out along with many other components that may yet find use in another project. If you didn’t know , scanners are good sources for small stepper motors, straight rods, and first-surface mirrors.

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Running ARM Chips On Algae Power

May 14, 2022 by 17 Comments

What’s the size of an AA battery and can run an ARM Cortex M0+ for six months? Well… probably an AA battery, but obviously, that wouldn’t be worth mentioning. But researchers at Cambridge have built a cell of blue-green algae that can do the job.

As you might expect, the algae need light, since they generate energy through photosynthesis. However, unlike conventional solar cells, the algae continue to produce energy in the dark at least for a while. Presumably, the algae store energy during the day and release it at night to survive naturally-occurring periods of darkness.

Generating power from photosynthesis isn’t a new idea since photosynthesis releases electrons. A typical cell has gold electrodes and a proton exchange membrane of some kind. You can see a video from Cambridge below about generating electricity from photosynthesis. Keep in mind, of course, that the Cortex M0+ is capable of very low power operation. Don’t look for that algae-powered spot welder anytime soon.

People tend to get fixated on electricity as energy, but there are other ways to harness photosynthesis. For example, we’ve seen algae fueling a chicken hole in the past. Not to mention we’ve seen algae used to power a robot in a novel and non-electrical way.

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What’s In A Wattmeter?

May 13, 2022 by 2 Comments

The idea behind watts seems deceptively simple. By definition, a watt is the amount of work done when one ampere of current flows between a potential of one volt. If you think about it, a watt is basically how much work is done by a 1V source across a 1Ω resistor. That’s easy to say, but how do you measure it in the real world? [DiodeGoneWild] has the answer in a recent video where he tears a few wattmeters open.

There are plenty of practical concerns.  With AC, for example, the phase of the components matters. The first 11 minutes of the video are somewhat of a theory review, but then the cat intervenes and we get to see some actual hardware.

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