Integrating circuit LM324
You'd think that any LED instantly gives a flash when you switch it ON. But by applying some knowledge of electronics, you can light it up gradu-a-lly...
It's exciting to see an LED getting brighter slowly while holding down the key, and you're going to feel that excitement in this project!
The circuit that realizes this interesting performance is called Miller integrating circuit. Capacitor C1 shows a very high nominal value because of the function of IC 324.
When you press S1 ON, the capacitor is charged slowly through resistor RA and the LED becomes bright slowly. S2 is used to discharge the electric charge stored in the capacitor.
To use this project, press S2 after switching power ON to discharge the electric charge from capacitor, then keep holding down S1, LED becomes brighter little by little. It reaches the maximum brightness in about five seconds. Press S2 to discharge capacitor and then hold down S1 to repeat the experiment.