How a PULL UP and PULL DOWN Resistor Works

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Introduction: How a PULL UP and PULL DOWN Resistor Works

About: This is Electronic Project Forum which aims to help new members to build easy D I Y ( Do It Yourself ) Electronic Projects

IN THIS INSTRUCT ABLE I AM GOING TO SHOW YOU

(1) HOW A PULL UP AND PULL DOWN RESISTOR WORKS

(2) HOW YOU WILL CONNECT A SWITCH IN A SAFER MODE

(3) AND THEIR APPLICATION

A COMPLETE DETAILS IS ALSO GIVEN IN THE VIDEO DESCRIPTION AS WELL...

Step 1: How a PULL UP an PULL DOWN Resistor Works...

PULL UP AND PULL DOWN WORKS ON A BASIC PRINCIPLE OF VOLTAGE DIVIDER

FOR PULL UP

if the switch is open and considered to be ideal switch ie (resistance = 0) all the voltage is drop across the 10K resister giving 5volt at output

but

if we closes the switch zero voltage is drop across the switch due to ideal switch condition.....

SIMILARLY

The PULL DOWN will work in a reverse manner....

Step 2: How to Connect a Switch in a Safe Mode

Mostly used is pull up condition coz

in pull down if we closes the switch some high amount of current will pass through the switch and if the switch is not capable of passing this current then switch will be damaged...

while in the case of pull up resistor will resists some current and we have less chances of damaging the switch

BUT BE CAREFUL WHILE USING THE SWITCH CHECK THEIR CHARACTERISTICS FIRST

Step 3: Application

PULL UP and PULL DOWN resistor used in micro controller to give the logic signal HIGH and LOW

Let say we have arduino and we configured one pin as an input pin so

arduino will not know exactly which signal is at their input pin (high or low) so pull up and pull down will resolve this issue

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    14 Discussions

    Is that your youtube video? I can't make out what you're saying since you have the microphone too close to your face, and the music does not help either :(

    2 replies

    sorry for my bad voice
    I written all the things in my instructable

    Don't get me wrong - Your voice isn't bad, it's just the music and the microphone being too close to your mouth. Good tutorial otherwise :D

    I'v been using using them for 20 years and have not given any thought to them, thanks for the article.

    1 reply

    before you knew it, it was not basic at all

    yes piper
    I know this thing when I was in my first year of engineering
    and I realized their importance now a days

    isn't his backwards? the meter in your example, usually a state gate, is extremely high R so that little to no current flows into it.....thereby making both circuits ope (or floating) when the switch is open. closing the switch in your "PULL UP" diagram will actually allow current to flow to ground thereby "pulling down" the meter input to 0. Conversely, closing the switch in your "PULL DOWN" diagram will "pull up" the input to source voltage......

    1 reply

    yes you right
    there is some amount of current leaking depend on the instrument you have ....
    but here we are considering the ideal case

    Amazing tutorial. Really helpful

    Great tutorial. I can't tell you how many times I have forgotten to use a pull down resistor my one of my circuits.

    1 reply