So I am building up my first stand alone Arduino project which will need a 5VDC power supply. The project controls 120VAC so powering it up off a wall wart is stupid. Going to do it on board. Best estimate i can guess is that i will need about 300ma current so I plan to build in 800ma to 1000ma capacity just in case I am way wrong. Inefficiencies etc etc. After much reading and video watching I bought 161K12 Power Transformer from Hammond Manufacturing. I don't know what i was smoking, this thing is rated for 10VA. That's way more then I should need? Was thinking more like 3-4VA to be on the safe side? Anyhow it's huge and heavy. So I looked on Mouser for a smaller one. I can find some that are about 4VA but only 6.3 Volts Out. I think that is not correct. What I want to know is what the heck are the Chinese doing inside there little tiny light 5vdc 1000ma power supplies. They feel like all air. I would cut one open to see but I need the one I have for a customer and the rest are all in use. Are they Non Regulated? Linear? Switch Mode? I don't even know. I figured they would just be an unregulated piece of crap. All the tiny transformers I find are rated for audio and on 30volts or so. Some one please give me a clue. No, I don't want to just buy a wall wort and steal the parts every time. I want to just be able to order 10 or 20 small transformers and rectifiers and use them in my designs. Hope someone can help.
Update: I found a 3.3v 300ma wall wart I didn't need very similar in size and weight to the 5vdc one. So I looked inside. It looks like a linear regulated type just with a super small transformer.No writing on the transformer. Where can I get these small transformers rated for 155vac on the primary please? All I can find online are old school iron core clunky ones.