I’ve been playing around with a few DC-DC buck converters similar to these ones: https://www.amazon.com.au/UEB-Power-Converter-Module-Supply/dp/B078CXHWXC/ref=sr_1_fkmr1_1?ie=UTF8&qid=1519030369&sr=8-1-fkmr1&keywords=mini+360+buck+converter
I had expected 5v output from my 12v supply but when I hooked it up to a multimeter I found I was getting just over 10v. This would fry pretty much everything in my circuit so I was pretty worried.
After a bit of research, I came across a thread on eevblog that mentioned a screw for adjustment. Looking closely you can see that there is a small screw on the side of the chip. Turning this quarter of a rotation anti-clockwise put mine at exactly 5.04 volts.
A few other small tips:
- The thread seems to indicate that some models require a lot more turning (up to 30 seconds for one poster).
- I had to push down fairly hard to get it to actually turn the part underneath instead of just the metal cover
Hopefully this helps someone else out!