I already posted about transformerless power supplies in the article, Transformerless DC Power Supply. Here we will see how to design a capacitor dropper power supply. Capacitor power supplies are simple, low cost and light weight solution for providing dc supplies to circuits which require low currents. It is low cost and light weight since there is no bulky transformers.
Capacitors are passive two terminal electronic components that has a wide variety of applications from oscillators to power supply applications. One of the important application of capacitors is power line filtering which is used in many electronic devices and appliances. Capacitors used for these applications are categorized as X and Y rated capacitors. These capacitors are also known as EMI/RFI suppression capacitors or AC Line filter safety capacitors. These capacitors can supply various protective measures and operational insulation to various electrical and electronics equipment.
