Page 32 - Template EBook Kita (A4 Document)

TOPIC 3: ASTABLE MODE

A BRIEF INTRODUCTION OF THE TIMER CIRCUIT

ASTABLE MODE TIMER CIRCUIT

In the Astable Mode, the 555
becomes an oscillator producing
continuous pulses at frequencies up
to 2 MHz.

The output continually switches
between the high and low states,

producing a square wave.

An astable circuit has
NO STABLE state.

Timing components consists
of two resistors, RA and
RB with a capacitor, C that
controls the delay time of
output timer.

The capacitor C is periodically
charged and discharged between
the trigger level VL = 1/3 VCC and

the threshold level VH = 2/3 VCC.

23