In the home computer market of the 1980s, there were several winners that are still household names four decades later: the Commodore 64, the Apple II and the Sinclair Spectrum, to name a few. But where there are winners, there are bound to be losers as well – the Mattel Aquarius being a good example. A price war between the bigger players, combined with a rather poor hardware design, meant that the Aquarius was discontinued just a few months after its introduction in 1983. However, this makes it exactly the type of obscure machine that [Leaded Solder] likes to tinker with, so he was happy to finally get his hands on a neat specimen listed on eBay. He wrote an interesting blog post detailing his efforts to connect this old beast to a modern TV.
The main issue with the Aquarius is that it only has an RF video output, which results in a rather poor rendition of its already very limited graphics capabilities. Luckily, there is a fix available in the form of a composite A/V adapter that’s an almost plug-and-play upgrade. The only thing you need to do, as [Leaded Solder] illustrates in his blog post, is open up the computer, desolder the RF modulator and solder the A/V adapter in its place. Getting to that point was a bit tricky due to heavy EMI shields that were fixed in place with lots of solder, requiring liberal use of a desoldering iron. Continue reading “Adding Composite Video To The Mattel Aquarius”→
Today, acronyms such as PAL and initialisms such as NTSC are used as a lazy shorthand for 625 and 525-line video signals, but back in the days of analogue TV broadcasting they were much more than that, indeed much more than simply colour encoding schemes. They became political statements of technological prowess as nations vied with each other to demonstrate that they could provide their citizens with something essentially home-grown. In France, there was the daddy of all televisual symbols of national pride, as their SECAM system was like nothing else. [Matt’s TV Barn] took a deep dive into video standards to find out about it with an impressive rack of test pattern generation equipment.
At its simplest, a video signal consists of the black-and-while, or luminance, information to make a monochrome picture, along with a set of line and frame sync pulses. It becomes a composite video signal with the addition of a colour subcarrier at a frequency carefully selected to fall between harmonics of the line frequency and modulated in some form with the colour, or chrominance, information. In this instance, PAL is a natural progression from NTSC, having a colour subcarrier that’s amplitude modulated and with some nifty tricks using a delay line to cancel out colour shifting due to phase errors.
SECAM has the same line and frame frequency as PAL, but its colour subcarrier is frequency modulated instead of amplitude modulated. It completely avoids the NTSC and PAL phase errors by not being susceptible to them, at the cost of a more complex decoder in which the previous line’s colour information must be stored in a delay line to complete the decoding process. Any video processing equipment must also, by necessity, be more complex, something that provided the genesis of the SCART audiovisual connector standard as manufacturers opted for RGB interconnects instead. It’s even more unexpected at the transmission end, for unlike PAL or NTSC, the colour subcarrier is never absent, and to make things more French, it inverted the video modulation found in competing standards.
The video below takes us deep into the system and is well worth a watch. Meanwhile, if you fancy a further wallow in Gallic technology, peer inside a Minitel terminal.
In the United States, analog TV broadcasting officially ended in 2009. While the transition wasn’t without hiccups, we did lose something along the way. For [Emily Velasco], she misses the channels between channels — where an analog TV isn’t quite tuned right and the image is smeared and distorted. A recent bug in one of her projects led to her trying to recreate the experience of the in-between on a CRT.
One of [Emily]’s other projects involved generating composite video signals from an ESP32 microcontroller. While experimenting with adding color to the output signal, the image came out incredibly scrambled. She had made an error in the stride, which smeared the image across the screen. This immediately brought back memories of old analog TV sets. A quick potentiometer allowed her to control the stride error and she wrote some code to break the GIF up into discrete bitmaps for display since the GFX library handles GIFs differently than static images. Next up was vertical hold, which was accomplished by shifting the Y coordinates. With some help from [Roger], there was now a handy GIF library that would draw GIFs line by line with the composite video effects.
Just because a microcontroller doesn’t have a dedicated video peripheral doesn’t mean it cannot output a video signal. This is demonstrated once again, this time on the ESP32 by [aquaticus] with a library that generates PAL/SECAM and NTSC composite signals. As a finishing touch on the hardware side, [aqaticus] added an RCA jack is an optional extra. The composite signal itself is generated on GPIO 25, with the selection from a wide number of PAL and NTSC resolutions.
In addition, LVGL support is integrated: this is an open-source library that provides a cross-platform way to provide graphical UIs for embedded platforms. Using this combination any ESP32 can generate a fully graphical UI on a monochrome or color display to add some extra flair and functionality to an ESP32 project.
Currently, this library does not support color output, but hopefully this will be added in the future. Even so, together with simple VGA output using a DAC, this library provides yet another way to add analog video output to ubiquitous MCUs like the ESP32. Even if these MCUs are not going to be decoding any video formats at a reasonable speed, adding a UI that’s more user-friendly than an HD44780-based display and a few buttons can really elevate the user experience.
We’ve covered plenty of clocks powered by the ESP32, but this one from [Marcio Teixeira] is really something special. Rather than driving a traditional physical display, the microcontroller is instead generating a composite video signal of an animated digital clock. This could be fed into whatever device you wish, but given the 80’s synthwave style it’s pumping out, you’ll probably want to find a suitably retro CRT to do it justice.
Specifically this is a variant of the “Dali” clock, where each digit seems to melt and morph into its successor. Though his version doesn’t necessarily share code with all the previous iterations, [Marcio] does credit the developers who have pulled off similar visual tricks going all the way back to 1979. Given the vintage of this particular animation, the neon skyline and infinite scrolling grid certainly feel like a perfect fit.
Want to add a little vaporwave vibe to your own workbench? Assuming you’ve already got a 80s style CRT, all you need is an ESP32 and two wires stuck into the composite video port. One goes to ground, and the other goes to the chip’s analog pin. Once everything is powered up, you’ll be able to configure the clock with a web-based interface. It doesn’t get much easier than that.
[John Floren] found a nice old black & white TV in a thrift store, and as so many of us would, he decided to take it home. He was surprised upon getting it there that it had, in addition to the VHF and UHF antenna inputs, a mysterious extra connector on the back. Naturally, he set about investigating.
On the rear was an obviously hacked-in F-type connector, paired with a toggle switch, both unlabelled. Running the output of an RF modulator to the connector didn’t net an image on the screen, even though the same method worked when hooked up to the antenna inputs. Undeterred, [John] dug deeper.
Inside, a little PCB bearing the mark “TVM.04” was inside, bearing a handful of components. The device turned out to be a Pickes and Trout TVM-04 adapter, designed in the 1970s for hooking a computer up to a television for use as a monitor. The adapter board allows the Hitachi TV to accept a composite video input. [John] was able to test the TV with a NES clone outputting composite video and voila, it worked! [John] then went further, adding an audio input and installing standard RCA jacks to make it easier to use the input with more modern electronics.
While other video converters have all-in-one chipsets that are much harder to work with, [LoFi Future] explains that the separate EM636165TS DRAM chip on the GBS-8100 provides an ideal spot to tap in and wreak some technicolor havoc. By mapping out the pins and studying how the video output is corrupted by grounding them out or connecting them to each other, he’s been able to come up with fairly repeatable “recipes” for different effects.
In the most basic form, once you’ve soldered the pins of the DRAM chip up to the plug board interface, you’d technically be done. But [LoFi Future] takes it a step further and pairs the GBS-8100 with a separate composite to VGA converter. This provides some additional effects in the form of feedback loops and hue adjustment, but more practically, allows the device to handle composite on both the input and output. It’s a lot of hardware to cram into the enclosure, but thanks to little touches like the printed panel graphics, the final product does looks very professional.