OVERHEAD PROJECTOR LAMP LIFE EXTENDER BY ZVS (ZERO VOLTAGE SWITCHING)

Model no.7:

             Incandescent lamps exhibit very low resistance in cold condition. Thus at the time of switching from cold state it draws very high current. Thus many lamps fail at the time of switch ON. Engaging two SCR’s in anti parallel or a TRIAC the switching ON time can be precisely controlled by firing after detecting the zero cross point of the waveform of supply voltage. This should result in current waveform rising from zero at the time of switching ON there by increasing the life of lamp. The project is having comparator which is used for ZVS output. The ZVS (ZERO VOLTAGE START) is given as reference interrupt to microcontroller. The microcontroller is of 8051 family which is of 8bit. In this we are using push button as switch which is used as reference interrupt to microcontroller and using that interrupt we give signal to opto-isolator. The opto-isolator used in the project is used as switching element using this we will trigger the back to back SCR. On the base of SCR triggering the AC lamp can be controlled to ON at low voltage. 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 a voltage regulator 7805 which is required for the operation of the microcontroller and other components.

For more details about this project, please visit    http://www.efxkits.com/project-kit/electrical/1116.html

HARDWARE REQUIREMENTS:

Microcontroller (AT89C52/S52), LM358, Opto Isolators, TRIAC, Transformer, Diodes, voltage regulator, push button, LED, Resistors, Capacitors, Crystal oscillator, Load.

SOFTWARE REQUIREMENTS:

Keil compiler, Languages: Embedded C or Assembly

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