2020م - 1444هـ
The 555 timer is a single-chip version of a commonly used circuit called a

multi-vibrator.

• It is used in a variety of timers, pulse generators, and oscillator applications.

• The 555 timer IC contains a lot of transistors, resistors and diodes. It has

three 5 kΩ resistors, thus has the name 555 timer.

• We use 555 timers to produce an oscillated output.

• For example, we can use a 555 timer to make an LED blink ON and OFF.

• 555 timers allow us to choose how frequently this blinking should occur

(frequency). If we control the frequency, we are indirectly controlling the time,

thus the name ‘timer’.

• The chip can be used for timing functions such as - turning on a light for a

period of time, a warning light to flash on/off and produce musical notes.

• The 555 timer IC operates in three modes which are, astable mode,

monostable mode, and bistable mode.