Misc Hacks

4076 Articles

Clever Mechanism Makes A Linear Control From A Rotary Hall Sensor

January 9, 2023 by 81 Comments

Every once in a while we stumble across something so simple yet so clever that we just have to call it out. This custom linear Hall effect sensor is a perfect example of this.

By way of backstory, [Nixieguy], aka [The Electronic Mercenary], offers up a relatable tale — in the market for suitable hardware to make the game Star Citizen more enjoyable, and finding the current commercial joystick offerings somewhat wanting, he decided to roll his own controllers. This resulted in the need for a linear sensor 100 mm in length, the specs for which — absolute sensing, no brushes or encoders, easily sourced parts — precluded most of the available commercial options, like linear pots. What to do?

The solution [Nixieguy] settled on was to use a Hall effect sensor and a diametrally magnetized neodymium ring magnet. The magnet is rotated through 180 degrees by a twisted aluminum bar, which is supported in a frame by bearings. A low-friction slider with a slot captures the bar; moving the slider along the length of the control rotates the bar, which rotates the magnet, which allows the Hall sensor to measure the angle of the magnetic field. Genius!

The parts for the prototype sensor are all made from 0.8-mm aluminum sheet stock and bent to shape. The video below shows the action better than words can describe it, and judging by the oscilloscope trace, the output of the sensor is pretty smooth. There’s clearly a long way to go to tighten things up, but the basic mechanism looks like a clear win to us.

Hats off to [Nixieguy] for this one, which we’ll surely be following for more developments. In the meantime, if you need to brush up on the Hall effect, [Al Williams] did a nice piece on that a while back.

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DIYson Lamp Hides Cables Between The Seams

January 2, 2023 by 52 Comments

[Steven Bennett] is so fond of Dyson’s new Lightcycle lamp that he’s decided to clone his own version in the spirit of the original. Dyson, however, knows what makes their lamp so special — so much that they patented their technique for tucking away the power wiring. Undaunted, [Steven]’s latest challenge has been to create a cable management solution that captures the elegance of the original without making a flat-out duplicate.

[Steven]’s latest update starts with the details of the original model’s patent. In a nutshell, Dyson’s elegance comes from both a flat cable (a flex PCB, perhaps?) and a magnetic interface that transfers power between the two primary structural beams. The latter half discusses [Steven]’s alternate solution: a miniature drag chain that can be 3D printed to arbitrary lengths. Like the flat flexible cable, this cable rides in the groove of the lamp’s two structural beams; but unlike the original, it spools outwards into a hoop on one end of its travel length. Overall [Steven] is quite happy with this result, and we think this solution gives the lamp a charm that’s distinctly original.

Capturing the design essence doesn’t just stop at wire management though. Have a look at some previous video logs in the series to get a sense of some of the other challenges faced in both heat dissipation and mechanical feel.

Wire management, when done well, scratches a design itch somewhere in the back of our heads. If you’re curious for more cable management solutions, have a look at some of these other tricks that use tape measure or involve a DIY coiling method.

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A model train car carrying a camera

2022 FPV Contest: Get The Train Driver’s View In Your N-Scale Railway

December 28, 2022 by 23 Comments

Model railroaders typically observe their project from high above. It would be neat to see what the world looks like to the residents of your little town, but getting down to their point of view is difficult, especially if you’re working in one of the smaller scales. For those working in the N scale, there’s now an easy way of observing your project as the train driver would see it: [Vassily98] managed to squeeze a wireless camera into an N-scale railcar.

The main challenge here was the extremely limited space available: the track in N-scale layouts is 9 mm wide, meaning that the whole system had to fit in just 23 x 20 mm2, the frontal area of a typical train car. One of the few cameras that fit within that profile was the RunCam Nano 4, which [Vassily98] connected to an ultra-tiny Team BlackSheep 5.8 GHz video transmitter.

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This WiFi Signal Strength Meter Ain’t Afraid Of No Ghosts

December 23, 2022 by 5 Comments

The original Ghostbusters movie is a classic that’s still delivering nearly 40 years after its release — just let that sink in for a minute. Almost every aspect of the film, from hand props to quotes, is instantly recognizable, even to people who haven’t based their lives on the teachings of [Venkman], [Stantz], and [Spengler]. To wit, we present this PKE meter-style WiFi scanner.

Of course, [Kevin McAleer]’s project is strictly in the “Just for Fun” category. But that doesn’t mean it’s not at least somewhat useful. The design is pretty close to the original PKE meter, with a little bit of creative license taken to make it easier to build. Guts include a Raspberry Pi Pico W and a generous 320×240 LCD display. The body of the meter is entirely 3D printed; design files are of course available. The meter’s arms are geared together to move with a single hobby servo.

On the software side, [Kevin]’s GUI lets users see a list of WiFi hotspots in the area and select one from the list. From there, the position of the arms is determined by the RSSI for the hotspot, similar to how the prop was supposed to indicate the proximity to a spook, specter, or ghost. There’s perhaps a bit of a missed opportunity by not adding LEDs to the arms, but we’ll let that slide.

The video below has full design and build details, but fair warning that it’s a bit on the long side. That’s probably just a reflection of how much work [Kevin] put into this, though. Of course, you may rather build a PKE meter that “actually” detects ghosts, in which case we’ve got you covered.

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More Detail On That Fantastic Lego OLED Brick

December 20, 2022 by 38 Comments

It’s always great when we get a chance to follow up on a previous project with more information, or further developments. So we’re happy that [“Ancient” James Brown] just dropped a new video showing the assembly of his Lego brick with a tiny OLED screen inside it. The readers are too, apparently — we got at least half a dozen tips on this one.

We’ve got to admit that this one’s a real treat, with a host of interesting skills on display. Our previous coverage on these bedazzled bricks was disappointingly thin on details, and now the original tweets even seem to have disappeared entirely. In case you didn’t catch the original post, [James] found a way to embed a microcontroller and a remarkably small OLED screen into a Lego-compatible brick — technically a “slope 45 2×2, #3039” — that does a great job of standing in for a tiny computer monitor.

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A Simple High-Fidelity DIY Mic Pre Amp

December 16, 2022 by 13 Comments

If you’re doing any serious work with microphones, you’ll typically find yourself in want of a dedicated preamp. [ojg] needed just such a thing for acoustic measurement duties, and set about working up a cheap DIY design by the name of ThatMicPre.

The design is based around the THAT1510 preamp IC, known for its good frequency response and low harmonic distortion and noise. The design is also compatible with THAT1512, SSM2019, and INA217 chips as well. [ojg] gave the design switch-controlled gain levels, providing greater accuracy than a potentiometer adjustment, and the ability to supply phantom power for mics that require it. The PCB is designed to rely on through-hole parts and common connectors for easy assembly.

The design is open source, and has already been built by others on the DIYAudio forums. Built into a simple case, it looks like a handsome and well-built piece of audio equipment. We’ve featured quite a few unique preamps over the years, and if you’ve been building your own, we’d love to see those too!

Building A Lamp To Help With Seasonal Depression

December 13, 2022 by 13 Comments

The sun plays a big biological role in our lives, regulating our circadian rhythms and doing a whole bunch more as well. Some people find the reduced sunlight of the winter months to have negative emotional effects, and rely on artificial lighting to counteract this. [Samasrinivas] built a lamp of their own design for this very purpose.

The lamp is constructed around an abstract sculptural form made in air-dry clay. Light is provided via a string of Neopixel RGBW LEDs. Run by an Adafruit Feather Huzzah, they’re programmed to trigger with the sunrise to provide a bright light in the morning on grey days when the outside world isn’t quite delivering the same. The Adafruit queries an online weather API to get the right sunrise time every day without requiring user intervention. The lamp can also be programmed to provide warm light during later hours.

We’ve featured a few circadian lighting projects before, including one that goes for a whole-of-house effect with smart bulbs. For some, they’re a valuable way to help boost mood and maintain consistent sleep cycles. Video after the break.

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