Author: Al Williams

4599 Articles

$1 Graphene Sensor Identifies Safe Water

August 29, 2023 by 15 Comments

If you live in a place where you can buy Arduinos and Raspberry Pis locally, you probably don’t spend much time worrying about your water supply. But in some parts of the world, it is nothing to take for granted, bad water accounts for as many as 500,000 deaths worldwide every year. Scientists have reported a graphene sensor they say costs a buck and can detect dangerous bacteria and heavy metals in drinking water.

The sensor uses a GFET — a graphene-based field effect transistor to detect lead, mercury, and E. coli bacteria. Interestingly, the FETs transfer characteristic changes based on what is is exposed to. We were, frankly, a bit surprised that this is repeatable enough to give you useful data. But apparently, it is especially when you use a neural network to interpret the results.

What’s more, there is the possibility the device could find other contaminants like pesticides. While the materials in the sensor might have cost a dollar, it sounds like you’d need a big equipment budget to reproduce these. There are silicon wafers, spin coating, oxygen plasma, and lithography. Not something you’ll whip up in the garage this weekend.

Still, it is interesting to see a FET used this way and a cheap way to monitor water quality would be welcome. Using machine learning with water sensors isn’t a new idea. Of course, the sensor is one part of the equation. Monitoring is the other.

Retro Gadgets: The 1974 Breadboard Project

August 29, 2023 by 36 Comments

It is hard to imagine experimenting with electronics without the ubiquitous solderless breadboard. We are sure you have a few within arm’s reach. The little plastic wonders make it easy to throw together a circuit, try it, and then tear it down again. But, surprisingly, breadboards of that type haven’t always been around, and — for a while — they were also an expensive item. Maybe that’s what motivated [R. G. Cooper] to build Slip-n-Clip — his system for quickly building circuits that he published in a 1974 edition of the magazine Elementary Electronics.

The system isn’t really what you would think of as a breadboard today, but it was effective and certainly cheap to build. The biggest problem? It wasn’t something you’d use with DIP ICs. But in the early 1970s, you might not be building very much with ICs, and the ones you used might be in oddball transistor-like packages. Things were strange in the 70s!

A Brief History of Breadboards

In the very old days, people built radios and such on wooden substrates that were actually bread-cutting boards. That’s where the name came from. It was common to draw a diagram with the physical layout you had in mind, glue it to the board, and use it as a guide for building and troubleshooting. Wood was easy to drill and cut. A nail or a thumbtack would make dandy terminals. Probably the last time we saw that done was about a dozen years ago in Make Magazine. Even then, it was only a novelty — few people still build circuits like this, but you can see how [Colin] did it in the video below.

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It’s A Sander! No, It’s A Toothbrush! Relax, Relax, It’s Both

August 29, 2023 by 11 Comments

We always enjoy a project that transforms some common object into something useful for us. [Modelkitsdeluxe] fits the bill by modifying a power toothbrush into a miniature sander. If you want to practice your Spanish, you can watch the video below. Or you can try the automatically translated captions.

As you can guess from the user name, he is mainly interested in working with small models, but it struck us that this might also be useful for general 3D printing. Honestly, once you have the idea, there isn’t much to it. You mutilate a brush head that fits the toothbrush to accept a small sanding disk.

There are probably a dozen ways to attach your sandpaper or emery cloth to the head. [Modelkitdeluxe] used double-sided tape and Velcro. While we applaud the upcycling, we’ll probably stick with a hobby tool. Our toothbrush makes an annoying buzz every 30 seconds or so to remind you to move to another part of your mouth. That doesn’t seem like a great feature when doing precision sanding. On the other hand, you could probably yank the controller out of the toothbrush and use it for the motor, drive, and batteries to avoid that.

If you want to tackle that, here’s something to get you started. If sanding doesn’t turn your crank, maybe you can try turning your deadbolt.

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PCB Toaster Oven Solders Your Boards

August 28, 2023 by 15 Comments

Using a toaster oven to reflow PCBs isn’t anything new, but just using a toaster oven has some limitations. Making toast isn’t as complex as reflowing PCBs. [Nabil] decided to modify an oven to get better results. In fact, this was the second iteration and involved making a custom PCB to replace the one in the oven. You can see the unit in the video below.

Of course, unless you have the exact oven (a Breville BOV450XL), you won’t want to duplicate the board, but it might give you some good ideas. The new board has a 2.8-inch capacitive LCD, an ESP32, and a few sensors and actuators.

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Take A PEEK At This 3D Printer

August 28, 2023 by 28 Comments

Normally, when you think of PEEK in 3D printing, you think of a part made of PEEK, suitable for lower-temperature plastics. [ND-3D] has a different idea: printing with PEEK. You can get the details over on Hackaday.io, and there are a few YouTube videos below. Using a special controller and a halogen lamp, you can modify your own printer to use this exotic material often found in printer hot ends.

Logically, if PEEK is used near the hot end of regular printers, it must need a higher temperature to print. PEEK has a glass transition temperature of about 143 °C and melts at 343 °C. Compare this to PLA, which melts between 150 °C and 180 °C and has a glass transition temperature of only 60 °C.

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Linux On A Commodore 64

August 27, 2023 by 31 Comments

We are used to seeing Linux running on almost everything, but we were a bit taken aback to see [semu-c64] running Linux on a Commodore 64. But between the checked-out user name and the caveat that: “it runs extremely slowly and it needs a RAM Expansion Unit”, one can already start piecing together what’s happening here.

The machine running Linux is really a RISC-V32. It just so happens that the CPU is virtual, with the C64 pretending it is a bigger machine. The boot-up appears to take hours, so this is in no way practical, even though the comment is that optimization might be able to get a 10X speed up. It would still be about as slow as you can imagine.

To further add a layer of abstraction, the code hasn’t run yet on real Commodore hardware. Instead, it is running on an emulator. The emulator has “warp” mode to run faster than a real machine, and it is still slow. So think about that before you rush out to volunteer to boot this on your real hardware.

Tricks like this fall into the talking dog category. If a dog can talk, it isn’t that you think it will have something important to say. You just marvel that it can do it at all. Still, we get it. We spend a lot of time doing things at least as pointless. But at least it is fun!

Maybe emulate the whole thing in VR? Or maybe write some virtualization code for the C64 so you can emulate a Linux box and a quantum computer simultaneously.

Kitchen Steganography With Turmeric

August 26, 2023 by 12 Comments

It is a classic rite of passage for nerdy kids to write secret messages using lemon juice. If you somehow missed that, you can’t see the writing until you heat the paper up with, say, an old-fashioned light bulb. If you were a true budding spy, you’d write a boring normal letter with wide spacing and then fill in the blanks between the lines with your important secrets written in juice. This is a form of steganography — encoding secret messages by hiding them in plain sight. [Randomona] shares a different technique that seems to be way cooler than lemon juice using, of all things, turmeric. This isn’t like the invisible ink of our childhood.

That’s probably a good thing. We doubt an LED bulb makes enough heat to develop our old secret messages. [Ranomona’s] ink doesn’t use heat, but it uses a developer. That means you must make two preparations: the ink and the developer. The results are amazing, though, as shown in the video below.

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