Hacking Transmitters, 1920s Style

November 28, 2019 by 9 Comments

The origin of the term “breadboard” comes from an amusing past when wooden bread boards were swiped from kitchens and used as a canvas for radio hobbyists to roll homemade capacitors, inductors, and switches. At a period when commercial electronic components were limited, anything within reach was fair game.

[Andy Flowers], call sign K0SM, recently recreated some early transmitters using the same resources and techniques from the 1920s for the Bruce Kelley 1929 QSO Party. The style of the transmitters are based on [Ralph Hartley]’s oscillator circuit built for Bell Telephone in 1915. Most of the components he uses are from the time period, and one of the tubes he uses is even one of four tubes from the first Transatlantic contact in 1923.

Apart from vacuum tubes (which could be purchased) and meters (which could be scrounged from automobiles) [Flowers] recreated his own ferrite plate and outlet condensers for tuning the antennas. The spiderweb coils may not be as common today, but can be found in older Crosley receivers and use less wire than comparable cylindrical coils.

A number of others features of the transmitters also evoke period nostalgia. The coupling to the antenna can be changed using movable glass rods, although without shielding there are quite a number of factors to account for. A vertical panel in the 1920s style also shows measurements from the filament, plate current, and antenna coupling.

While amature radio has become increasingly high-tech over the last few years, it’s always good to see dedicated individuals keeping the old ways alive; no matter what kind of technology they’re interested in.

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Vertical Train Hauls Up The Wall

November 28, 2019 by 19 Comments

Trains are great for hauling massive amounts of cargo from point A to point B, and occasionally, point C on weekends. But they’re not really known for climbing hills well, and anything vertical is right out. Regardless, [Can Altineller] knows what he wants and set to work, creating the 3D Printed Wall Train.

The first step was to get the train to stick to a vertical surface. This was achieved with the use of neodymium magnets in the train, which are attracted to laser-cut steel plates beneath the plastic tracks. The train itself consists of a custom 3D printed locomotive, outfitted with a motor and step-down gears that drive all four wheels. Said wheels are of a conical shape, and covered with rubber to provide enough grip to overcome gravity. The project is a progression from [Cal]’s earlier four-motor build.

The final result is a charming wall display, with the four-wheel drive train merrily tugging its carriages around the circular course ad infinitum. It’s a fun build, and we’d love to see similar techniques applied to a bigger layout. If this whets your appetite for model railroading, consider building your own turntable, or implementing some fancy sensors. Video after the break.

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Iron Man Puts Yet Another Hacker Up In Arms

November 28, 2019 by 9 Comments

When Iron Man movie came out, we’d bet there wasn’t a single hacker that left the theater without daydreaming about having a few robotic lab assistants of their own. But unlike most of them, [Tony-Lin] decided to turn his celluloid dreams into a reality and started work on his robotic arm, Abot.

Abot is built from a combination of 5 mm nylon panels and 3D printed parts. One thing we found particularly interesting about this build is that the motor reductions for the joints are done using stages of pulleys and GT2 belting rather than planetary gear boxes or cycloidal drives. This produces a lightweight and affordable build.

He also designed his own driver boards for each motor using the STM32. They communicate with a CAN bus which uses USB connectors, an interesting choice. Just make sure not to try and charge your phone with it.

We have to admit to a little jealousy that [Tony] is moved himself a bit closer to being Tony Stark than the rest of us are likely to get. We’ll just have to live vicariously through the documentation of his project.

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A Division In Voltage Standards

November 28, 2019 by 152 Comments

During my recent trip to Europe, I found out that converters were not as commonly sold as adapters, and for a good reason. The majority of the world receives 220-240 V single phase voltage at 50-60 Hz with the surprisingly small number of exceptions being Canada, Colombia, Japan, Taiwan, the United States, Venezuela, and several other nations in the Caribbean and Central America.

While the majority of countries have one defined plug type, several countries in Latin America, Africa, and Asia use a collection of incompatible plugs for different wall outlets, which requires a number of adapters depending on the region traveled.

Although there is a fair degree of standardization among most countries with regards to the voltage used for domestic appliances, what has caused the rift between the 220-240 V standard and the 100-127 V standards used in the remaining nations?

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Raspberry Pi 4 HDMI Is Jamming Its Own WiFi

November 28, 2019 by 87 Comments

Making upgrades to a popular product line might sound like a good idea, but adding bigger/better/faster parts to an existing product can cause unforeseen problems. For example, dropping a more powerful engine in an existing car platform might seem to work at first until people start reporting that the increased torque is bending the frame. In the Raspberry Pi world, it seems that the “upgraded engine” in the Pi 4 is causing the WiFi to stop working under specific circumstances.

[Enrico Zini] noticed this issue and attempted to reproduce exactly what was causing the WiFi to drop out, and after testing various Pi 4 boards, power supplies, operating system version, and a plethora of other variables, the cause was isolated to the screen resolution. Apparently at the 2560×1440 setting using HDMI, the WiFi drops out. While you could think that an SoC might not be able to handle a high resolution, WiFi, and everything else this tiny computer has to do at once. But the actual cause seems to be a little more interesting than a simple system resources issue.

[Mike Walters] on a Twitter post about this issue probed around with a HackRF and discovered a radio frequency issue. It turns out that at this screen resolution, the Pi 4 emits some RF noise which is exactly in the range of WiFi channel 1. It seems that the Pi 4 is acting as a WiFi jammer on itself.

This story is pretty new, so hopefully the Raspberry Pi Foundation is aware of the issue and working on a correction. For now, though, it might be best to run a slightly lower resolution if you’re encountering this problem.

A Python Serial Terminal To Get You Out Of A Jam

November 28, 2019 by 21 Comments

When fiddling around with old computers, you can occasionally find yourself in a sticky situation. What may be a simple task with today’s hardware and software can be nearly impossible given the limited resources available to machines with 20 or 30 years on the clock. That’s where [bison] recently found himself when he needed to configure a device over serial, but didn’t have any way of installing the appropriate terminal emulator on his Fujitsu Lifebook C34S.

His solution, since he had Python 2.6 installed on the Debian 6 machine, was to write his own minimal serial terminal emulator. He intended for the code to be as terse as possible so it could be quickly typed in, should anyone else ever find themselves in need of talking to a serial device on Linux but can’t get screen or minicom installed.

The code is very simple, and even if you never find yourself needing to fire up an impromptu terminal, it offers an interesting example of how straightforward serial communications really are. The code opens up the /dev/ttyS0 device for reading, and after appending the appropriate return character, pushes the user’s keyboard input into it. Keep looping around, and you’ve got yourself an interactive terminal.

With this program written, [bison] was able to connect the 266 MHz C34S to his Retro WiFi SI, a modem adapter that bridges the gap between a vintage computer and modern wireless network. Gadgets like these allow you to browse BBSes as the creator intended, and can be fashioned with nothing more exotic than an ESP8266 running some open source code.

Add LEDs To Your Stained Glass

November 28, 2019 by 19 Comments

Stained glass is an art form that goes back many centuries, with the churches and cathedrals of Europe boasting many stunning examples from the mediaeval masters of the craft. You do not however have to go to York or Chartres cathedrals to experience stained glass, for it remains a vibrant and creative discipline with many contemporary practitioners. One thing the stained glass of today has in common with that of yesteryear though is that it remains static, being composed of pieces of glass held together by metal strips. This is something that [Frank Zhao] has addressed as he has evolved a technique that allows him to incorporate LEDs into static stained glass, making for a particularly eye-catching effect.

It’s likely that we join many readers in not knowing the intricacies of making a piece of stained glass, so his is a fascinating write-up for its step-by-step run-through. His stained glass cat has pieces of glass edged with copper tape, which he then solders together. Driving the LEDs is not something that should be alien to us, but his method of using the copper-and-solder stained glass joints as conductors for them by creating strategically placed cuts is very effective. The final effect is of a homogeneous piece without the cuts being particularly visible , but with a pleasing array of lights on the cat’s tail. Those of us for whom stained glass production is new have learned something of the technique, and stained glass artists have seen their craft do something completely new.

Stained glass hasn’t featured here too often, the closest we’ve come is this striking fake stained glass Iron-Man themed panel a few years ago.