Hi,

I'm an absolute beginner and your help would be much appreciated.

I'm building a small etching/marking device with an old 12V DC power adapter. I use the 12V DC output to etch metal and I want do use 12V AC to mark the steel. It seems that I cannot locate the 12V AC on the board. I soldered 2 wires (red) were I thought that I can find 12V AC. It's were 2 wires are connected to the board, coming from the transformer. Well, that did not work.
I have no multi-meter, so I'm not sure how to find the right place.

Any help would be great!

Thanks,

 

This is dangerous! Especially for absolute beginners and with no multimer. This might be an impulse transformer in which case you will measure "12 VDC" on the output.

 

ArkelTheDragon is rigght. It is dangerous and being a switching power supply you won't find 12VAC on the board.

You need a wall wart with a 50 Hz or 60 Gz transformer in it, or such a transformer. They are much heavier than those in switching power supplies. Remember to include a fuss in the transformer's primary.

 

That is a Switchmode psu ,these work on High Voltage DC, rectified ftlrom the mains input...
you need an ordinary transformer type psu.

 

Ok thanks, that's what I thought. How do I know that it's not a switchmode psu without opening it? Only by weight?

 

Would this work? https://www.digikey.ca/product-detail/en/triad-magnetics/F-218X/237-1937-ND/5032178