Electronic – What resistors and capacitors will I need

capacitorledresistors

I have 4 LEDs that are rated for 3v-3.2v 20mA. Each LED will be wired in Parallel to a 5v power supply.

When power is applied to the circuit, I would like each LED to turn on with a delay.

The first LED with a 0.1 second delay, the second with 0.2 second delay, the third with 0.3 second delay, and the 4th with 0.4 second delay.

What capacitors, and resistors, will I need to make this possible?

LED gradually lighting up over time is fine.

Best Answer

In this circuit the subsequent LED won't start its RC timer until the previous LED lights, so all time constants can be the same (0.1 sec, approx 1M and 0.1uF, adjust as necessary). The buffer needs to be non-inverting (could be a quad OR or AND) and capable of supplying the LED current (4 * about 5mA each). The LEDs will snap on at even intervals, not fade in.

schematic

simulate this circuit – Schematic created using CircuitLab