Simple Tranformerless Power supply


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 .

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How Capacitor functions as a Transformer? Design Note 42


CL-225-J
Transformer
is used to convert high volt AC to low volt AC (Step down) or low volt AC to high volt AC (Step up). So step-down transformer is generally used to convert 230 Volt AC to low volt AC which can be used to make a DC power supply after rectification and smoothing. But a Non polarized capacitor can act like a transformer to step down the high volt AC to low volt AC. Say, 230 V AC to 40 VAC. Let us see how the capacitor is doing this.
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