Skema Rangkaian Oscillator LM555

LM555 Astable oscillator Circuit.

Circuit oscillator astable

Frequency of the output pulses is determined by the values of two resistors, R1 and R2 and by the timing capacitor, C.

To calculate the frequency (F):

To calculate the the On time or Off time:

Before calculating a frequency, you should know that it is usual to make R1=1 kΩ because this helps to give the output pulses a duty cycle close to 50%, that is, the HIGH and LOW times of the pulses are approximately equal.

LM555 Monostable oscillator Circuit.

circuit oscillator monostable

Trigger input is held HIGH by the 10 kΩ pull up resistor and is pulsed LOW when the trigger switch is pressed. The circuit is triggered by a falling edge, that is, by a sudden transition from HIGH to LOW. The trigger pulse, produced by pressing the button, must be of shorter duration than the intended output pulse.

To calculate the period (t):