page_title: Capacitive power supply
section_title: Example
hierarchical_section_title: Capacitive power supply / Example
caption_attribution_description: English: Opened 230V 48x LED lamp; 48 LED, 3 W, E27 screw base. Integrated electronic circuit: Capacitive power supply Deutsch: Zerlegte LED-Lampe. Eingebaute Elektronik: Kondensatornetzteil Español: Fuente eléctrica integrado: Fuente capacitiva Français&#160;: Circuit électrique interne: Alimentation capacitive Català: Estabilitzador: Font capacitiva
context_page_description: A capacitive power supply, also called a capacitive dropper, is a type of power supply that uses the capacitive reactance of a capacitor to reduce the mains voltage to a lower voltage. There are two important limitations: First, the high withstanding voltage required of the capacitor, along with the high-capacitance required for a given output current, mean that this type of supply is only practical for low-power applications. The second is that due to the absence of electrical isolation between input and output, anything connected to the power supply must be reliably insulated so that it is not possible for a person to come into electrical contact with it.
  By the equation of state for capacitance, where, the current is limited to: 1 amp, per farad, per volt-rms, per radian. Or amps, per farad, per volt-rms, per hertz.
context_section_description: By changing the value of the example in the diagram by a capacitor with a value of 330 nF, we can provide a current of 20 mA. This way you can power up to 48 white LEDs (for example, 3.1 V/20 mA/20000 mcd) - that is provided connected in series. At 50 Hz, the 1.2 μF capacitor has a reactance of 2.653 kohm.  By Ohm's law, the current is limited to 240 V/2653 Ω = 90 mA, assuming that voltage and frequency remain constant. 
  LEDs are connected in parallel with the 10 μF electrolytic filter capacitor. The four branches with 12 LEDs consume about 20 mA each. The diodes limit the voltage to about 40 V per branch. Since, normally, the circuit is connected directly to the network without galvanic isolation, we need a residual-current circuit breaker  in any type of protection circuit used for this kind of LED light.
caption: A lamp that has 48 LEDs - 3 W/230 V
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