This capacitor power supply can deliver 12 volt DC and 100 mA current to power low current devices. It is provided with surge protection and is totally isolated from mains supply using two capacitors in the phase and neutral lines. So the connected device is safe even if the phase and neutral lines changes.
Transformer less power supply is used to reduce size and cost of electronic gadgets. Only low current devices can be run in transformer less power supply, since the output current is low. Unlike resistive type power supply, capacitive power supply isolates mains from the circuit and drops mains to low volt AC without generating heat. So power loss due to heat generation is negligible. The power supply works safely unless the capacitor burn out due to very high surge current. Costly equipments should not be connected to capacitive power supply.
Do not use this power supply for testing prototypes or as battery charger.
Do not construct this on Bread board. Use common PCB.