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Question from reader: Pull-up resistor

Question from reader: Pull-up resistor

QUESTION: I am unable to understand Pull Up and Pull Down resistor. why and when to use this.. Can you please help me..

OYVIND: Pull-up and pull-down resistors are used for example on digital inputs on a microcontroller. They make sure you have either a valid 1 or 0 at the input, when nothing else is connected.



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A pull-up resistor is connected from the input and up to the positive power supply. It pulls the input up to a 1, when nothing else is connected.

A pull-down resistor is connected from the input and down to ground. It pulls the input down to 0, when nothing else is connected.

Keep on Soldering!
Oyvind

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