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RE: LM7805 voltage drop when attach load

Sorry, wrote that in short hand. Your circuit is designed to provide up to some amount of current to the input of the 7805. Since the voltage is being pulled down on both sides of the 7805, you are drawing more current than the input side is designed to supply. You should be able to find the cause of the problem with an ohm meter. You will probably see a low resistance reading from the output of the 7805 to ground. You can lift one leg of the components on the load side of the 7805 until you find the problem.

If you don't see a low resistance to ground on the load side, you could have a problem on the supply side that doesn't allow enough current to be supplied to the 7805. That is why I suggested measuring across a resistor in series to see how much current is being supplied when the voltage is being pulled down. I = V/R

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  • RE: LM7805 voltage drop when attach load - fredtr 13:47:50 06/26/17 (0)


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