If you’ve ever wanted to watch someone bring CP/M up on a new system and you have a couple of hours to spare, check out the recorded live stream of [Poking Technology]. The system in question is an Agon Light, a modern board with a Z-80-derived CPU. If you want to get right to the porting part, you might want to skip about 31 minutes of the nearly 2.5-hour video.
The first half hour is more about the built-in assembler and the board in general. If you’ve ever ported CP/M before, you know it isn’t as hard as bootstrapping a modern operating system. There are two major things you need: A BIOS, which is specific to your machine, and a BDOS, which is usually taken verbatim from the operating system sources. Your programs typically call one of the 40 or so functions in the BDOS.
Snail mail. You may not think much of it these days, but the mail doesn’t stop and it never has. Every type of mail from postcards and letters to large envelopes and packages of all sizes moves every single day all over the US, even though it isn’t typically delivered on Sundays. Dealing with the ever-increasing volume of physical mail has called for the invention and evolution of automatic mail sorting machines that are used by both postal facilities and businesses alike.
While mail sorting machines have grown and matured over the years, the human element of the task remains intact. As long as people type addresses, write them by hand, and/or print them in handwriting fonts by the hundreds, there will need to be humans on hand to verify at least a few of them that are really hard to read.
There are roughly a dozen different types of mail sorting machines in 2023. In this series, we’re going to take a look at most of them, along with many other aspects of the United States Postal Service and its history.
One of the Linux stories of the moment has come from Red Hat, with their ongoing efforts to make accessing the source of their Red Hat Enterprise Linux product a paid-for only process. This has caused consternation and annoyance alike, from the open source community angry at any liberties taken with the GPL, and from the community of RHEL users and customers concerned as to what it might mean for them.
This is good news for all who use Red Hat derived software and we expect the likes of Rocky Linux will be taking a close look at it, but it’s also a canny move from the European company as they no doubt hope to tempt away some of those commercial Red Hat customers with a promise of stability and their existing experience supporting Red Hat users through their mixed Linux support packages. We hope they’ll continue to maintain their relationship with the open source world, and that the prospect of their actions unleashing a new commercial challenge causes Red Hat to move away from the brink a little.
If you’ve been building circuits for any length of time, you probably know you need decoupling capacitors to keep your circuits stable. But even though it’s a favorite technique of ours, just scattering some around your PCB and hoping for the best isn’t necessarily the best approach. If you want to dig deeper into the why and how of decoupling, check out [Stephen Fleeman’s] post on the topic.
It is easy to think of capacitors as open circuits at DC and short circuits at high frequencies, shunting noise to ground. But the truth is more complex than that. Stray resistance and inductance mean that your simple decoupling capacitor will have a resonant frequency. This limits the high frequency protection so you often see multiple values used in parallel to respond to different frequencies.
Because the stray resistance and inductance plays a part, you may want to use fatter traces — less resistance — and shorter runs for less inductance. Of course, you can also use power and ground planes on the PCB as a form of decoupling. At the end of the post, [Stephen] talks a little about the importance of digital and analog ground that interact in a specific way.
If you want to do some empirical testing, you can build a test rig and do the work. Or check with [Bil Herd] about PCB inductance.
Having a chemistry lab fully stocked with all necessary equipment is the dream of students, teachers, and professors alike, but a lot of that equipment can be prohibitively expensive. Even in universities, labs are often left using old or worn-out equipment due to cost. So one could imagine that in high schools this is even a more pronounced problem. High school student [Aidan Miller] has solved this problem with at least one piece of lab equipment, bringing the cost for a centrifuge down to around $10 USD.
Part of the savings is due to the fact that [Aidan] has put together a smaller sized centrifuge, known as a micro-centrifuge. The function is still the same though, spinning samples to separate them out the constituents by weight. The 3D printed base of the centrifuge houses a switch and 9 V battery and also holds a small motor which spins the rotor. The rotor itself is also 3D printed, and needed to be a very specific shape to ensure that it could hold the samples properly at high RPM and maintain reasonable balance while spinning.
As a project it’s fairly simple and straightforward to build, but the more impressive thing here is how much it brings down the cost of lab equipment especially for high school labs that might otherwise struggle for funding. Of course it requires the use of a 3D printer but the costs of those have been coming down significantly as well, especially for things like this portable 3D printer which was also built by a high school student.
Whenever phone-based thermal cameras are brought up here on Hackaday, we inevitably receive some comments about how they’re a bad investment compared to a standalone unit. Sure they might be cheaper, but what happens in a couple years when the app stops working and the manufacturer no longer feels like keeping it updated?
It’s a valid concern, and if we’re honest, we don’t like the idea of relying on some shady proprietary app just to use the camera in the first place. Which is why we’re so excited to see open source software being developed that allows you to use these (relatively) inexpensive cameras on your computer. [Les Wright] recently sent word that he’s been working on a project called PyThermalCamera which specifically targets the TOPDON TC001, which in turn is based on a project called P2Pro-Viewer developed by LeoDJ for the InfiRay P2 Pro.
Readers may recall we posted a review of the P2 Pro last month, and while the compact hardware was very impressive, the official Android software lacked a certain degree of polish. While these projects won’t help you on the mobile front in their current form, it’s good to know there’s at least a viable “Plan B” if you’re unwilling or unable to use the software provided from the manufacturer. Naturally this also opens up a lot of new possibilities for the camera, as being connected to a proper Linux box means you can do all sorts of interesting things with the video feed.
The two video feeds on the left are combined to produce the final thermal image.
Speaking of the video feed, we should say that both of these projects were born out of a reverse engineering effort by members of the EEVblog forums. They figured out early on that the InfiRay (and other similar models) were picked up as a standard USB video device by Linux, and that they provided two video streams: one being a B&W feed from the camera where the relative temperature is used as luminance, and the other containing the raw thermal data cleverly encoded into a green-tinted video. With a little poking they found an FFmpeg one liner that would combine the two streams, which provided the basis for much of the future work.
In the video below, you can see the review [Les] produced for the TOPDON TC001, which includes a demonstration of both the official Windows software and his homebrew alternative running on the Raspberry Pi. Here’s hoping these projects inspire others to join in the effort to produce flexible open source tools that not only unlock the impressive capabilities of these new thermal cameras but save us from having to install yet another smartphone application just to use a device we purchased.
[OZ2CPU] has an HP power supply that is about 30 years old. It looks brand new, though, and has three outputs and includes tracking for the adjustable positive and negative supply. After a quick demo of the unit’s features, he tears it all down so we can see inside. You can catch the video below.
Some similar supplies offer a 10-turn adjustment knob, but this one doesn’t. Inside is a beefy transformer and quite a few through-hole components. There was room to change the main adjusted pot to a 10-turn unit, so he made the mod.
