One time constant, τ=RC= (3KΩ) (1000µF)=3 seconds. 5x3=15 seconds. So it takes the capacitor about 15 seconds to charge up to near 9 volts. This article explains how long it takes to charge a capacitor. This can be calculated using the RC time constant and waiting 5 time constants, which brings the capacitor to over 99% of the supply voltage.
After 5 time constants, the capacitor will charged to over 99% of the voltage that is supplying. After 5 time constants, for all extensive purposes, the capacitor will be charged up to very close to the supply voltage. A capacitor never charges fully to the maximum voltage of its supply voltage, but it gets very close.
It's common knowledge that after five time constants, the capacitor is regarded as fully charged, reaching a charge of around 99%. We can derive this information by applying the formulas above: From the formula of the time constant above, we can now formulate the equation for the capacitor charge time as follows: where: C C — Capacitance (farads).
Practically the capacitor can never be 100% charged as the flowing current gets smaller and smaller while reaching full charge, resulting in an exponential curve. This is why after a number of five multiples of the time constant, we regard the capacitor as fully charged. We'll explain the notion of time constant in the next section.
Charging a capacitor is not instantaneous. Therefore, calculations are taken in order to know when a capacitor will reach a certain voltage after a certain amount of time has elapsed. The time it takes for a capacitor to charge to 63% of the voltage that is charging it is equal to one time constant.
The capacitor charging cycle that a capacitor goes through is the cycle, or period of time, it takes for a capacitor to charge up to a certain charge at a certain given voltage. In this article, we will go over this capacitor charging cycle, including: