Author: Bryan Cockfield

1760 Articles

Turning Down The Noise On SMPS

March 17, 2025 by 13 Comments

On paper, electricity behaves in easy-to-understand, predictable ways. That’s mostly because the wires on the page have zero resistance and the switching times are actually zero, whereas in real life neither of these things are true. That’s what makes things like switch-mode power supplies (SMPS) difficult to build and troubleshoot. Switching inductors and capacitors tens or hundreds of thousands of times a second (or more) causes some these difficulties to arise when these devices are built in the real world. [FesZ Electronis] takes a deep dive into some of the reasons these difficulties come up in this video.

The first piece of electronics that can generate noise in an SMPS are the rectifier diodes. These have a certain amount of non-ideal capacitance as well as which causes a phenomenon called reverse current, but this can be managed by proper component choice to somewhat to limit noise.

The other major piece of silicon in power supplies like this that drives noise are the switching transistors. Since the noise is generally caused by the switching itself, there is a lot that can be done here to help limit it. One thing is to slow down the amount of time it takes to transition between states, limiting the transients that form as a result of making and breaking connections rapidly. The other, similar to selecting diodes, is to select transistors that have properties (specifically relating to inherent capacitances) that will limit noise generation in applications like this.

Of course there is a lot more information as well as charts and graphs in [FesZ]’s video. He’s become well-known for deep dives into practical electrical engineering topics like these for a while now. We especially like his videos about impedance matching as well as a more recent video where he models a photovoltaic solar panel in SPICE.

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Tracking Deep-Sky Objects

March 13, 2025 by 2 Comments

Astrophotography, and astronomy in general, takes some fairly specialized tools and a high amount of precision. Setting up the equipment can also take a lot of time, especially for amateurs traveling to various locations with their equipment, so anything that can reduce the amount of time spent looking for objects and increasing the amount of time looking at them is a welcome addition, especially since nights where conditions are ideal for these activities can be rare. [Anton] developed this real-time tracking tool for deep sky objects (DSOs) to keep tabs on most of the interesting things out there a telescope can be pointed at.

[Anton] calls his tool the Nova DSO Altitude Tracker and gets its information from SIMBAD, updating every minute for a given location on the planet. With that location data, the program calculates altitude and azimuth for various objects and also helps the user keep track of other important variables like moon illumination and angle above the horizon. It also allows the user to highlight specific objects of interest, making sure they are front and center throughout the session. Each DSO can be selected from a list to display detailed information about it such as its path, time visible in the sky, and other properties.

To get the program running, essentially all that’s required is a computer capable of running Python and a display of some sort. From there it provides a quick view of the best objects to point one’s telescope or camera at without any guesswork. With all of the code available it shouldn’t be too much of a leap to do other things with the underlying software, either, such as tying it into a tracker of some sort like this DIY telescope tracking device we featured a while back.

Meshtastic Adds Wireless Connectivity To Possum Trap

March 12, 2025 by 10 Comments

Perhaps every gardener to attempt to grow a tomato, lettuce, or bean has had to contend with animals trying to enjoy the food before the gardener themselves can, whether it’s a groundhog, rabbit, mouse, crow, or even iguana. There are numerous ways to discourage these mischievous animals from foraging the garden beds including traps, but these devices have their downsides as well. False alarms can be a problem as well as trapping animals that will be overly aggravated to be inside the trap (like skunks) and while the latter problem can’t easily be solved by technology, the former can with the help of Meshtastic.

[Norman Jester]’s problem was an errant possum, but these nocturnal animals generally come out while humans are asleep, and other nighttime animals like rats can activate the trap and then escape. To help with this, a Meshtastic node was added to the San Diego mesh using a 3.5mm audio jack as a detector. When the trap is activated, the closing door yanks a plug out of the jack, alerting the node that the trap has been closed. If it’s a false alarm the trap can be easily and quickly reset, and if a possum has found its way in then it can be transported to a more suitable home the next day.

It’s worth noting that American possums (distinct from the Australian animals of the same name) are an often-misunderstood animal that generally do more good than harm. They help to control Lyme disease, eat a lot of waste that other animals won’t, don’t spread rabies, and don’t cause nearly as much disruption to human life as other animals like feral cats or raccoons. But if one is upsetting a garden or another type of animal is causing a disturbance, this Meshtastic solution does help solve some of the problems with live traps. For smaller animals, though, take a look at this Arudino-powered trap instead.

Thanks to [Dadsrcworkbench] for the tip!

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EPROM-based Enigma Machine

March 12, 2025 by 5 Comments

The Enigma machine is perhaps one of the most legendary devices to come out of World War II. The Germans used the ingenious cryptographic device to hide their communications from the Allies, who in turn spent an incredible amount of time and energy in finding a way to break it. While the original Enigma was a complicated electromechanical contraption, [DrMattRegan] recently set out to show how its operation can be replicated with an EPROM.

The German Enigma machine was, for the time, an extremely robust way of coding messages. Earlier versions proved somewhat easy to crack, but subsequent machines added more and more complexity rendering them almost impenetrable. The basis of the system was a set of rotors which encrypted each typed letter to a different one based on the settings and then advanced one place in their rotation, ensuring each letter was encrypted differently than the last. Essentially this is a finite-state machine, something perfectly suited for an EPROM. With all of the possible combinations programmed in advance, an initial rotor setting can be inputted, and then each key press is sent through the Enigma emulator which encrypts the letter, virtually advances the rotors, and then moves to the next letter with each clock cycle.

[DrMattRegan]’s video, also linked below, goes into much more historical and technical detail on how these machines worked, as well as some background on the British bombe, an electromechanical device used for decoding encrypted German messages. The first programmable, electronic, digital computer called Colossus was also developed to break encrypted Enigma messages as well, demonstrating yet another technology that came to the forefront during WWII.

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Solar-Powered E-Reader With No Buttons

March 10, 2025 by 21 Comments

Modern e-readers such as the Amazon Kindle are incredible pieces of engineering, but that doesn’t mean there’s no room for improvement. A device custom-built to your own specifications is always going to provide a more satisfying experience than something purchased off the shelf. That’s why [fel88] put together this custom e-reader which offers a number of unique features, such as a solar panel on the back and button-free operation.

One issue with modern e-readers, at least as [fel88] sees it, is that they have a lot of unnecessary features. This project removes most of them, stripping down the device to its core functionality: a straightforward menu for selecting books and gesture-sensing for navigating the menu as well as changing the pages. The only physical input on the device is a small reed switch to turn the device on. A 3D printed case holds the e-ink display and encloses the inner workings, driven by an Arduino Mega 2560 and powered by three lithium-ion capacitors (LICs) and a small solar panel.

By dropping all of the unnecessary features, the device doesn’t need to waste energy with things like WiFi or Bluetooth and can get around 880 pages on a single charge, not counting any extra energy coming in through the solar panel while it’s operating. The LICs will also theoretically improve its life cycle as well. If you’re still stuck with a paperweight when you formerly had a working e-reader, though, there are plenty of ways to bring old devices back to life as well.

Inexpensive Repairable Laptops, With Apple Style

March 10, 2025 by 41 Comments

Despite a general lack of real-world experience, many teenagers are overly confident in their opinions, often to the point of brashness and arrogance. In the late 90s and early 00s I was no different, firmly entrenched in a clichéd belief that Apple computers weren’t worth the silicon they were etched onto—even though I’d never actually used one. Eventually, thanks to a very good friend in college, a bit of Linux knowledge, and Apple’s switch to Intel processors, I finally abandoned this one irrational belief. Now, I maintain an array of Apple laptops for my own personal use that are not only surprisingly repairable and hacker-friendly but also serve as excellent, inexpensive Linux machines.

Of course, I will have ruffled a few feathers suggesting Apple laptops are repairable and inexpensive. This is certainly not true of their phones or their newer computers, but there was a time before 2016 when Apple built some impressively high quality, robust laptops that use standard parts, have removable batteries, and, thanks to Apple dropping support for these older machines in their latest operating systems, can also be found for sale for next to nothing. In a way that’s similar to buying a luxury car that’s only a few years old and letting someone else eat the bulk of the depreciation, a high quality laptop from this era is only one Linux install away from being a usable and relatively powerful machine at an excellent bargain. Continue reading “Inexpensive Repairable Laptops, With Apple Style” →

Copying Commodore Data Tapes, 40 Years Late

February 28, 2025 by 41 Comments

Unless you handle the backups for a large corporation, bank, or government entity, you likely haven’t stored much data to tape recently. But magnetic storage used to be fairly mainstream back in the 1980s for all kinds of computer programs. Plenty of computers used standard cassette tapes for this too but you couldn’t just copy them with standard audio equipment. You’d need something like this 1560 datasette from [Jan].

The core problem with using Hi-Fi equipment to copy tapes storing data instead of audio is that data tapes need to be much more precise in order to avoid losses that might not be noticeable in an audio recording. In the 80s computer companies like Commodore built tape drives specifically for their computers, so [Jan]’s project uses two of these 1530 drives to build this “1560” datasette. (No working 1530 hardware was harmed in this build.) An inverter circuit in one tape deck is used to provide the signal to write the data to the other tape, reliably copying data from these data tapes in a way Hi-Fi never could.

[Jan] does lament not having something like this back in the 80s when the Commodore was in its heyday, but there’s still a dedicated retrocomputing scene for these machines that will get plenty of use out of projects like this. If you need to go the other direction in time, there are also interfaces that allow data tapes from old Commodores to be read by modern computers with USB.

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