Inductor application circuit

An inductor, also called a coil, choke or reactor, is a passive two-terminal electrical component that stores electrical energy in a magnetic field when electric current flows through it.
Inductors are widely used in alternating current(AC) electronic equipment, particularly in radio equipment.

* This simulation only works while the mouse is pressed.
* This simulation is based on the actual circuit being operated(except the first circuit on the left). The power supply voltage was 3V, and the inductor was 330μH. The resistance for current regulation is 0Ω.

Slow light up circuit

At the moment of turn on the switch, a current flows through the inductor, causing a change in the magnetic field. The inductor generates back EMF(Electromotive force) against this change in magnetic field. In other words, the inductor acts like a resistance to the change in current. This resistance component is called 'inductive reactance'.
If the switch is pressed steadily, there is no further change in the magnetic field, so the resistance of the inductor gradually disappears, leaving only the role of the cable. so, the LED lights up.
In general circuits, the time intervals during which the LEDs light up are very short. Therefore, it is almost impossible to visually observe the process of lighting. The simulation above assumes an ideal situation.


A circuit that lights up for only a short time, when you turn on the switch

As soon as you close the switch, the inductor is like a very large resistor because of the EMF. Therefore, most of the current flows to the LEDs.
As time passes with the switch closed, the resistance component of the inductor decreases. So, most of the current flows through the inductor instead of the LED.
Note: This circuit is not a stable circuit. This is because when the resistance component of the inductor decreases, a very strong current flows through the inductor and it makes heat.


A circuit that lights up for only a short time whenever open the switch

When the switch is closed, a magnetic field is formed around the inductor.
If you open the switch after a while, an EMF is made in the inductor against the decrease in the magnetic field. The LED lights up with this EMF.
Note: The connection direction of LED is different from the previous one.