ab1jx wrote: ↑
Sun Aug 13, 2017 5:19 pm
The horizontal and vertical refresh rates in typical analog televisions are much slower than in computer monitors, you'd burn it up. In the 1940s or so when the standards were established there was no need to go fast, it was a miracle to have it work at all. "In analog television systems the horizontal frequency is between 15.625 kHz and 15.750 kHz." from https://en.wikipedia.org/wiki/Horizontal_scan_rate
As long as you select the correct video standard on the Pi, this is not an issue. Analogue inputs designed for old TV standards certainly won't like high definition video.
You can simulate a composite input (RCA jacks) by using an RF modulator. Used with video games to produce a TV signal, fairly often there's a sound input. Typically switchable between channels 3 and 4. There are one or 2 ICs that do that single handedly, you can find those in an old VCR. LM 1889 or 2889, maybe some others. A lot of work to use though if you start from scratch. I'm in the US and I used to be a TV technician, so I'm talking NTSC, I assume something similar is available for PAL. Pretty much any of these, don't pay much because millions of them have been thrown out: https://www.google.com/search?output=se ... 3472226903
The quality of signal from an UHF modulator into the aerial socket will be unusable in most cases, NTSC or PAL.
You could also pick up an old VGA monitor cheap or free and use an HDMI->VGA adapter. I have my Zero hooked up that way to an old CRT VGA monitor. My adapter was cheap and it's either passive or self-powered from somewhere, there's no power connection. Monitor was free, adapter was maybe $10.
That was where the thread started. Passive converters don't always work. (AIUI, many rely on signals defined for HDMI but not implemented on the Pi.) It may be possible to find an active converter powwered over the HDMI link.
My take on it all so far: there are two options, an active HDMI to composite converter, or solder on to the Pi's composite output and build a separate sound output stage. Either way you need a cable to provide the Scart connection. Either way you need to configure the Pi for the right signal out, though this may be less critical with a converter. No-one can guarantee that either solution will work for you, unless they just happen to have the same TV and can recommend parts that you can still find.