Continuing with where we left off...

As recited in the previous iteration of this series, capacitors are passive elements that have, as one of Its features, the capacity to storage energy or "make" the impression that they are storaging It, while they're only disipating the potential difference through them in a slower way. Is in this point that concepts like charge and discharge times come to our vocabulary, where the first Is simply the time that It takes for the voltage to go to Its max point (Determined by what provides tension to the condenser) in the capacitor and discharge times is just the opposite. Well, we promised to show ways in how you can calculate your capacitors for increase of the time It takes for them to charge or discharge, well, Let's get started with It.

Charge Process:

To understand this part of the overall process better, we had chosen an RC circuit that has the components in the figure. As we notice, there's a switch before the RC combination, with two positions, in the first position (A) It's obvious that current, and most importantly voltage, is gonna pass through that point and to the capacitor. Now, considering that this switch has been in B for a long time and just now has passed to A, you might think that capacitor now displays the full voltage It can display (Being that of the source minus the electrical tension difference with the Resistor), though It's not like that. this element opposes strongly the abrupt change in the amount of voltage that It's now being given, and for It to display the same exact tension as the source, It has to follow a certain concept, this being the time constant, or Tao, in which the capacitor voltage rises from 0 to a 63.2% of the source's present voltage. The way to determine this variable is easy, It's just the product between the resistor and the capacitor in the circuit (T=R*C). Then, when 5 of these time constants had been surpassed, It's safe to say that the capacitor has risen to 99.3%.

Well, with this given, It's not rocket science the fact that to increase the time that a capacitor lasts to charge itself to Its very max, you have to increase either the value of the resistor or the filter involved.

Now, If you want to know the voltage of the capacitor at any determinated time, you just have to use the next equation:

Vc = E + ( Vo - E) x e^(-T/ t)

Where we already know that E is the supply voltage and that T represents the time constant, though we find a new element, this being Vo, the initial condenser voltage, which can easily be assumed in most cases as 0 or the tension that the circuit had in the previous position of the switch.

Now, passing to the Discharge Time.

Discharge Time:

Let's say that the switch in the figure has been brought back to B point. This means that tension is no longer being proportioned from the source to the rest of the elements (Being that the source is in a shortcircuit). Again, showcasing the capacitor feature of not letting any abrupt change occur in Its voltage, the latter won't decrease that easily, passing through the same period of time to fully lose Its electrical tension difference. We use the same variable, the time constant, in which If 5 time constants are surpassed, the capacitor will be fully discharged. If we want to really know the voltage during this period, we just have to use the equation:

Vc = Vo x e^(-t / T)

Which is simply the same equation as during the charge time, though we just assume that since no voltage is being provided by the source anymore, Its value is 0.

In this way, we can conclude that to know what capacitor we should use for a determined charge and discharge we just have to figure out the time constant for our desired purpose, where If we increase or decrease the capacitance in the capacitor or the resistance value from the resistor we can easily do the same with the times of voltage increment to the max/min values of this device.

Being said this, we can finally past to the third part of this series of articles, which will be focused solely in the different types of capacitors we can find and their differences.