Électronique / Electronic
You know that an LED instantly lights when you turn it on. But you can also light it up gradually. In this project you'll be able to watch the LEDs slowly get brighter while you hold down the key. This circuit is called a Miller integrating circuit.
The output of this IC increases as its input increases. The integrating circuit increases the value of capacitor CA past the stated 100μF.
When you press the key, the capacitor charges slowly through resistor R and the LEDs becomes brighter. Setting the switch to position Β discharges the capacitor and turns the LEDs off.
Set the switch to position Β before completing the project to discharge the capacitor. Set the switch to position A and hold the key down to see LEDs 1, 2, and 3 become brighter. They reach maximum brightness in about 5 seconds. Set the switch to Β to discharge the capacitor and then hold down key to repeat the experiment.