Year: 2021

Drone And High Voltage Spin Up This DIY Corona Motor

October 19, 2021 by 5 Comments

The average Hackaday user could probably piece together a rough model of a simple DC motor with what they’ve got kicking around the parts bin. We imagine some of you could even get a brushless one up and running without too much trouble. But what about an electrostatic corona motor? If your knowledge of turning high voltage into rotational energy is a bit rusty, let [Jay Bowles] show you the ropes in his latest Plasma Channel video.

Like many of his projects, this corona motor relies on a few sheets of acrylic, a handful of fasteners, and a healthy dose of physics. The actual construction and wiring of the motor is, if you’ll excuse the pun, shockingly simple. Of course part of that is due to the fact that the motor is only half the equation, you still need a high voltage source to get it running.

An earlier version of the motor ended up being too heavy.

In this case, [Jay] is revisiting his earlier experiments with atmospheric electricity to provide the necessary jolt. One side of the motor is connected to a metallic mesh electrode that’s carried 100 m into the air by a DJI Mini2 drone, while the other side is hooked up to several large nails driven into the ground.

The potential between the two gets the motor spinning, and makes for an impressive demonstration, but it’s not exactly the most practical way to experiment with your new corona motor. If you’d rather get it running on the workbench, he also shows that a more traditional high voltage source like a Van de Graaff generator will do the job nicely. As an added bonus, it can even power the device wirelessly from a few feet away.

So what can you do with a corona motor? While [Jay] is quick to explain that these sort of devices aren’t exactly known for their torque, he does show that his motor is able to lift a 45 gram weight suspended from a string. That’s frankly more power than we expected, and makes us wonder if there is some quasi-practical application for this contraption. If there is we suspect it’ll be featured in a future Plasma Channel video, so stay tuned.

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POLF: Retro 3D Game Uses Only A Character Display

October 18, 2021 by 11 Comments

Got a retrocomputing itch? So does [David Given], and luckily for us all he indulged it by writing POLF: a first-person 3D game for the Commodore PET that uses only the system’s 40×25 text mode character display for visuals. It’s a fantastic achievement, considering that the 80s-era computer boasts 32 kB of memory and doesn’t even have a graphical display.

Each level has an 8×8 layout.

Each level in POLF is a small, maze-like room in which one’s goal is to play a sort of cross between billiards and golf, aiming to move the round “ball” object into the square “hole” object. The 3D view is rendered using raycasting, which is a way of efficiently drawing a workable 3D perspective using limited resources. Raycasting can only do so much, but as a method it works fantastically within its limitations, and there are useful tutorials out there that lay the process bare.

The GitHub repository for the project is here, and it should run on any 40-column screen PET with at least 16 kB of RAM. Watch it in action in the video, embedded below. (Hint: the little bar graphs under the compass headings at the bottom of the screen represent the player’s proximity to the ball and hole objects. )

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A Microwave Frequency Doubler

October 18, 2021 by 14 Comments

It is an age-old problem. You have a 2.5 GHz source and you want it at 5 GHz. You need a frequency doubler. [All Electronics Channel] has an interesting video that talks not only about the theory of such a device but shows a practical one made with copper strips on a blank PCB substrate.

A fun thing about microwaves is that even little strips of copper are circuit elements since the wavelength at 2.5 GHz is only 12cm. That means a quarter-wave stub is only 3 cm — just over an inch.

The construction technique used is simple and, as he points out, experimenting with a real circuit will give you much more feel for how these circuits work than just reading and working out the math.

The multiplier drives an amplifier into nonlinearity which, of course, generates harmonics. Then a bandpass filter selects the second harmonic. If you haven’t dealt with stub circuits before, you might want to read up on how a piece of copper connected at one end can act like an inductor, a capacitor, or even a tuned circuit.

If you want more detail on the copper tape technique, we can help. If you don’t want to double frequency, maybe you would prefer to try voltage.

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A game board with five LEDs and a hand shining a laser pointer at it

Laser Pointer And Arduino Make A Minimalistic Shooting Game

October 18, 2021 by 7 Comments

Video games are great and all, but sometimes you just want the thrill of manipulating actual objects in addition to watching action on a screen. This must have been the reason why Nintendo’s Duck Hunt became so popular despite the simplicity of its gameplay. Prolific hacker [mircemk] similarly made a computer-plus-physical game called “Laser Shooter“, which somehow reminds us of the good old NES game.

The game is based on an Arduino Nano, to which five LEDs as well as five photoresistors (LDRs) are connected. When the game is started, the LEDs light up at random and the player has a limited time to “shoot” the corresponding LDR with a laser pointer. This time limit is decreased as the game progresses, and the game is over once the player fails to hit the target on time. The “Game Over” message is accompanied by a sad tune, but luckily no giggling dog.

Complete schematics and code are available for anyone willing to try their hand at replicating or improving this game. And no, you can’t simply sweep your laser across the five LDRs all the time, because you lose if you shoot at the wrong target. For more laser pointer-based games, try this Laser Command clone or this laser tag badge system.

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Build A Dog Ball Launcher That Kinda Looks Like A Dog

October 18, 2021 by 12 Comments

The average garden dog will play fetch long beyond the average human’s endurance. If you want to keep your dog exercised without hurting your pitching arm, [brankly’s] automatic dog ball launcher might just be what you need.

The design is straightforward. The 3D printed housing features a large funnel into which a ball can be dropped. A servo then holds the ball while a pair of rollers are spun up by brushed DC motors. After two seconds, the servo releases the ball towards the rollers which launch the ball out of the machine. A Raspberry Pi Pico runs the show, controlling the timing of the ball launch and varying the motor speed to change the distance the ball is launched on each firing.

Files are available on Thingiverse for those eager to build their own. If you’re good, you might even be able to train your dog to drop the ball in themselves. We’ve seen similar builds before, too! Video after the break.

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The HP3458A: King Of Multimeters For Three Decades

October 18, 2021 by 16 Comments

[Marco] looks at a lot of meters. However, he considers the HP3458A the best even though they were introduced more than 30 years earlier in 1989. Someone donated one to [Marco] but it presented some error messages on startup and exhibited erratic behavior, so he had some repairs to do.

The error codes hinted there were issues with the multislope analog to digital converter and that’s what sets the meter apart, according to [Marco]. The meter has 8.5 digits, so a normal conversion stage won’t cut it.

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They Milk Cows, Don’t They?

October 18, 2021 by 90 Comments

You’ve no doubt heard of the many alternatives to cow’s milk that are available these days. Perhaps you’ve even tried a few of them in your quest to avoid lactose. Some coffeehouses have already moved on from soy milk, offering only oat or almond milk instead of 2% and whole. Their reasoning is that soy milk is a highly processed product that can’t be traced back to a single source, which stands in stark contrast to all those bags of single-origin coffee beans.

These nut-based alternatives kicked off what is known as the milk wars — the dairy industry’s fight against labeling plant-based dairy alternatives as ‘milk’ and so on. Well, now it’s getting even more interesting. A company called Perfect Day is making milk using microorganisms that secrete milk proteins. It may sound kind of gross, but it’s essentially microbial fermentation, which is the normal process by which bread, cheese, yogurt, wine, and beer are made.

To be fair, what Perfect Day and other companies are doing is precision fermentation using genetically engineered microorganisms in a bioreactor, so it’s a bit more involved than what you could probably pull off in the basement. Precision fermentation lies somewhere between two modern extremes — plant-based meat and cultured meat. The latter is actual animal tissue grown from stem cells, and is only available at high-end restaurants for exorbitant prices.

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