7/24/2019 THE 555: A Versatile Timer

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I_FUNCTTONAL

BLOCKSOF

THE

555TlMFB:with

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dentitied

IN ANY

ASSOCIATION

TEST FOR''

those

who

know integrated cir-

cuits,

the three

digits 555

will

summon

up the

instant

re-

sponse

"timer

IC."

It's

the

short

form

generic

designation for

progeny

of the

N8555,

a

popular

monolithic

timer/oscillator

IC

first introduced

by Signetics

manyyears

ago. Still

widely sec-

ond-sourced

because

of its ver-

satility,

the

555 ranks

as a

standard

"building

block.

"

The

555

and

its derivatives

can

be found

in thousands

of

different circuits,

and

its

pos-

sibilities

for further

applica-

tions appear

limitless.

Al-

though

classed

as

a

linear

IC,

it

is

often used

in

digital

or

"quasi-digital"

applications

be-

cause its inputs

and outputs

are essentially square

waves

circuits

to

obilini.cc':tte:,,tgdelayg

d

sqa.re

waves

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