How to play old game consoles on modern TVs and monitors?

Seeing this thread here, I felt like playing some old consoles.
The thing is, I don’t have a TV with RCA input anymore.
In fact, I probably don’t even have a working TV around here.
So I have to use a PC monitor with HDMI, DVI, or VGA input.

And that raises the question. How do I connect an old console with RCA output to a more modern monitor with HDMI input?
On Mercado Livre I found these mini upscalers:


but I saw reviews (from other countries) with mixed results. In some, there’s no color; in others, the color is too saturated; in some, there are artifacts in the image; in several, there was buzzing (but I’m not worried about sound because I wouldn’t even run it through the upscaler; I’d send it straight to a speaker).
This variety of results is probably because this is the typical Chinese product that has been copied en masse and sold without any quality testing.

So the questions remain.
Has anyone tested these mini upscalers? Do they work?
Does anyone have any suggestions for a cheap solution that works reasonably well?

In the analog era, it all depends…

If the output is in black and white, it’s because the equipment doesn’t use the country’s color system (the US uses NTSC at 60fps on TV, and Europe uses PAL at 50fps). If there’s no sound, it’s because the audio system isn’t supported, or the format identifies the converter as a

You would need to match your console’s analog protocol (PAL → European // NTSC → American // Brazil → PAL-M) with the TV’s. I think it’s better to check at Brazilian stores that offer good warranty and return policies in case something goes wrong.

If you don’t mind not playing directly on the original console, it’s worth picking up the mini versions that already come with HDMI. Even though it’s emulation, Nintendo did a really good job with the customization on the NES and SNES — performance is better than a generic Raspberry Pi or PC (in the PS1’s case, there’s no difference from the Raspberry Pi, but it’s also good).

If you prefer to actually play on the consoles, there are two options: get a good version of those signal converters (which are quite expensive) or take it to a retro console shop that can mod the device to use an HDMI input (for some consoles there are Chinese boards that do this). If you’re handy with electronics, it’s even cheaper.

That happens when you have a bunch of reviews of different products. hahaha

But there are some that are quite decent. For example, this one gets good reviews: Amazon.com: Neoteck Mini AV RCA to HDMI Converter, Alloy Case Version, CVBS Composite to HDMI Adapter for TV PC PS3 STB VHS VCR Blue-Ray DVD Players Projector : Electronics