Transformerless Power Supply

Transformerless power supplies are those units which do not employ any kind of inductor based device for transforming a certain level of input power to another desired level.
These work mainly using a capacitor for the required stepping up or stepping down an input power to the required magnitudes.
Under this category we specifically deal with transformerless power supply circuits designed to step down the mains 220V AC or 120 AC to some lower levels such as 12V, or 6V etc.
Such circuits are also called capacitive power supply circuit since these use a high voltage capacitor for stepping down the mains input current to the lower acceptable limits.
therefore these circuits basically bring down the high input alternating current to lower levels, but the voltage level is not transformed.
And because of this a zener diode or a transistor based voltage stabilizer is normally employed for controlling the voltage level.