Vision Impaired Electronics Engineer Shows The Way To Get Things Done

November 26, 2021 by Ryan Flowers 18 Comments

A funny thing happens as the average electronics hobbyist gets older: Their eyes- well they just don’t work the same as they used to. But what if your life started out with compromised vision? In this epic forum post (Google translated from Polish to English), we meet nearly blind hacker [Urgon]. He goes into great detail about his condition and how it affects not just his daily life, but also his abilities as an electronics engineer. Or conversely, how it doesn’t.

[Urgon]’s origin story is familiar. At eight years old, he disassembled his first television. His self-education continued by using his remaining vision to soak up every bit of literature about electronics that he could get his hands on. A well-intentioned but protective mother kept him away from soldering irons, fearing that the close proximity to his good eye might not bode well for his remaining vision.

If Urgon can solder 0805's, so can you! — If Urgon can solder SOIC’s 0805’s, so can you!

Despite a failed eye, and his other having quite severe glaucoma, [Urgon] has persevered. He uses assistive technologies as you’d expect, but notes that in more recent times some excellent free software has surpassed some of the commercial products he used in the past.

While even the sighted among us often shy away from SMD components, [Urgon] dives right in. SOIC packages and 0805 parts don’t hold him back. Bright LED flashlights, zooming in with his smart phone, and surely a healthy dose of patience make his hackery possible.

That’s not to say that [Urgon] hasn’t had some noteworthy incidents. He’s suffered electric shock from the 400 V capacitors in an ATX PSU, burned his face with his soldering iron, and even managed to step on a DIP package. Barefoot. Yes, the pins were facing up.

But wait- there’s more! In this follow-up post, [Urgon] discusses more assistive/adaptive technologies and how hackers like you and I can focus our efforts on things the vision impaired will find most helpful.

Our hats are off to [Urgon] and those like him who persevere despite the odds. We can all learn from [Urgon]’s hacker spirit and his dedication to the craft. We recently covered some blind software hackers who have taken it upon themselves to fly passenger jets– virtually, of course!

Thanks to [Moryc] for the excellent tip!

ESP32 Brings Air Purifier Online With Home Assistant

November 25, 2021 by Tom Nardi 7 Comments

A lot of hackers are rightfully concerned about the privacy issues that surround many of today’s “smart” gadgets, but it’s hard to argue that the ability to remotely control devices around your home isn’t convenient. Enter self-hosted, open source projects like Home Assistant. This provides the framework for building out a home automation system without having your ~~soul~~ information sold, but as you might expect, you’re going to have to put some effort in to get the most of it.

For example, take a look at this Phillips AC4014 air purifier that [Anton] connected to Home Assistant by way of an ESP32. Rather than getting too bogged down in reverse engineering the purifier’s surprisingly complex internal electronics, he took the easy way out and wired a couple of relays across the power and fan speed buttons; this allows the device to be easily controlled by the microcontroller, without impacting the functionality of the original controls.

But since those front panel controls still work, that meant [Anton] needed a way for the ESP32 to detect the device’s status and report that to Home Assistant so everything stayed in sync. So he looked around on the PCB for a trace that got powered up when the air purifier was up and running, which he connected to a pin of the microcontroller through a transistor. This let’s the firmware determine if the machine is running or not just by checking if the appropriate pin has gone high.

Speaking of the firmware, [Anton] decided to use ESPHome rather than trying to write his own code from scratch. This project allows you to rapidly add new devices to Home Assistant by providing the firmware with a relatively simple YAML configuration file, which he’s provided as an example. In fact, he’s provided quite a lot of examples with this project, down to an annotated image of the PCB that shows where to tap your wires into. He’s done quite a service for anyone who’s got this same model of air purifier.

This unit doesn’t appear to have any capability of actually checking the quality of the air in the room, but we’ve recently seen a low-cost IKEA product that can do exactly that. Even better, it can be easily modified to report its findings over the network using the ESP8266.

A PDP 11 By Any Other Name: Heathkit H11 Teardown And Repair

November 22, 2021 by Al Williams 30 Comments

[Lee Adamson] is no stranger to classic computers. He recently picked up a Heathkit H11A which, as you might remember, is actually a PDP-11 from DEC. Well, technically, it is an LSI-11 but still. Like a proper LSI-11, the computer uses the DEC QBus. Unlike a lot of computers of its day, the H11 didn’t have a lot of switches and lights, but it did have an amazing software library for its day.

[Lee] takes us through a tour of all the different cards inside the thing. It is amazing when you think of today’s laptop motherboards that pack way more into a much smaller space. He also had to fix the power supply.

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Microplastics Are Everywhere: Land, Sea And Air

November 16, 2021 by Lewin Day 65 Comments

Plastics took off in the 20th century, with the new class of materials finding all manner of applications that metal, wood and paper simply couldn’t deliver on. Every field from electronics to the packaging of food found that plastics could play a role.

Now, over 150 years since the development of Parkesine in 1867, we’re now realizing that plastics come with more than a few drawbacks. They don’t break down well in nature, and now microplastics are beginning to appear all over the Earth, even in places where humans rarely tread. It seems they may even spread via the air, so let’s take a look at this growing problem and what can be done about it.

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This is a MIDI harp that is played by waving your hands in the air over the infrared distance sensors.

Teensy MIDI Air Harp Sounds Huge

November 15, 2021 by Kristina Panos 4 Comments

Some of the coolest sounds come from wild instruments like orchestra strings, fretless basses, and theremins — instruments that aren’t tied down by the constraints of frets and other kinds of note boundaries. [XenonJohn]’s air harp is definitely among this class of music makers, all of which require a certain level of manual finesse to play well.

Although inspired by Jean-Michel Jarre’s laser harp, there are no lasers here. This is a MIDI aetherharp, aka an air harp, and it is played by interrupting the signals from a set of eight infrared distance sensors. These sensors can be played at three different heights for a total of 24 notes, plus there’s a little joystick for doing pitch bends.

Inside the wooden enclosure of this aetherharp is a Teensy 3.5 and eight infrared distance sensors with particularly long ranges. On top is a layer of red acrylic that doesn’t affect the playability, except in bright sunlight. Although you could use most any MIDI software to produce the actual sounds, [XenonJohn] chose VMPK (Virtual MIDI Piano Keyboard). Be sure to check it out in action after the break.

Not dangerous enough for you? Here’s a laser harp that involves a Tesla coil.

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Automated Air Cannon Shoots Smoke Rings

November 12, 2021 by Lewin Day 13 Comments

Air cannons are fun, and became a part of mainstream culture with the popular Airzooka toy. Of course, cocking and firing the Airzooka gets tiring after a while, and they’re kind of a little small. This build from [1alembic] delivers on both those counts.

The result is a bigger air cannon that repeatedly fires all by itself. The cannon itself is built out of a trash can with the bottom cut out. It’s then fitted with a diaphragm made out of a heavy-duty trash bag covered in duct tape for added strength. Latex hose is then installed inside the trash can, attached to the diaphragm. Thus, the diaphragm can be pulled back, and when released, it’s pulled forward, creating a rush of air through the trash can which generates a vortex ring just like the smaller Airzooka.

The automation of the cannon is beautifully simple. A string is attached to the back of the diaphragm, and wrapped around a rod so it can be wound up. This allows a wiper motor to turn the rod via a set of gears, pulling the diaphragm back.

However, the drive gear on the wiper motor has half its teeth missing. The system is then set up so that once the diaphragm is pulled right back, the drive gear gets to the missing teeth, allowing the winder rod to spin back freely as the diaphragm shoots forward, firing the air cannon. The cycle then repeats as the drive gear re-engages the winding mechanism.

Paired with a smoke machine, the air cannon will whirr away, firing beautiful smoke rings at regular intervals until it’s switched off. It’s an elegant thing that we’d love to leave set up at a party to add some atmosphere. We’ve seen other air cannons built with some real fire-power, too. Video after the break.

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Heathkit IM-13 VTVM Repair

November 7, 2021 by Al Williams 16 Comments

If you are under a certain age, you might not know the initialism VTVM. It stands for vacuum tube voltmeter. At first glance, you might just think that was shorthand for “old voltmeter” but, in fact, a VTVM filled a vital role in the old days of measuring instruments. [The Radio Mechanic] takes us inside a Heathkit IM-13 that needed some loving, and for its day it was an impressive little instrument.

Today, our meters almost always have a FET front end and probably uses a MOSFET. That means the voltage measurement probes don’t really connect to the meter at all. In a properly working MOSFET, the DC resistance between the gate and the rest of the circuit is practically infinite. It is more likely that a very large resistor (like 10 megaohms) is setting the input impedance because the gate by itself could pick up electrostatic voltage that might destroy the device. A high resistance like that is great when you make measurements because it is very unlikely to disturb the circuit you are trying to measure and it leads to more accurate measurements.

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