It's All About Electronics

May 17, 2018

Capacitor Charging and Discharging Part 1

A capacitor charging and discharging phenomenon is one of the most important factor in Analog electronics. There are many electronics circuits in which capacitor charging and discharging plays a very important role. It is also one of the most confusing concept in electronics. In this video we will discuss capacitor charging and discharging phenomenon for four different situation:

1.Time enough to fully charge and fully discharge.

2.Time enough to fully charge but not fully discharge.

3.No time to fully charge but time to fully discharge.

4.No time to fully charge or even fully discharge.

This is a basic R-C series circuit. Circuit consists of a DC voltage source, a capacitor and a resistor. Now let’s start circuit analysis. It’s a series circuit. So, the common element which is same for all three components is current. Same current is flowing through all the three components. This current is not constant, it is varying with time means time dependent. So, our time varying current will be i(t). Capacitor voltage is Vc.

Vc=V(1 - e^(-t/RC))

This is a source free R-C series circuit. Circuit consists of a capacitor and a resistor. Now let’s start circuit analysis. It’s a series circuit. Lets assume capacitor has initial voltage V. So, the common element which is same for all components is current. Same current is flowing through all the components. Now, this current is not constant, it is varying with time means time dependent. So, our time varying current will be i(t). Capacitor voltage is Vc.

Vc=Ve^(-t/RC)

Input and Output waveform

Time enough to fully charge and fully discharge