OpenCV Knows Where Your Hand Is

December 23, 2021 by 1 Comment

We have to say, [Murtaza]’s example game in his latest video isn’t very exciting. However, the OpenCV technique he uses to track a hand and determine its distance from a single camera is pretty interesting. The demo shows a random button on the screen and you have to use your hand to press the button which then moves so you can try again. The hand measurement seems accurate to a few centimeters which is good enough for many applications.

The Python code is actually quite straightforward. Essentially, the software tracks your hand and by estimating its relative size to determine how far away it is. Of course, your hand might also rotate, and [Murtaza] works through all the cases step-by-step. If we wanted to know a distance, we’d probably turn to ultrasonics or a time of flight sensor. The problem is, those sensors can’t tell your hand from anything else that happens to be in front of it. The use of a single camera to track and locate is pretty impressive.

If you haven’t used OpenCV before, the channel has a lot of tutorials and they are all worth watching. Computer vision is a great technique and can replace a lot of things in some applications. GPS, for example. Or, try this creepier tracking application next Halloween.

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How To Get Into Cars: E85 Fuel

December 23, 2021 by 33 Comments

If you’ve spent any time around the modified car scene in the last few years, you’ve probably heard about E85. Maybe you’ve even noticed a sweet smell emanating from the pitlane, or heard people cracking jokes about “corn juice.”

The blended fuel, which combines alcohol and traditional gasoline, can have significant performance benefits if used properly. Today, we’ll explore what those are, and how you can set your ride up to run on E85.

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Belt-drive 3D-printer extruder

Back-to-Back Belts Drive Filament In This Unique Extruder Design

December 23, 2021 by 18 Comments

It’s hard to say when inspiration will strike, or what form it’ll take. But we do know that when you get that itch, it’s a good idea to scratch it, because you might just end up with something like this cool new design for a 3D printer extruder as a result.

Clearly, the world is not screaming out for new extruder designs. In fact, the traditional spring-loaded, toothed drive wheel on a stepper really does the job of feeding filament into a printer’s hot end just fine, all things considered. But [Jón Schone], aka Proper Printing on YouTube, got the idea for his belt-drive extruder from seeing how filament manufacturers handle their products. His design is a scaled-down version of that, and uses a pair of very small timing belts that run on closely spaced gears. The gears synchronize the movement of the two belts, with the filament riding in the very narrow space between the belts. It’s a simple design, with the elasticity of the belt material eliminating the need for spring pre-loading of the drive gears.

Simple in design, but not the easiest execution. The video below tells [Jón]’s tale of printing woe, from using a viscous specialty SLA resin that was really intended for a temperature-controlled printer, to build tank damage. The completed extruder was also a bit too big to mount directly on the test printer, so that took some finagling too. But at the end of the day, the idea works, and it looks pretty cool doing it.

As for potential advantages of the new design, we suppose that remains to be seen. It does seem like it would eliminate drive gear eccentricity, which we’ve seen cause print quality issues before.

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A Simple 3D Printed Gear Clock Shows Off How It Works

December 23, 2021 by 15 Comments

Analog clocks are beautiful things inside, using ornate gear trains to keep track of time in a dance of mechanical beauty. However, all too often, the complexity is hidden inside. This gear clock design from [Tada3], however, proudly shows off its workings.

A small stepper motor is used to run the clock’s movement, a small part of the 28BYJ-48 variety. The motor is driven once per second, making the gear train tick along in a rather compelling way that is somehow more visually interesting. Of course, with some modification to the design, continuous motion could easily be done as well.

The stepper motor is driven by an Arduino Nano, which also handles the timekeeping. One thing that’s missing is a real-time clock, something that should be added to the design if you wish it to keep accurate time. As it is, the included Arduino sketch simply uses the delay() function to time the stepping of the motor. It makes the clock tick along, but will quickly drift out of sync.

The design was also recreated in a YouTube video by [Mirko Pavleski], showing that the files are of suitable quality for building your own at home. We’ve seen some gear clock designs before, too, from the laser-cut to the neatly-nested. Video after the break.

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Experiments With A Nernst Lamp

December 22, 2021 by 14 Comments

Every biography of Edison talks about how the secret to the incandescent lamp was to remove the air from the bulb. That’s true when you use conventional filaments, but a man named Nernst found that using a filament that was already oxidized would allow you to create a lamp that would operate fine in the normal atmosphere. [Jaynes Network] takes a look at these oddities which date back to the 1800s in a recent video that you can see below.

The lamps use a ceramic filament, but the downside is that the filament needs to be hot to allow the lamp to work. The experiment takes a zirconium oxide rod and attempts to light it up. The heat source is a propane torch.

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New Holographic Display Hacks The Light Field

December 22, 2021 by 27 Comments

[Petapixel] has an interesting post about a startup company’s new holographic display that claims to be “indistinguishable from reality.” The company behind it, Light Field Labs, claims their system requires no glasses and handles different angles.

You can see a bit in the [C|Net] video below, but — of course — being on YouTube, you can’t get a sense for how good the 3D effect is.

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Frame Antenna Works The Low Bands

December 22, 2021 by 10 Comments

The lower the frequency of radio transmission, the more antenna that will be needed in general. [OM0ET] wanted to work the 80M to 20M ham bands and decided to turn to a frame antenna. You can see the project in the video below.

The antenna looks a lot like a magnetic loop antenna. The one in the video has seven loops forming a 520mm square. The loop is, of course, an inductor and by removing some insulation, the operator can clip a lead at different points to control the inductance. A variable capacitor resonates the antenna, so there is definitely tuning required.

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