Intel486dx33 wrote:

What is a good CF-IDE adapter to use with a 486 computer ?
There are so many but which one a better quality and actually work ?
Some of these CF card adapter are really cheap and break after only one use.

Most CF to IDE adapters are very basic little things that just adapt the physical CompactFlash pinout to an IDE pinout, which are compatible. These typically operate on 5v, which most CF media supports.
All of the ones I've tested so far (about 3/4 different types) each work with my 486 / pentium PCs as long as they're fitted the right way round and there are no shorts (both of which I've done, both my fault).
The one I currently use in my Packard Bell 486 is the same as your top picture, having a slot on the back is extremely handy.

You can get nice ones, like your second picture that have a voltage regulator. These can operate CF cards that support 3.3v at 3.3v. Most media handles both voltages but I read that features like UDMA might only work when operating at 3.3v. I also had a microdrive that nearly burned up running at 5v that was meant to be at 3.3v.
On your second pic, there's a connector for a 44pin IDE cable, which as far as I'm aware is usually for industrial applications, not so useful for what we're doing 😀

I use the Startech ones like in the first picture. Zero issues on several of my builds, ranging from a 75MHz Pentium-S up to a 550MHz Pentium III. I use Sandisk Extreme CF cards.

https://www.amazon.com/StarTech-com-Compact-F … F/dp/B0026OYEEQ

Then I usually mount them in a 5.25 bay IDE caddy.

https://www.amazon.com/inch-Hard-Drive-Mobile … /dp/B019QW83VK/

^--or I just use 3M sticky tape to mount them in smaller cases that don't have a spare 5.25 bay or spare PCI slot.

It is really common practice to use CF cards in a lot of industrial stuff, like this SBC 486 that I have. (well, it is 486 instruction set, but 800MHz)