For as big, bulky, and power-hungry as they were, CRTs were an analog joy of the early days of TV, video games, and computers. The crackling high-voltage, the occasional whiff of ozone, the whizzing electrons lancing through a vacuum to excite a phosphorescent image — by comparison, thin-film LCDs are sterile and boring.
Sadly, CRTs are getting harder to come by these days, and at the extreme ends of the size spectrum, may never have been available at all. Thankfully, if your project demands a retro CRT look, fitting your LCD with a custom lens might just do the trick. The link leads to the first article in a series by [jamhamster] on the travails of lensmaking, which even when not practiced for precision lens production can still be tricky. After going through the basics of material selection — acrylic, but not cold-formed, please; such sheets have internal stresses that tend to express themselves as cracks while grinding. The grinding method is as ingenious as it is simple: a blank is fitted to a flat arbor and ground down by spinning it against a belt sander, on the side without the platen. A little WD40 for lubrication and thermal management helped while progressing to finer grit belts, with a final treatment using plastic polish yielded a shape very reminiscent of an old CRT face. There’s a Twitter video that shows the simulated CRT.
Old CRT computer enthusiast [x86VileR] recently tracked down an IBM 5153 monitor for which he had been searching several years. Unfortunately shipping a heavy glass CRT isn’t easy. In fact, it took [VileR] three tries to get a functioning monitor delivered intact and working. The first one seemed reasonably protected in its packaging, but arrived so banged up that the CRT had become dislodged inside the monitor and the neck broke off! The second attempt was packaged even better, and he was sure it would arrive problem-free. Alas, it too arrived all banged up and broken.
This one clearly had superior packaging, so I find it difficult to account for this truly stupendous level of damage. The most promising theory is that several people jumped on it simultaneously, just before the delivery truck ran it over. As my friend put it, it would’ve arrived in better shape if he had just smashed it himself before boxing it up.
Double-boxing appears to be the answer, although it might result in a box too large to ship depending on your courier’s rules. Short of building custom wooden crates, do you have any packing tips for shipping heavy and fragile items? Thanks to [J.R. Dahlman] for sending us the tip.
If you own an Apple product you probably live in a world with a few proprietary interfaces, but by and large your displays and desktop peripherals will use familiar ports such as USB and DisplayPort. For the Mac owner of yore though it was a different matter, as [Dandu] is here to tell us with the tale of a vintage Apple monochrome CRT monitor and a modern Mac.
There are no handy VGA ports to be found in this screen, instead it has a 15-pin D connector following a proprietary interface. With the right adapter it’s easy enough to produce VGA from the modern machine, but while it is in theory possible to map VGA pins to Apple pins there’s a snag with this particular model. Instead of using separate sync pins, it demands a composite sync of the type you might find in an analogue TV set that contains both horizontal and vertical sync pulses. The solution came through a simple transistor circuit, and then with the requisite settings on the modern Mac to deliver the 640×480 resolution it was possible to see a MacOS Catalina desktop on something more suited to a Mac II.
We’re accustomed to seeing giant LED-powered screens in sports venues and outdoor displays. What would it take to bring this same technology into your living room? Very, very tiny LEDs. MicroLEDs.
MicroLED screens have been rumored to be around the corner for almost a decade now, which means that the time is almost right for them to actually become a reality. And certainly display technology has come a long way from the early cathode-ray tube (CRT) technology that powered the television and the home computer revolution. In the late 1990s, liquid-crystal display (LCD) technology became a feasible replacement for CRTs, offering a thin, distortion-free image with pixel-perfect image reproduction. LCDs also allowed for displays to be put in many new places, in addition to finally having that wall-mounted television.
Since that time, LCD’s flaws have become a sticking point compared to CRTs. The nice features of CRTs such as very fast response time, deep blacks and zero color shift, no matter the angle, have led to a wide variety of LCD technologies to recapture some of those features. Plasma displays seemed promising for big screens for a while, but organic light-emitting diodes (OLEDs) have taken over and still-in-development technologies like SED and FED off the table.
While OLED is very good in terms of image quality, its flaws including burn-in and uneven wear of the different organic dyes responsible for the colors. MicroLEDs hope to capitalize on OLED’s weaknesses by bringing brighter screens with no burn-in using inorganic LED technology, just very, very small.
The technical details on the electronics side are unfortunately a bit light, as the page on the [Iontank] site simply says all of the internals were replaced with “solid-state hardware” and an Amiga emulator. To us that sounds like a Raspberry Pi is now filling in for the Amiga’s original motherboard, but that’s just a guess. The page does note that they went through the trouble of making sure the original mouse and keyboard still worked, so it stands to reason a couple microcontrollers are also along for the ride doing translation duty.
While we don’t know much about the computers, [Iontank] do provide some interesting insight into developing the faux CRTs sitting atop the non-Amigas. There were some promising rear-projection experiments conducted early on, but in the end, they decided to use a standard LCD behind a milled acrylic lens. This not only made for a perfect fit inside the original monitor enclosures, but gave the screen that convex depth that’s missing on modern flat panels.
From the perspective of a later decade it’s sometimes quaint and amusing to look back at the technological objects of desire from times past. In the 1980s for example a handheld television was the pinnacle of achievement, in a decade during which the Walkman had edged out the transistor radio as the pocket gadget of choice it seemed that visual entertainment would surely follow. Multiple manufacturers joined the range of pocket TVs on offer, and Sony’s take on the format used a flattened CRT with an angled phosphor screen viewed from behind through its glass envelope. [Niklas Fauth] took one of these Sony Watchman devices and replaced its TV circuit board with one that turned it into a vector display. The Sony Scopeman was born!
We like the Scopeman, in fact we like it a lot. There may be some discomfort for the retro tech purist in that it relies on butchering a vintage Watchman for its operation, but we’d temper that with the observation that the demise of analogue broadcast TV has rendered a Watchman useless, and also with the prospect that a dead one could be used for a conversion project.
[Niklas] has had more than one project appear on these pages, a memorable example being his PCB Tesla coil.
In his write-up he goes into detail on the path that took him to his component choices, and given the unusual nature of the design for 2020 it;s a fascinating opportunity to see the job done with components that would have been unheard of in the 1950s or 1960s. He eventually settled on a high voltage long-tailed pair of bipolar transistors, driven by a single op-amp to provide the differential signal required by the deflection electrodes. The mix of old and new also required a custom-fabricated socket for the CRT. On the game side meanwhile, an ATmega328 does the heavy lifting, through a DAC. He goes into some detail on DAC selection, having found some chips gave significant distortion.
All in all this is an impressive project from all angles, and we’re bowled over by it. Of course, if you fancy a play with vector graphics, perhaps there’s a simpler way.