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does the negative or positive cable from a power source go to pin 1 on a 5v regulator? Answered

i am working on a solar usb charger and everything i have read about 5v regulators says to connect the positive cable to pin 1 and the positive of the usb to pin 3.  this doesnt seem right because th voltage wouldnt actually be taken down would it. I feel like the negative ends should be connected to the pins. am i right?

3 Replies

Re-designBest Answer (author)2010-06-10

Without knowing EXACTLY what you're trying to do it's hard to help you.

Look at this diagram.  The neg from supply goes directly to the neg of the load.

the pos from supply goes to pin 1 of the 7805 regulator and pin 3 is the regulated output that goes to the load.

I "think" that the voltage that is lost goes thru pin 2 back to negative but I could be wrong on that.

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lemonie (author)2010-06-10

Regulators work by taking a voltage down to a regulated-level. Connect it as per a good diagram, you'll need much more (%) than 5V input. L

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steveastrouk (author)2010-06-10

No, you've forgotten pin 2.
Wire 1 to the input, 2 to the negative, 3 to the output.

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