Misc Hacks

4098 Articles

3D Print Yourself A Split Flap Display

February 20, 2025 by 8 Comments

Split flap displays! They’re mechanical, clickety-clackity, and largely commercially irrelevant in our screen-obsessed age. That doesn’t mean you can’t have a ball making one of your own, though! [Morgan Manly] did just that, with tidy results.

An ESP32 C3 SuperMini serves as the boss of the operation, running the whole display. The display is designed to be modular, so you can daisy chain multiple characters together to spell longer words. Each module has 37 characters, so it can display the alphabet, numerals 0 to 9, and a blank. Each module contains a 28BYJ-48 stepper motor for controlling the flaps, and a ULN2003 driver board to run it and a PCF8575 IO expander to handle communciation. An A3144 hall effect sensor is also used for positional feedback to ensure the display always shows the right character. The flap mechanism itself is relatively straightforward—a drum with all 37 flaps is until the correct character is reached, with the blank flaps hosting a magnet to trigger the aforementioned hall effect sensor. The flaps themselves are 3D-printed, with filament changes used to color the characters against the background.

If you’ve ever dreamed of building a flap-display clock or ticker, you needn’t dream of finding the perfect vintage example. You can just build your own! The added bonus is that you can make it as big or as small as you like. We’ve seen some interesting variations on the split flap concept recently, too. If you’re cooking up your own kooky electromechanical displays, don’t hesitate to let us know!

Microwave Motion Detector Notifies Your Smart Phone

February 20, 2025 by 16 Comments

Your garden variety motion detector uses IR, but these days, there are fancier technologies for achieving similar goals. If so desired, you can source yourself a microwave-based presence sensor instead. Indeed, like [N-08 Labs], you might like to whip one up into a basic intrusion detection system.

The idea is simple enough—take a RCWL-0516 microwave presence sensor, and set it up to detect motion and warn you when it happens. It’s a simple part to use—it simply drives a 3.3 volt logic output high if it detects someone or something. It basically just emits a microwave signal and detects a change in phase when someone or something—usually something fleshy—is in front of it. [N-08 Labs] simply hooked one up to an IO pin on an ESP8266, with the microcontroller board set up to communicate wirelessly with a Blynk IoT app, which then in turn fires off a smartphone notification that the sensor picked something up. The whole thing is built inside the shell of an AC adapter that provides power and let it easily hide in plain sight.

A project like this doesn’t just have to be for security purposes. You might even just use it to determine when your pet (or a racoon) is using the cat door, or similar. Indeed, we’ve seen great solutions to that particular problem, too. Video after the break.

Continue reading “Microwave Motion Detector Notifies Your Smart Phone” →

A Unique Linear Position Sensor Using Magnetostriction

February 18, 2025 by 16 Comments

To the extent that you’re familiar with magnetostriction, you probably know that it’s what makes big transformers hum, or that it’s what tips you off if you happen to walk out of a store without paying for something. But magnetostriction has other uses, too, such as in this clever linear position sensor.

Magnetostriction is just the tendency for magnetic materials to change size or shape slightly while undergoing magnetization, thanks to the tiny magnetic domains shifting within the material while they’re aligning. [Florian B.]’s sensor uses a side effect of magnetostriction known as the Wiedenmann effect, which causes a wire to experience a twisting force if a current pulse is applied to it in a magnetic field. When the current pulse is turned off, a mechanical wave travels along the wire to a coil, creating a signal. The difference in time between sending the pulse and receiving the reflection can be used to calculate the position of the magnet along the wire.

To turn that principle into a practical linear sensor, [Florian B.] used nickel wire stretched tightly down the middle of a PVC tube. At one end is a coil of copper magnet wire, while the other end has a damper to prevent reflections. Around the tube is a ring-shaped cursor magnet, which can move up and down the tube. An exciter circuit applies the current pulse to the wire, and an oscilloscope is used to receive the signal from the wire.

This project still appears to be in the prototype phase, as evidenced by the Fischertechnik test rig. [Florian] has been working on the exciter circuit most recently, but he’s done quite a bit of work on optimizing the cursor magnet and the coil configuration, as well as designs for the signal amplifier. It’s a pretty neat project, and we’re looking forward to updates.

If you need a deeper dive into magnetostriction, [Ben Krasnow] points the way.

Scrapyard Vacuum Dehydrator Sucks The Water From Hydraulic Oil

February 16, 2025 by 23 Comments

Anyone who has ever had the misfortune of a blown head gasket knows that the old saying “oil and water don’t mix” is only partially true. When what’s coming out of the drain plug looks like a mocha latte, you know you’re about to have a very bad day.

[SpankRanch Garage] recently found himself in such a situation, and the result was this clever vacuum dehydrator, which he used to clean a huge amount of contaminated hydraulic fluid from some heavy equipment. The machine is made from a retired gas cylinder welded to a steel frame with the neck pointing down. He added a fill port to the bottom (now top) of the tank; as an aside, we had no idea the steel on those tanks was so thick. The side of the tank was drilled and threaded for things like pressure and temperature gauges as well as sight glasses to monitor the process and most importantly, a fitting for a vacuum pump. Some valves and a filter were added to the outlet, and a band heater was wrapped around the tank.

To process the contaminated oil, [Spank] glugged a bucket of forbidden milkshake into the chamber and pulled a vacuum. The low pressure lets the relatively gentle heat boil off the water without cooking the oil too badly. It took him a couple of hours to treat a 10-gallon batch, but the results were pretty stark. The treated oil looked far better than the starting material, and while it still may have some water in it, it’s probably just fine for excavator use now. The downside is that the vacuum pump oil gets contaminated with water vapor, but that’s far easier and cheaper to replace that a couple hundred gallons of hydraulic oil.

Never doubt the hacking abilities of farmers. Getting things done with what’s on hand is a big part of farm life, be it building a mower from scrap or tapping the power of the wind.

Continue reading “Scrapyard Vacuum Dehydrator Sucks The Water From Hydraulic Oil” →

Cute Face Tells You How Bad The Air Quality Is

February 13, 2025 by 3 Comments

You can use all kinds of numbers and rating systems to determine whether the air quality in a given room is good, bad, or somewhere in between. Or, like [Makestreme], you could go for a more human visual interface. He’s built a air quality monitor that conveys its information via facial expressions on a small screen.

Named Gus, the monitor is based around a Xiao ESP32-C3. It’s hooked up with the SeeedStudio Grove air quality sensor, which can pick up everything from carbon monoxide to a range of vaguely toxic and volatile gases. There’s also a THT22 sensor for measuring temperature and humidity. It’s all wrapped up in a cute 3D-printed robot housing that [Makestreme] created in Fusion 360. A small OLED display serves as Gus’s face.

The indications of poor air quality are simple and intuitive. As “Gus” detects poor air, his eyelids droop and he begins to look more gloomy. Of course, that doesn’t necessarily tell you what you should do to fix the air quality. If your issue is pollution from outside, you’ll probably want to shut windows or turn on an air purifier. On the other hand, if your issue is excess CO2, you’ll want to open a window and let fresh air in. It’s a limitation of this project that it can’t really detect particulates or CO2, but instead is limited to CO and volatiles instead. Still, it’s something that could be worked around with richer sensors a more expressive face. Some will simply prefer hard numbers, though, whatever the case. To that end, you can tap Gus’s head to get more direct information from what the sensors are seeing.

We’ve seen some other great air quality projects before, too, with remarkably similar ideas behind them. Video after the break.

Continue reading “Cute Face Tells You How Bad The Air Quality Is” →

DIY Microwave Crucibles

February 12, 2025 by 16 Comments

You know the problem. You are ready to melt some metal in your microwave oven, and you don’t have any crucibles. Not to worry. [Shake the Future] will show you how to make your own. All you need is some silicon carbide, some water glass (sodium silicate), and some patience.

The crucible takes the shape of a glass container. Don’t get too attached to it because the glass will break during the crucible construction. You can also use 3D-printed forms.

Continue reading “DIY Microwave Crucibles” →

USB Hub-A-Dub-Dub: Weird Edge Cases Are My Ruin

February 3, 2025 by 67 Comments

The Universal Serial Bus. The one bus to rule them all.  It brought peace and stability to the world of computer peripherals. No more would Apple and PC users have to buy their own special keyboards, mice, and printers. No more would computers sprout different ports for different types of hardware. USB was fast enough and good enough for just about everything you’d ever want to plug in to a computer.

We mostly think of USB devices as being plug-and-play; that you can just hook them up and they’ll work as intended. Fiddle around around with some edge cases, though, and you might quickly learn that’s not the case. That’s just what I found when I started running complicated livestreams from a laptop…

Continue reading “USB Hub-A-Dub-Dub: Weird Edge Cases Are My Ruin” →