Author: Bryan Cockfield

1761 Articles

Re-imagining The Water Supply

October 15, 2023 by 48 Comments

Getting freshwater supplied across cities and towns in a reliable and safe way is no simple task. Not only is a natural freshwater reservoir or other supply needed, but making sure the water is safe to drink and then shipping it out over a dense network of pumps and pipes can cost a surprising amount of time and money. It also hinges on a reliable power grid, which is something Texas resident [Suburban Biology] doesn’t have. But since fresh water literally falls out of the sky for free, he decided to take this matter into his own hands.

The main strategy with a system like this is to keep the rainwater as clean as possible before storage so that expensive treatment systems are less necessary. That means no asphalt shingles, a way to divert the first bit of rain that washes dust and other contaminants off the roof away, and a safe tank. This install uses a 30,000 gallon tank placed above ground for storage, but that’s not the only thing that goes into a big rainwater catchment system like this. A system of PVC pipes are needed both for sending rainwater from the roofs of the buildings into the tank and for pumping it into the home for use. With all of that in place it’s both a hedge against climate change, unstable electric grids, and even separates the user from the local aquifer which may or may not have its own major issues depending on where you live.

While Texas legally protects the rights of citizens to collect and store rainwater, the same isn’t true for all areas. For example, Colorado only just passed a law allowing the collection and storage of a meager 110 gallons of rainwater and forbade it entirely beforehand. There are some other considerations for a project like this too, largely that above-ground systems generally won’t work in cold climates. On the other hand, large systems like these are really only needed where rainfall is infrequent; in more tropical areas like south Florida a much smaller storage system can be used

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Hackaday Prize 2023: AC Measurements Made Easy

October 12, 2023 by 17 Comments

When working on simple DC systems, a small low-cost multimeter from the hardware store will get the job done well enough. Often they have the capability for measuring AC, but this is where cheap meters can get tripped up. Unless the waveform is a perfect sinusoid at a specific frequency, their simple algorithms won’t be able to give accurate readings like a high-quality meter will. [hesam.moshiri] took this as a design challenge, though, and built an AC multimeter to take into account some of the edge cases that come up when working with AC circuits, especially when dealing with inductive loads.

The small meter, an upgrade from a previous Arduino version that is now based on the ESP32, is capable of assessing root mean square (RMS) voltage, RMS current, active power, power factor, and energy consumption after first being calibrated using the included push buttons. Readings are given via a small OLED screen and have an accuracy rate of 0.5% or better. The board also includes modern design considerations such as galvanic isolation between the measurement side of the meter and the user interface side, each with its own isolated power supply.  The schematics and bill-of-materials are also available for anyone looking to recreate or build on this design.

With the project built on an easily-accessible platform like the ESP32, it would be possible to use this as a base to measure other types of signals as well. Square and triangle waves, as well as signals with a large amount of harmonics or with varying frequencies, all need different measurement techniques in order to get accurate readings. Take a look at this classic multimeter to see what that entails.

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Error-Correcting RAM On The Desktop

October 12, 2023 by 55 Comments

When running a server, especially one with mission-critical applications, it’s common practice to use error-correcting code (ECC) memory. As the name suggests, it uses an error-correcting algorithm to continually check for and fix certain errors in memory. We don’t often see these memory modules on the desktop for plenty of reasons, among which are increased cost and overhead and decreased performance for only marginal gains, but if your data is of upmost importance even when working on a desktop machine, it is possible to get these modules up and running in certain modern AMD computers.

Specifically, this feature was available on AMD Ryzen CPUs, but since the 7000 series with the AM5 socket launched, the feature wasn’t officially supported anymore. [Rain] decided to upgrade their computer anyway, but there were some rumors floating around the Internet that this feature might still be functional. An upgrade to the new motherboard’s UEFI was required, as well as some tweaks to the Linux kernel to make sure there was support for these memory modules. After probing the system’s behavior, it is verified that the ECC RAM is working and properly reporting errors to the operating system.

Reporting to the OS and enabling the correct modules is one thing, actually correcting an error was another. It turns out that introducing errors manually and letting the memory correct them is possible as well, and [Rain] was able to perform this check during this process as well. While ECC RAM may be considered overkill for most desktop users, it offers valuable data integrity for professional or work-related tasks. Just don’t use it for your Super Mario 64 speedruns.

Antennas Can Be A Total Mystery

October 10, 2023 by 14 Comments

The real action in the world of ham radio is generally in the high frequency bands. Despite the name, these are relatively low-frequency bands by modern standards and the antenna sizes can get a little extreme. After all, not everyone can put up an 80-meter dipole, but ham radio operators have come up with a number of interesting ways of getting on the air anyway. The only problem is that a lot of these antennas don’t seem as though they should work half as well as they do, and [MIKROWAVE1] takes a look back on some of the more exotic radiators.

He does note that for a new ham radio operator it’s best to keep it simple, beginning work with a dipole, but there are still a number of options to keep the size down. A few examples are given using helically-wound vertical antennas or antennas with tuned sections of coaxial cable. From there the more esoteric antennas are explored, such as underground antennas, complex loops and other ways of making a long wire fit in a small space, and even simpler designs like throwing a weight with a piece of wire attached out the window of an apartment building.

While antenna theory is certainly a good start for building antennas, a lot of the design of antennas strays into artistry and even folklore as various hams will have successes with certain types and others won’t. It’s not a one-size-fits-all situation so the important thing is to keep experimenting and try anything that comes to mind as long as it helps get on the air. A good starting point is [Dan Maloney]’s $50 Ham Guide series, and one piece specifically dealing with HF antennas.

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CPU Built From Discrete Transistors

September 30, 2023 by 31 Comments

We all know, at least intellectually, that our computers are all built with lots of tiny transistors. But beyond that it’s a little hard to describe. They’re printed on a silicon wafer somehow, and since any sufficiently advanced technology is indistinguishable from magic, they miraculously create a large part of modern society. Even most computers from 40 or 50 years ago were built around various inscrutable integrated circuits. On the other hand, this computer goes all the way back to first principles and implements a complete processor out of individual transistors instead.

The transistor computer uses over 2000 individual transistors to implement everything comprising the 11-bit CPU. The creator, Reddit user [ Weekly_Salamander_78] also has an online interactive book that walks through each of the steps that is required to get to the point of having a working computer like this. Starting with a guide on building logic gates from transistors it will eventually cover the arithmetic logic unit, adders, memory, clocks, and everything else that is needed for the complete CPU to get up and running. The design does rely on an Arduino for memory to simplify some things, and in the end it’s able to run a Hello, World! program and play a simple dinosaur game as well.

Building a computer out of discrete components like this is an impressive accomplishment, although we might not envy the creator of it when it comes time for troubleshooting or maintenance of all of those individual components. Presumably it would be much easier to work on than something like a relay computer, but for now we’ll all take a moment to be thankful that almost no one needs to work on debugging vacuum tube computers anymore.

FedEx Robot Solves Complex Packing Problems

September 29, 2023 by 44 Comments

Despite the fact that it constantly seems like we’re in the midst of a robotics- and artificial intelligence-driven revolution, there are a number of tasks that continue to elude even the best machine learning algorithms and robots. The clothing industry is an excellent example, where the flimsy materials can easily trip up robotic manipulators. But one task like this that seems like it might soon be solve is packing cargo into trucks, as FedEx is trying to do with one of their new robots.

Part of the reason this task is so difficult is that packing problems, similar to “traveling salesman” problems, are surprisingly complex. The packages are not presented to the robot in any particular order, and need to be efficiently placed according to weight and size. This robot, called DexR, uses artificial intelligence paired with an array of sensors to get an idea of each package’s dimensions, which allows it to then plan stacking and ordering configurations and ensure secure fits between all of the other packages. The robot must also be capable of quickly adapting if any packages shift during stacking and re-order or re-stack them.

As robotics platforms and artificial intelligence continue to improve, it’s likely we’ll see a flurry of complex problems like these solved by machine instead of by human. Tackling real-world tasks are often more complex than they seem, as anyone with a printer an a PC LOAD LETTER error can attest to, even handling single sheets of paper can be a difficult task for a robot. Interfacing with these types of robots can be a walk in the park, though, provided you read the documentation first.

Power Supplies Without Transformers

September 29, 2023 by 71 Comments

For one-off projects or prototyping, it’s not too hard to find a wall wart or power supply to send a few joules of energy from the wall outlet to your circuit. Most of these power supplies use a transformer to step down the voltage to a more usable level and also to provide some galvanic isolation to the low voltage circuit. But for circuits where weight, volume, or cost are a major concern, a transformer may be omitted in the circuit design in favor of some sort of transformerless power supply.

While power supplies with this design do have many advantages, some care needs to be taken with regard to safety. The guide outlines four designs of increasing complexity which first puts out a basic transformerless power supply, using a series capacitor to limit current. To bring the voltage to an acceptable level, a recognizable bridge rectifier is paired with a capacitor as well as a zener diode. The second circuit presented adds voltage stabilization using a transistor and 78XX regulator. From there, zero-crossing detection is added to limit inrush surge currents, and the final design uses the venerable 555 timer to build a switching power supply.

Although it is noted several times throughout the guide, we’ll still point out here that transformerless designs like these introduce several safety issues since a mistake or fault can lead to the circuit being exposed to the mains voltage. However, with proper care and design it’s possible to make use of these designs to build more effective power supplies that can be safe to use for powering whatever circuit might energy but might not require the cost or weight of a transformer. For more on the theory of these interesting circuits and a few examples of where they are often found, check out the shocking truth about transformerless power supplies.

Thanks to [Stephen] for the tip!