Not a transformerless power supply!

KMoffett

Well-Known Member
I see many posts of people wanting to drop AC line voltage to 5VDC to run some circuit..."without using a transformer". I think they're trying to save either money or space. Though I have done that, I find that in the long run I don't really saved either...and I've added the risk of a non-isolated supply. It was usually to add a small low voltage source inside a devise that already had line-voltage internally and didn't want the add a cheap, external wall-wart plus internal regulator circuit.

When cell phone manufacturers started using switch-mode power supplies in their chargers I found the perfect source for small, isolated, wide range AC voltage, relatively high output current power supplies.