Capacitor charging circuit

From Knowledge Kitchen
Jump to navigation Jump to search


In the following circuit, when the button is held down, current will flow until the capacitor is fully charged. Once the capacitor has fully charged (to the same voltage as the power supply), the current will stop flowing.

To illustrate this, we have added an LED. The LED will turn on at first as current is flowing, but will quickly turn off once the capacitor is fully charged.

Circuit diagram for charging capacitor


Discharging the capacitor

In order to test this circuit more than once, the capacitor must be manually discharged after each charge. To discharge a capacitor, simply connects its legs together with a screwdriver or piece of wire. This allows the charge to flow from its positive side to its negative side thereby neutralizing its charge.

For a more visual discharge of the capacitor, pull it out of the circuit, and touch the capacitor's legs to the legs of an LED. Touch the capacitor's long leg (positive) to the LED's short leg (negative), and vice versa.

Discharging a capacitor with an LED


Questions

  1. How does adding a 2.2kΩ resistor between the pushbutton and the capacitor affect the capacitor's charging behavior?


What links here