Resistance reduction principle of capacitance(I)

1. The current that can be supplied

This type of circuit is usually used to obtain a non isolated small current source at low cost. Its output voltage can usually range from several volts to three tens of volts, depending on the zener voltage regulator used. The magnitude of the current can be proportional to the capacity of the current limiting capacitor. When using half wave rectification, the average current value of each microcapacitor is: (international standard unit).

I (AV) =0.44*V/Zc=0.44*220*2*Pi*f*C

=0.44*220*2*3.14*50*C=30000C

=30000*0.000001=0.03A=30mA

0.44: average coefficient of half wave rectifying

F: power frequency unit HZ;

C: capacitive capacity unit F Fala;

V: power voltage per unit volt V;

Zc=2*Pi*f*C: impedance unit ohm.

If full wave rectification is used, double current (average) can be obtained:

I (AV) =0.89*V/Zc=0.89*220*2*Pi*f*C

=0.89*220*2*3.14*50*C=60000C

=60000*0.000001=0.06A=60mA

Generally, the full wave rectification of such circuits is slightly larger.