A Deep Dive Into The Coolness That Was CRT Projectors

October 11, 2025 by Donald Papp 19 Comments

CRT monitors: there’s nothing quite like ’em. But did you know that video projectors used to use CRTs? A trio of monochrome CRTs, in fact: one for each color; red, green, and blue. By their powers combined, these monsters were capable of fantastic resolution and image quality. Despite being nowhere near as bright as modern projectors, after being properly set up, [Technology Connections] says it’s still one of the best projected images he has seen outside of a movie theatre.

After a twenty-minute startup to reach thermal equilibrium, one can settle down with a chunky service manual for a ponderous calibration process involving an enormous remote control. The reward is a fantastic (albeit brightness-limited) picture.

Still, these projectors had drawbacks. They were limited in brightness, of course. But they were also complex, labor-intensive beasts to set up and calibrate. On the other hand, at least they were heavy.

[Technology Connections] gives us a good look at the Sony VPH-D50HT Mark II CRT Projector in its tri-lobed, liquid-cooled glory. This model is a relic by today’s standards, but natively supports 1080i via component video input and even preserves image quality and resolution by reshaping the image in each CRT to perform things like keystone correction, thus compensating for projection angle right at the source. Being an analog device, there is no hint of screen door effect or any other digital artifact. The picture is just there, limited only by the specks of phosphor on the face of each tube.

Converging and calibrating three separate projectors really was a nontrivial undertaking. There are some similarities to the big screen rear-projection TVs of the 90s and early 2000s (which were then displaced by plasma and flat-panel LCD displays). Unlike enclosed rear-projection TVs, the screen for projectors was not fixed, which meant all that calibration needed to be done on-site. A walkthrough of what that process was like — done with the help of many test patterns and a remote control that is as monstrous as it is confusing — starts at 15:35 in the video below.

Like rear-projection TVs, these projectors were displaced by newer technologies that were lighter, brighter, and easier to use. Still, just like other CRT displays, there was nothing quite like them. And if you find esoteric projector technologies intriguing, we have a feeling you will love the Eidophor.

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Entering The Wild World Of Power Over Ethernet

October 11, 2025 by Maya Posch 43 Comments

As Ethernet became the world-wide standard for wired networking, there was one nagging problem. You already have to plug in the network cable. But then you have to also plug in a power cable. That power cable needs to be long enough. And have the right plug on it for your country. And provide the right current and voltage. That’s how Power over Ethernet (PoE) was born, first in a veritable Wild West of proprietary standards and passive injectors, then in a standardized process. Recently [T. K. Hareendran] wrote a primer on PoE, with more of a DIY intro focus, including some favorite PoE PD (powered device) chips to use in your own design.

You can still totally use passive PoE if that’s your jam, and you have full control over the network and any connected devices. This would allow you to, for example, power your SBCs for a couple of bucks, although for adding PoE to your Mac Mini you may want to look at some more refined options, if only as a safety precaution.

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A Casio Toy Synth Is Ready To ROCK!

October 11, 2025 by Jenny List 4 Comments

There is likely to be more than one of you who has eyed up a child’s toy synthesizer in a second hand store, and considered making something more impressive with it. In many cases these instruments are underwhelming, having a very small subset of functions based into their black-epoxy-blob microcontrollers.

[Make Something] found a Casio toy synth that has a few more functions than the average model, and with the addition of some extra effects electronics and a beautifully made case, turned it into an altogether more interesting instrument.

Most of the video has an element of workshop porn about it, as he makes a very nice Moog-style console case for it, a task made easier by an impressive array of CNC tools. The electronics are slightly more interesting, being a selection of cheap guitar pedals gutted and combined with a cheap tube preamp board. The result is a machine capable of some far more interesting sounds

We think many Hackaday readers would be able to repeat these functions from scratch without the pedals, and while the case is a thing of beauty it’s likely a decent job could be done with a little less finesse on more commonplace tools. Perhaps it’s worth giving those toy synths a second look, because they really can be had for pennies if you look hard enough. Perhaps it’s an easier option than a previous toy musical upgrade.

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Easy For The Masses

October 11, 2025 by Elliot Williams 75 Comments

Last week, we were talking about how glad we are to be the type who by-and-large understands technology, and how it’s becoming more and more difficult to simply get along otherwise. We thought we had a good handle on the topic.

Then, we were talking about Google’s plans to require an ID for Android developers, and whether or not this will shut down free and open software development on the Android platform. Would this be the end of the ability to run whatever software that you’d like on your phone? Google offered the figleaf that “sideloading” – installing software through methods other than Google’s official store, would still be be allowed. But there’s a catch – you have to use Android Debug Bridge (ADB).

Is that a relief? It surely means that I will be able to install anything I want: I use ADB all the time, because it’s one of the fastest and easiest ways to transfer files and update software on the device. But how many non-techies do you know who use ADB? We’d guess that requiring this step shuts out 99.9% of Android users. If you make software hard to install for the masses, even if you make it possible for the geeks, you’re effectively killing it.

I have long wondered why end-to-end encrypted e-mail isn’t the default. After all, getting a GPG signing key, distributing it to your friends, and then reading mail with supporting software shouldn’t be a big deal, right? If GPG signing were available by default in Outlook or GMail, everyone would sign their e-mail. But there is no dead-simple, non-techie friendly way to do so, and so nobody does it.

Requiring ADB to load Android software is going to have the same effect, and it’s poised to severely restrict the amount of good, open software we have on the platform unless we can figure out a way to make installing that software easy enough that even the naive users can do it.

Toasty Subwoofer Limps Back To Life

October 11, 2025 by Al Williams 6 Comments

[JohnAudioTech] noticed there was no bass on the TV at his parents’ house. That led to the discovery of a blown fuse and a corresponding repair. When he opened it up, he could smell that something had gone on in the amplifier. You can follow the repair in the video below.

His first theory was that some glue became conductive and shorted the power rails. We were skeptical, to be honest. When he fed power to it through a current limiter, he could hear a sizzling noise and even see a little glowing from the hot component.

Disassembly ensued. Removing the suspect components showed some seriously burned components and some charring under a switching transistor. The capacitors looked much worse for wear, and the PCB needed some wires to jumper burned conductors.

At the end, there was thumping, so it seems the surgery was a success. However, testing blew a fuse again, which made us nervous. Still, seems to work if you don’t drive it too hard.

We always enjoy watching a teardown, and if there’s a repair too, that’s even better.

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The Electret Preamp You Might Need

October 11, 2025 by Jenny List 19 Comments

Electret capsules can be found in some of the highest quality microphones for studio use, as well as in some of the very cheapest microphone capsules on the market. More care and attention has gone into the high-end capsule and its associated circuitry than the cheap one, but is it still possible to get good quality from something costing under a dollar? [Mubarak Basha] thinks so, and has designed a preamp circuit to get the best from a cheap electret capsule.

These capsules may be cheap, but with the addition of a low voltage supply, a resistor, and a capacitor, their internal FET delivers a decent enough input to many a project. To improve on that will need a bit of effort, and in this the preamp delivers by taking care to match impedance, impose a carefully chosen frequency response, and just the right gain to derive a line level output from the electret’s level. It’s hardly a complex circuit, but that’s not always necessary.

As always in these situations, without appropriate test equipment it’s difficult to gauge quality. We’d say this though, if you make one of these and it falls short, you won’t have spent much. Meanwhile if you’re curious about electrets, here’s our guide.

Programming Space Game For X86 In Assembly Without An Operating System

October 10, 2025 by John Elliot V 40 Comments

In this video our hacker [Inkbox] shows us how to create a computer game that runs directly on computer hardware, without an operating system!

[Inkbox] briefly explains what BIOS is, then covers how UEFI replaces it. He talks about the genesis of UEFI from Intel in the late 90s. After Intel’s implementation of UEFI was made open source it got picked up by the TianoCore community who make tools such as the TianoCore EDK II.

[Inkbox] explains that the UEFI implementation provides boot services and runtime services. Boot services include things such as loading memory management facilities or running other UEFI applications, and runtime services include things like system clock access and system reset. In addition to these services there are many more UEFI protocols that are available.

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