They are a couple of resistors and a capacitor. Using just additional three components, we can make the 555 Timer to work in Astable Mode.
Hence, an Astable Multivibrator is also known as Free Running Multivibrator or Free Running Oscillator. How 555 Timer Works in Astable Mode?Īs the name suggests, an Astable Multivibrator is an oscillating circuit without a stable state i.e., it automatically switches between the two states. Once you understand this, then by making small modifications, you can effortlessly produce a PWM signal using 555 Timer. But before seeing how 555 Timer PWM signal is generated, you need to understand the Astable Multivibrator operation of 555 Timer IC. It is vey easy to generate a PWM Signal using 555 Timer IC. The above image shows different PWM Signals and different Duty Cycles along with the output voltage. If T HIGH is the duration for which the pulse is HIGH in one cycle and T LOW is the duration for which the pulse is LOW, then period of the pulse isįrequency of the PWM Signal describes the rate at which the signal completes one cycle. The “Duty Cycle” and the “Frequency” of the PWM Signal determines the output voltage.ĭuty Cycle of a PWM Signal describes the amount of time the pulse stays HIGH in one cycle. In the PWM technique, the voltage that must be supplied to a DC Motor or an LED is supplied in the form fast switching pulses rather than a continuous analog signal. It is generally used as a power delivery mechanism in motor control and lighting control systems. PWM, short for Pulse Width Modulation, is an important concept in modern electronics.