Capacitor charge and discharge through resistor protected LEDs Circuit

The capacitor in the schematic diagram below, will charge up to 6-7 volts when the left button is pressed. And discharge to 2-3V when the right button is pressed for some time.

Capacitor charge and discharge through resistor and LED circuit schematic diagram by electronzap electronzapdotcom
Capacitor charge and discharge through resistor and LED circuit schematic diagram by electronzap electronzapdotcom

The LED in series with the switch being pressed will light up while current flows.

The resistor will determine how much current flows. More current equals a brighter LED, but for a shorter time. That is due to the capacitor charging or discharging faster.

The LEDs drop about 2-3V, depending in their color. They need that much voltage to conduct, and the get rid of that much voltage as far as series components are concerned. So, 2-3V of the supply voltage, won’t make it to the capacitor. And the capacitor won’t be able to move current through an LED, when it drops to 2-3V.

Real voltage drop for the LEDs will actually be closer to a 1.5-2.5V, because a small amount of current will flow at voltages slightly lower than the forward voltage of the LED. The forward voltage is measured at a higher current than that which can trickle a leakage current, and produce a dim LED light. But, that leakage current is still enough to change the capacitor voltage.

Larger value capacitors will take longer to charge. The LED will take longer to dim than with a lower value capacitor.

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