Help buying PSU

Hi! I’m using my pi4b with an attached usb 3.0 SSD (just for the system and services) and I want to connect an additional 2.5 or 3.5 hdd for storage and media files.

Currently I’ve been able to use both through the Pi power only, despite having to use the storage hdd through USB 2.0 and I every now and then I experience power issues (clicking sounds) but overall, it works.

Now, I want to improve the stability of the system so I’ll buy a SATA-USB adapter with dedicated PSU for the non ssd disk and leave the pi power just for the ssd drive.

The question: will this adapter work for both 2.5 and 3.5 hdds without drawing any additional power from the pi? I rad online that someone had success with 3.5 drives but not with 2.5 because it would use 5v from the pi anyway. Does that mean that the 12v supply can’t deliver 5v?

Sorry if it’s dumb what I’m asking.

Thank you!

I had issues with my 2,5" drives (two HDDs and one SSD used on 2 differen RPis) because of power spikes and I use similiar adapters. One with 9V input and 2 with 12V input and it works just fine.
So I would say: Yes, this should work.

Did you have the issues with those adapters? Which ones are you using?

No I had issues without any adapters.
I use one of these: https://i-tec.pro/en/produkt/usb3stada-2/
And two of these: https://www.conrad.de/de/p/renkforce-festplatten-adapter-1x-usb-2-0-stecker-a-1x-sata-kombi-stecker-7-15pol-30-00-cm-schwarz-1490971.html#productDownloads

In general we recommend to power all drives connected on a RPI. Simply, USB ports of a RPI are not designed to power thinks larger than a USB pen stick.