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LED's connected to a 9V AC/DC transformer and something went terribly wrong Answered

I recently did a project with 4 LED's 3.3V 25mA 2 in each series (2 parallel circuits). I know i wasn't drawing too much from the transformer but my transformer still melted(ish). It was connected to a switch, but i may i had it connected wrong. I searched for shorts first, and couldnt find any. Would this happen becuase i connected the switch incorrectly? I cannot find much information on using AC/DC transformers for LED's....I was looking to save money on batteries for my projects.



7 years ago

Do you know the actual current draw from the transformer when it failed?

Were your LED's damaged? If so you may not have had a current liminting resistor in series with them, or your resistor was too small a value.

If you had connected your switch in parallel with the LED strings instead of in series, then the transformer would have been directly shorted out.

It's hard to say without a diagram, but the things I listed above are the more obvious ones that come to mind.


Answer 7 years ago

Ahh i was so stupid, the resistor i was missing one....obvious answer thank you!