I have made a few power supplies in the last year (only linear ones using voltage regulators). I have always used a big simple step down transformer, from 230v down to 12/24v (depends on the supply i need).
There are a lot of circuits out there on how to make the power supply for the LM2678 but from what I've seen no one writes about the transformer. From what i know, since SMPS operates at a high frequency i can use a smaller transformer?
I have a lot of small yellow ones that looks like this:
But since i don't know much about smps transformer, and i really don't want to play around with the 230v ac to find out where the primary/secondary of the transformer is. I wanted to ask you guys if you could tell me a little more about what transformer i should use and why.
I first thought of using a step down transformer from 230v down to 6v ac, and then use a resistor to limit the current to like 10mA and use that to find the primary of the smps transformer because that would be safer right?
Any tips are appricated! Thank you.
PDF to the LM2678: