Doing Power Supply Science

“Remember kids, the difference between science and screwing around is writing things down”

I put red and green LED’s in one of my FC power supplies and yellow and blue in a second one. I didn’t realize at the time, but this was actually quite helpful for me to keep track of which is which.

I have two AC wallwarts - one which says the output is 12v but actually provides 13.5 and another is labeled 9v and provides 11.22. Its nice to see consistency isnt a problem that is limited to me. Apparently manufacturers have a difficult time with it as well.

With all that said, I did some comparative testing with both of the wallwarts and supplies, making notes of the outputs.

12v wallwart - (13.5ac) redgreen -14.85 +12.20 yelblu -12.07 +12.17
9v wallwart - (11.22ac) redgreen -11.72 +12.20 yelblu -12.06 +12.17

If I had to guess, I would say the redgreen powersupply might have a bad 7912. Thats the one on the negative rail.

Is that voltage measured under load? I’m guessing not. An unregulated supply will usually read high without a load but drop down with a load.

https://www.sparkfun.com/tutorials/103

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Yes, this is with no load. Good to know!

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