Misc Hacks

4137 Articles

Toothbrush Speed Controller Secrets Revealed

May 18, 2023 by 21 Comments

Typically, when we want to build something with a DC motor, we might grab a bunch of AAs, or a single lithium cell at the very least. Electric toothbrushes often run on more humble power sources, like a single NiMH battery. They’re designed to get useful motion out of just 1.2V, and [Marian Hryntsiv] has taken a look at what makes them tick.

The article focuses on an electric toothbrush built around the Low Voltage GreenPAK™ SLG47513 chip. It’s designed to work at voltages from just 1 to 1.65 V. To make the most of the limited power available, the toothbrush stays in sleep mode most of the time when it’s not working in oral health.

[Marian] steps through the various parts of the circuit, and also explains the unique functionality baked into the brush. Of particular interest are the timer routines that guide the user through brushing each section of the mouth in turn, before a notification that tells them that 2 minutes of brushing time has elapsed. There’s also a useful explanation of the inductive charging method used.

Electric toothbrushes may be mundane home items today, but they’re an example of a product that has largely already been optimized to the nth degree. Until laser-based plaque removal or enamel regeneration technology gets off the ground, this is as good as it gets. We can dream, though!

 

Hackaday Prize 2023: A DIY Voice-Control Module

May 15, 2023 by 13 Comments

If science fiction taught us anything, it’s that voice control was going to be the human-machine interface of the future. [Dennis] has now whipped up a tutorial that lets you add a voice control module to any of your own projects.

The voice control module uses a Raspberry Pi 4 as the brains of the operation, paired with a Seeed Studio ReSpeaker 4-microphone array. The Pi provides a good amount of processing power to crunch through the audio, while the mic array captures high-quality audio from any direction, which is key to reliable performance. Rhasspy is used as the software element, which is responsible for processing audio in a variety of languages to determine what the user is asking for. Based on the voice commands received, Rhasspy can then run just about anything you could possibly require, from sending MQTT smart home commands to running external programs.

If you’ve always dreamed of whipping up your own version of Jarvis from Iron Man, or you just want a non-cloud solution to turn your lights on and off, [Dennis’s] tutorial is a great place to start. Video after the break.

Continue reading “Hackaday Prize 2023: A DIY Voice-Control Module” →

Hackaday Prize 2023: Eye-Tracking Wheelchair Interface Is A Big Help

May 14, 2023 by 2 Comments

For those with quadriplegia, electric wheelchairs with joystick controls aren’t much help. Typically, sip/puff controllers or eye-tracking solutions are used, but commercial versions can be expensive. [Dhruv Batra] has been experimenting with a DIY eye-tracking solution that can be readily integrated with conventional electric wheelchairs.

The system uses a regular webcam aimed at the user’s face. A Python script uses OpenCV and a homebrewed image segmentation algorithm to analyze the user’s eye position. The system is configured to stop the wheelchair when the user looks forward or up. Looking down commands the chair forward. Glancing left and right steers the chair in the given direction.

The Python script then sends the requisite commands via a TCP connection to an ESP32, which controls a bunch of servos to move the wheelchair’s joystick in the desired manner. This allows retrofitting the device on a wheelchair without having to modify it in an invasive manner.

It’s a neat idea, though it could likely benefit from some further development. A reverse feature would be particularly important, after all. However, it’s a great project that has likely taught [Dhruv] many important lessons about human-machine interfaces, particularly those beyond the ones we use every day. 

This project has a good lineage as well — a similar project, EyeDriveOMatic won the Hackaday prize back in 2015.

The HackadayPrize 2023 is Sponsored by:

Your Childhood Inventions Brought To Life

May 12, 2023 by 8 Comments

If you are the kind of person who reads Hackaday, you probably spent time in school doodling little design day dreams. [Allen Pan] gets it, and he’s taken it upon himself to make some of those daydreams into reality. You can see how it worked out — or didn’t — in the video below.

The video starts out with suction cup boots for walking on the ceiling, a laser sword made with a mirror, a plunger gun, and lawnmower boots. Some of these were more successful than others.

Continue reading “Your Childhood Inventions Brought To Life” →

Low-Frequency DC Block Lets You Measure Ripple Better

May 10, 2023 by 12 Comments

We all know how to block the DC offset of an AC signal — that just requires putting a capacitor in series, right? But what if the AC signal doesn’t alternate very often? In that case, things get a little more complicated.

Or at least that’s what [Limpkin] discovered, which led him to design this low-frequency DC block. Having found that commercially available DC blocks typically have a cutoff frequency of 100 kHz, which is far too high to measure power rail ripple in his low-noise amplifier, he hit the books in search of an appropriate design. What he came up with is a  non-polarized capacitor in series followed by a pair of PIN diodes shunted to ground. The diodes are in opposite polarities and serve to limit how much voltage passes out of the filter. The filter was designed for a cutoff frequency of 6.37 Hz, and [Limpkin]’s testing showed a 3-dB cutoff of 6.31 Hz — not bad. After some torture testing to make sure it wouldn’t blow up, he used it to measure the ripple on a bench power supply.

It’s a neat little circuit that ended up being a good learning experience, both for [Limpkin] and for us.

Scorched Moon: Secret Project A119

May 9, 2023 by 35 Comments

In today’s world, it is hard to realize how frightened Americans were at the news of Sputnik orbiting the Earth. Part of it was a fear of what a rival nation could do if they could fly over your country with impunity. Part of it was simply fear generated by propaganda. While America won the race to the moon, that wasn’t clear in the 1950s. The Soviet Union was ahead in the ability to deliver bombs using planes and missiles. They launched Sputnik on a modified ICBM, while American attempts to do the same failed spectacularly. The Air Force wanted ideas about how to respond to Sputnik, and one of the most disturbing ones was project A119, a project we were reminded of recently by a BBC post.

In all fairness, the Soviets had an almost identical plan, code-named E4. Fortunately, both sides eventually realized these plans weren’t a good idea. Oh, did we forget to mention that A119 and E4 were plans to detonate a nuclear device on the moon?

Continue reading “Scorched Moon: Secret Project A119” →

Tiny Orrery Keeps The Planets In Their Places

May 9, 2023 by 9 Comments

[Frans] claims to have made the world’s smallest wooden orrery. We won’t take a position on that — such things are best left up to the good folks at Guinness. But given that the whole thing is seriously in danger of being dwarfed by a USB-C connector, we’d say he’s got a pretty good shot at that record.

The key to keeping this planetarium so petite while making it largely out of wood is to eschew the complex gear trains that usually bring the Music of the Spheres to life in such devices. The layered base of the orrery, with pieces cut from a sheet of basswood using a laser cutter, contains a single tiny stepper motor and just two gears. A zodiac disc sits atop the base and is the only driven element in the orrery; every other celestial body moves thanks to a pin set into the zodiac disc. An ESP32 C3 contacts a NASA feed once a day to get the relative positions of the planets and uses the zodiac disk to arrange everything nicely for the day. The video below shows the “Planet Spinner” in action.

We love the look of this project; the burnt edges and lightly smoked surface of the laser-cut wooden parts look fantastic, and the contrast with the brass wires is striking. We’ve seen an orrery or two around here, executed in everything from solid brass to Lego, but this one really tickled our fancy. Continue reading “Tiny Orrery Keeps The Planets In Their Places” →