It is very easy to convert 220 Volt AC to DC for powering electronic circuits. Any DC voltage from 3 volt to 36 volt can be generated from 220 volt AC using appropriate value of X rated capacitor and Zener diodes. The X rated capacitor drops 220 V AC to low volt AC. This can be rectified to DC by a Rectifier diode and smoothed by a Filter capacitor. By selecting a required value Zener, regulated DC can be obtained. But the only drawback of the Tranformerless power supply is its low current, so only light loads can be used. Here explains the design of a 4.7 Volt 4.6 Milli Ampere Tranformerless power supply to power PIR sensor .
1.X Rated capacitor – 100n ( 104 or 0.1 uF ) – 1
2. Resistor – 1 Meg Ohm ¼ watt – 1
3. 4.7 V / 5.1 V , 1 watt Zener Diode – 1
4. 1N 4007 Rectifier diode – 1
5. 33 uF 100 volt Electrolytic capacitor – 1
Triac BT 136 is used to drive lamp. Output from the Transformerless power supply is 4.7 volts and 3-4.6 mA current which is sufficient for the working of PIR sensor module and Triac.
The Current rating of different X rated capacitors and the Formula to calculate current
Caution – Extreme care is needed to construct the Tranformerless power supply since it carries Lethal voltage that can cause Shock. Do not touch or troubleshoot when connected to AC.
Always enclose the Tranformerless power supply inside a Shock proof cover such as Plastic cover or Heat shrink tube before testing.
If you are not experienced in handling high volt circuit, leave this alone to avoid the risk of shock hazard.