555 Airplane PCB with Astable Dual LED Flashing ✈️

A simple airplane PCB to teach the principles of the 555 timer IC and astable mode using blinking LEDs.

Schematic

PCB Design

Bill of Materials

Component	Link
1x 3mm Red LED	Amazon Link
1x 3mm Green LED	Amazon Link
1x 3mm White LED	Amazon Link
NE555 IC	Amazon Link
10uF - 50V Electrolytic Capacitor	Amazon Link
3V Coin Cell Battery	Amazon Link
3V Coin Cell Battery Holder	Amazon Link
1.2k ohm Axial Resistor	Amazon Link
90 ohm Axial Resistor	Amazon Link
SPDT Slide Switch	Amazon Link
100k Potentiometer	Amazon Link

Design Analysis: Pulse Time and Duty Cycle Determination

The duty cycle of a circuit is ratio of the time the signal is active (high) to the total period of the signal. We want the duty cycle of this circuit to be close to 50% in order to get a congruent off/on blinking pattern form the airplane LEDs.

R1:R2 ratio predominately is what sets the duty cycle for the circuit

Output High Time Interval of Pulse

$$ t_h = ln(2) * (R_1 + R_2) * C $$

Output Low Time Interval of Pulse

$$ t_l = ln(2) * R_2 * C $$