Cool Face Mask Turns Into Over-Engineered Headache

July 31, 2022 by Ryan Flowers 13 Comments

Seeing his wife try to use a cool face mask to get through the pain of a migraine headache, [Sparks and Code] started thinking of ways to improve the situation. The desire to save her from these debilitating bouts of pain drove him to make an actively cooled mask, all the while creating his own headache of an over-engineered mess.

Void spaces inside the printed mask are filled with chilled water.

Instead of having to put the face mask into the refrigerator to get it cold, [Sparks and Code] wanted to build a mask that he could circulate chilled water through. With a large enough ice-filled reservoir, he figured the mask should be able to stay at a soothing temperature for hours, reducing the need for trips to the fridge.

[Sparks and Code] started out by using photogrammetry to get a 3D model of his wife’s face. Lack of a compatible computer and CUDA-enabled GPU meant using Google Cloud to do the heavy lifting. When they started making the face mask, things got complicated. And then came the unnecessary electronics. Then the overly complicated and completely unnecessary instrumentation. The… genetic algorithms? Yes. Those too.

We won’t spoil the ending — but suffice it to say, [Sparks and Code] learned a cold, hard lesson: simpler is better! Then again, sometimes being over-complicated is kind of the point such as in this way-too-complex gumball machine.

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Building A Tube-Based Stereo Amp, In Classic Style

July 31, 2022 by Donald Papp 35 Comments

It’s not every day we see the results of someone putting their own spin on a vintage tube amp, but that’s exactly what [lens42] did in creating the McIntosh 217, created as a “mini” version of the McIntosh MC275, a classic piece of audio equipment. Both are pictured next to each other, above.

When it comes to vintage hi-fi stereo amplifiers, two units had particular meaning for [lens42]: the McIntosh MC275 Power Amp, and the Dynaco ST35. The Dynaco was a more budget-friendly amplifier, but looked like a plain box. The McIntosh, however, proudly showed off its tubes and transformers in all their glory. The “McIntosh 217” is design-wise basically a smaller McIntosh MC275, with the innards of a Dynaco ST35.

With so much needing to be designed from the ground up, CAD was invaluable. Component layout, enclosure design, and even wiring and labeling all had to be nailed down as much as possible before so much as heating up the soldering iron. Even so, there were a few hiccups; a vendor had incorrect measurements for a tube socket which meant that the part would not fit. A workaround involved modifying the holes and as luck would have it, the change wasn’t an eyesore. Still, [lens42] reminds us all that whenever you can, have the required parts in-hand for confirmation of dimensions before sending CAD files off for cutting or fabrication.

Many of us can relate to the fact that the whole project was a labor of love and made no real financial sense, but the end result is fantastic, and creating such a thing is something all of us — not just chasers of that elusive “tube sound” — can appreciate.

Turning A Pair Of Syringes Into A Tiny Water Pump

July 31, 2022 by Danie Conradie 6 Comments

There is something inherently fascinating about tiny mechanical devices, especially when you’re used to seeing much larger versions. This is the case with [Penguin DIY]’s tiny centrifugal water pump built from 5 ml syringes.

The pump is powered by a small 8 mm diameter brushed DC motor, likely the same type that is used for small toy-grade quadcopters. The tiny impeller is a section of the syringe’s original plunger, with its cross-shaped body acting as the impeller blades. [Penguin DIY] first experimented with the original plunger seal to protect the motor from water, but it quickly melted from friction with the spinning shaft. Silicone sealant was used instead, and the motor shaft was covered with a layer of oil to prevent the sealant from sticking to it. Then the blob of sealant was flattened with a translucent plastic disc to allow clearance for the impeller.

A hole was drilled in the side of the syringe where the impeller sits, and a nozzle cut from the tip of another syringe was glued in place as the outlet. It’s notoriously difficult to get anything to stick to polypropylene syringes, but [Penguin DIY] says in the comments he was able to find an “organic superglue” that worked. With the motor and impeller inserted, the remaining space was also sealed with silicone.

This tiny pump packs a surprising amount of power, and was able to empty a 1.5 l bottle in about one minute with enough pressure to send the jet of water flying. There are still some issues that need to be addressed, though. With the motor completely sealed, it could burn itself quite quickly. A commenter also mentioned that it might suck water into the motor past the shaft after a hot run, as the air inside the motor cools and contracts. Even so, this little pump might be practical for applications that only require short runs, like watering potted plants. If you need more power you could always 3D print a larger pump.

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Upgraded Film Scanner Handles Bigger Formats At No Cost

July 30, 2022 by Donald Papp 2 Comments

Film scanners are a useful tool for digitizing slides and negatives, and the Plustek 8100 that [Christian Chapman] had was capable, but limited to small format film only. Rather than pay for a much more expensive medium format scanner that could handle 120 film, he modified his 8100 to accomplish the same thing with a combination of good old software and hardware tampering.

On the software side, [Christian] modified a driver for the Plustek 8100 so that it sweeps the scan head further than usual. At the application level, to scan medium format frames, it does a total of four scans: one for each quadrant. The results get stitched together in software with a thoughtfully-designed shell script that provides previews and handles failures and restarts gracefully.

Hardware-wise, the scanning carriage needs modification to ensure nothing interferes with the scan head as it moves further than originally designed. Some CAD and 3D printing made short work of this. Incidentally, this hardware mod is an excellent demonstration of one of the core strengths of 3D printing: the ability to make geometrically-straightforward objects that would nevertheless be troublesome or impractical to construct in any other way.

What’s The Time? It’s Casino’clock!

July 30, 2022 by Sven Gregori 6 Comments

As the saying goes, nothing can be said to be certain, except death, taxes, and the never-ending inventiveness of clock hacks. No matter how tried and proven a concept is, someone will always find a new twist for it. Case in point: notorious clock builder [Shinsaku Hiura] took the good old split-flap display approach, and mixed things up by using a deck of playing cards to actually represent the time.

Technically, the clock works just like a regular flip clock, except that only the upper half of the split-flap is used to display the digits, while the lower half is showing the cards’ backsides. Other than that, the mechanics are the same: a set of hinges holding the cards are arranged on a rotor that’s moved by a stepper motor until the correct digit is shown (STLs available on Thingiverse). Aces low, Jokers are zeroes, and the queen strikes at noon.

At the center of it is an ESP32 that controls each digit’s motor driver, and retrieves the time via WiFi, keeping the general component count conveniently low. Of course, one option is to arrange the cards in their order to keep rotations at a minimum, but let’s be real, the flapping sound is half the fun here. So instead, [Shinsaku Hiura] arranged the cards randomly and mapped it in the code accordingly. You can see it all in action, along with some additional design information, in the video after the break.

For some more of his clock creations, check out this different flip clock approach and the Hollow Clock. But if the future is of more interest to you than the present, here’s a matching Tarot deck.

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USB Drive Keeps Your Secrets… As Long As Your Fingers Are Wet?

July 30, 2022 by Donald Papp 27 Comments

[Walker] has a very interesting new project: a completely different take on a self-destructing USB drive. Instead of relying on encryption or other “visible” security features, this device looks and works like an utterly normal USB drive. The only difference is this: if an unauthorized person plugs it in, there’s no data. What separates authorized access from unauthorized? Wet fingers.

It sounds weird, but let’s walk through the thinking behind the concept. First, encryption is of course the technologically sound and correct solution to data security. But in some environments, the mere presence of encryption technology can be considered incriminating. In such environments, it is better for the drive to appear completely normal.

Toggling the chip enable (CE) pin will hide the drive’s contents.

The second part is the access control; the “wet fingers” part. [Walker] plans to have hidden electrodes surreptitiously measure the resistance of a user’s finger when it’s being plugged in. He says a dry finger should be around 1.5 MΩ, but wet fingers are more like 500 kΩ.

But why detect a wet finger as part of access control? Well, what’s something no normal person would do right before plugging in a USB drive? Lick their finger. And what’s something a microcontroller should be able to detect easily without a lot of extra parts? A freshly-licked finger.

Of course, detecting wet skin is only half the equation. You still need to implement a USB Mass Storage device, and that’s where things get particularly interesting. Even if you aren’t into the covert aspect of this device, the research [Walker] has done into USB storage controllers and flash chips, combined with the KiCad footprints he’s already put together means this open source project will be a great example for anyone looking to roll their own USB flash drives.

Regular readers may recall that [Walker] was previously working on a very impressive Linux “wall wart” intended for penetration testers, but the chip shortage has put that ambitious project on hold for the time being. As this build looks to utilize less exotic components, hopefully it can avoid a similar fate.

Re-reclaimed From Nature: Resurrecting A DT80 Terminal

July 30, 2022 by Sven Gregori 6 Comments

When Datamedia announced their new DT80 terminal as a VT100 killer back in 1979, they were so confident of its reliability, they threw in a full one-year warranty. Now, decades later, that confidence is once more put to the touch after [RingingResonance] fished one such terminal out of a creek by an old illegal dumping site. Not knowing what to expect from the muck-ridden artifact, his journey of slowly breathing life back into the device began.

Considering the layers of mud and roots already growing all over the main board, one can only assume how long the terminal has actually been in there. But cleaning it from all that was only the beginning: some components were missing, others turned out to be broken, including some of the ROMs, which [RingingResonance] speculates may have been caused by lightning which determined the DT80’s fate in the first place.

That’s when the adventure really started though, digging deep into the terminal’s inner life, eventually writing a debugger and own firmware for it. That code, along with all other research, notes, and links to plenty more pictures can be found in the GitHub repository, and is definitely worth checking out if you’re into the technologies of yesteryear.

Despite the DT80’s claimed superiority, the VT100 prevailed and is the terminal that history remembers — and emulates, whether as tiny wearable or a full look-alike. But this fall into oblivion was also part of [RingingResonance]’s motivation to keep going forward restoring the DT80. Someone had to. So if you happen to have anything to contribute to his endeavours or share with him, we’re sure he will appreciate you reaching out to him.

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