People have grown up with the sights and sounds of fluorescent lamps buzzing to life after a few attempts. As the new wave of energy saving appliances gripped the world, technology made the fluorescent lamps shrink in thickness as well as reduced the number of attempts made by lamps to shine their brightest. Today many homes use energy Saver CFL lamps and fluorescent tubes which start giving light the moment they are switched on. This instantaneous production of light is achieved by the use of electronic ballasts. Ballast is a device which controls the starting voltage and the operating currents of lighting devices built on the principle of electrical gas discharge. It refers to that part of the circuit which limits the flow of current through the lighting device and may vary from being a single resistor to a bigger, complex device. In some fluorescent lighting systems like dimmers, it is also responsible for the controlled flow of electrical energy to heat the lamp electrodes.  

Electronic ballasts are gradually replacing conventional magnetic ballasts (commonly known as choke) from the fluorescent tubes.  They have higher efficiency as compared to magnetic ballasts and provide a flicker free start up to the tube.  Also it does not produce the ‘hum’ sound which is very annoying with the magnetic ballastElectronic ballast uses semiconductor components and operates at 20 KHz-80KHz unlike the magnetic ballast which operates at 50 -60 Hz. At high frequency the lamp requires less input power, thereby increasing the efficiency. When power supply enters in to the ballast circuit, it first goes through an EMI filtration to block the ballast generated noise. Capacitors are used for the same.