It would be hard to find any electronics still in production which use CRT displays, but for some inscrutable reason it’s easy to find cheap 4-inch CRTs on AliExpress. Not that we’re complaining, of course. Especially when they get picked up for projects like this Retro CRT Weather Display from [Conrad Farnsworth], which recreates the interface of The Weather Channel’s WeatherStar 4000+ in a suitably 90s-styled format.
The CRT itself takes up most of the space in the enclosure, with the control electronics situated in the base behind the display driver. A Raspberry Pi Zero W provides the necessary processing power, and connects to the CRT through its composite video output.
A custom PCB plugs into the GPIO header on the Raspberry Pi and provides some additional features, such as a rotary encoder for volume and brightness display, a control button, a serial UART interface, and a speaker driver. The design still has one or two caveats: it’s designed to powered by USB, but [Conrad] notes that it draws more current than USB 2.0 can provide, though USB-C should be able to keep up.
On the software side, a Python program displays a cycle of three slides: local weather, regional weather, and a radar display. For the local and regional weather display graphics, [Conrad] created a static background image containing most of the graphics, and the program only generated the dynamic components. For the radar display, the regional map’s outlines come from Natural Earth, and a Python program overlays radar data on them.
We’ve seen other attempts at recreating the unique style of the WeatherStar system, but nothing quite beats the real thing.
I’ve been looking for an excuse to buy one (or more) of these CRTs, still not there yet but I quite like the idea of a “handheld” gaming console with a selection of vintage games like space invaders
I’m sort of obsessed with how old pixel art games like Third Strike just look a million times better on CRT. Like the CRT “filter” is an integral part of the medium that the art is made for.
If you could match an LCD with a vintage system pixel for pixel I think it might be better, but feeding the low resolution output from a vintage system to a super sharp, hi res LCD is always going to show up the shortcomings.
I do like a well set up CRT display though, they look nice and yeah, they make vintage hardware look better because it was designed for the foibles and shortcomings of a CRT display but that’s a religious war
There’s a difference between a domestic CRT TV and an arcade CRT, though.
An NES or Genesis console looks fine/authentic on a “blurry” 1970s/80s era NTSC/PAL TV with RF jack,
while an arcade cab had CRTs with RGB input and razor sharp pixels and thick scan lines.
Same goes for Amiga/VGA PC DOS games of old.
The Commodore 1084s monitor had a dot pitch of 0.42 mm, the IBM PS/2 8513 monitor a dot pitch of 0.39 mm.
Both were quite low res compared to mid-90s and 2000s CRTs (good).
Such details do matter, it’s a rational consideration.
A random CRT monitor doesn’t cut it; it has to match the source.
A low res source and a low res monitor match each other, for example.
The dot pitch on my 90’s Nokia monitors was 0.25×0.22mm and they had both rgb and sync input. Being forced to switch to LCD was a serious downgrade for many years.
At this point using a shader to approximate the effect dynamically based on resolution and the game source is generally a better way to go (blasphemy, I know) they aren’t perfect, but have gotten much better over time.
Hi, early VGA monitors of the 80s were more like this.
https://www.youtube.com/watch?v=m79HxULt3O8
Dithering worked very well here, have a look at Monkey Island part.
It wasn’t very good for GUIs such as Windows or GEM.
By time Windows 95 came out, such DOS era VGA monitors were obsolete.
Which is sad, because mode 13h games looked gorgeous on them.
Here’s a decent explanation, I think.
https://www.datagubbe.se/crt/
I was expecting a regular CRT. I’d try an audio scope with one of these like I did with one this size I found in the trash. It has a radio too so it’s self contained with a FM source. Internal audio amp drives the former horizontal and the former vertical becomes the timebase with the yoke turned 90 degrees. The only trick is a small inductor to load the unused horizontal to continue to provide anode voltage.
Wild guess here… is the speaker melting because it needs a DC blocking capacitor?
You’re the second person to suggest this. I think it’s the right fix but neither the datasheet or Adafruit’s version of the breakout board for the DAC chip include a blocking cap. It would probably be wise to add one in though.
What a cool project! Classy form factor, too
Looking at the pics here and some customer pics on AliExpress, it seems that the images on these CRTs tend to droop downward on the left side. Anybody have ideas on that?
Slightly maladjusted yoke? Or maybe the original circuit had some electromagnetic component there which was compensated for? I’m just guessing
That’s a really interesting question, and I’ve been kinda chewing on it all afternoon, since I’ve noticed the same thing. I think some distortion may be inherent to the design of the CRT; Even the Sony Watchman didn’t have perfect geometry. My best guess is that it’s related to incorrect compensation for the odd geometry of the CRT. Whether this is due to yoke maladjustment / misalignment / defect as TG suggested, or an issue with a compensation circuit for the sweep signals, I’m not sure. I can’t imagine the deflection signals for this CRT would be linear ramps, given that the axis of the electron beam is nearly parallel to the surface of the screen. It’d be interesting to throw a scope on this and see what things look like. I’m also curious how good focus is maintained across the entire screen. Unfortunately, the equipment for manufacturing these has probably long been scrapped, and the hands-on engineering knowledge being slowly lost to the sands of time. It’d be interesting to know the circumstances that led to enormous numbers of these coming up for sale (did someone find thousands of them in a Chinese warehouse?) Either way, I’m gonna buy a few of these before they disappear.
“but for some inscrutable reason it’s easy to find cheap 4-inch CRTs on AliExpress”
oh wow very inscrutable. It´s called stock / stockpile.
Why here is word salad so often taking precedence over rational thinking and fact-checking ?