I had an old usb harddrive caddy sitting about that only worked with IDE drives. I also had an old usb to ide (both 2.5 and 3.5 drives) and sata drives with no power supply. I also have a variable PSU.
I have a pile of old harddrives that I needed to check the contents of, and rather than buy a fancy usb dock from ebay I decided to recycle my old parts. This is what I ended up with:
I can then use my new harddrive PSU to power any external drive and the usb to sata / ide to connect it to a computer:
I needed it because I had bricked my NAS drive [I set root’s shell to a non-existant file and needed to edit /etc/passwd to fix it]