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Topic: Alimenting Arduino UNO with 9v DC NON REGULATED? (Read 1 time) previous topic - next topic


Hello everyone, I am kind of a beginner with arduino, I tried to search the web and the forum before posting this topic. Please forgive me if it is stupid:

I have a 9V AC source, I will use a rectifier (or 4 diodes I am not sure yet) and a capacitor to convert it to DC, can connect the Vin pin of my Arduino UNO to it to power the arduino? or should I use a regulator?



Yes, this should work. You are essentially constructing a DC wall transformer by taking an AC source and rectifying it.

Depending on how much current you will be drawing from this power supply, your voltage may drop below the 6.5V or so needed for proper regulation. Sizing your DC capacitor will become important, as is the characteristics of the 9VAC source itself of course.

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Thanks for the quick reply. That was also my first thought, but wanted a more experienced opinion.

Now a trickier question :):

I know that the capacitor will influence the AC source, would that be problematic in case I need the original 9vAC to remain intact? (I need the wave form to remain a nice sine and the voltage to be as authentic as possible, it is to measure the wall socket RMS).

Thanks again


Well, you're going to be in for a surprise if you think you're going to see a nice sine wave to begin with :)

Any load you place on your AC transformer (i.e., current draw) is going to distort the signal, either in shape or in amplitude, unless you have a "perfect" AC transformer (don't bother looking for one). The bigger (higher power) the transformer the less you will distort the wave.

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So I should probably aliment my arduino from another source, independant from this AC-AC transformer.

Thanks again RuggedCircuits.

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