The aim of this project is control the intensity of lamp. The intensity of lamp is directly proportional to the DC voltage applied across its terminals. Hence, if we control the voltage applied across its terminal, we actually can vary the intensity.
Here we use microcontroller from 8051 family. Two buttons are used as inputs to vary the intensity. PWM is generated at the output by using program burned into the microcontroller. The program can be written in Assembly language or in Embedded C. PWM (Pulse Width Modulation) wave can be used to vary the intensity. Here the average voltage given or the average current flowing through the lamp will change depending on the ON and OFF time of the pulses controlling the intensity of the lamp i.e. The duty cycle of the wave controls its intensity.
The power supply consists of a step down transformer 230/12V, which steps down the voltage to 12V AC. This is converted to DC using a Bridge rectifier. The ripples are removed using a capacitive filter and it is then regulated to +5V using voltage regulator 7805 which is required for the operation of microcontroller and other components.