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Project Notes

#552 Aircraft Navigation Lights

Demonstrating a simple aircraft navigation beacon sequence implemented with a couple of 555 timers.

Build

Here’s a quick demo..

clip

Notes

I came across this Aircraft Navigation Beacon circuit and thought it was an interesting trick to achieve with some 555 timers. It runs white LED beacons that flash twice then delay 2 seconds before repeating.

These apparently simulate anti-collision strobe lights for aircraft.

After a few tweaks found the circuit works reasonably well, however it is very touchy and component values need to be carefully selected in order ot get the timing right.

To show the circuit off a littly better, I fashioned a little aeroplane model from some popsicle sticks that sits proudly atop a 9V battery.

Construction

The circuit uses two 555 timers running as astable oscillators.

The first 555 timer provides the basic on/off cycle, with a very low duty cycle since D1 diode steering selects a different resistor for charge/discharge:

The second 555 timer provides the oscillator for the LEDs.

  • frequency is governed by R3/C2 (1MΩ, 220nF) nominally 3.2Hz
  • is only enabled (vai pin 4) when the first 555 timer output is high

Breadboard

Schematic

Testing on a breadboard:

AircraftNavigationLights_bb_build

In order to ensure two LED flashes each cycle, the on time of the first timer must be just right for the frequency of the second timer. I fiddled around with component values a bit to get it “close”. Still not perfect; here’s a scope trace showing how my “on time” is just a little bit too short to get two equal flashes each cycle:

  • CH1 (Yellow) - timer 1 output
  • CH2 (Blue) - timer 2 output

scope

Credits and References

About LEAP#552 LED555 Timer
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is my personal collection of electronics projects, usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting (IMHO!).

The projects are usually inspired by things found wild on the net, or ideas from the sources such as:

Feel free to borrow liberally, and if you spot any issues do let me know. See the individual projects for credits where due. There are even now a few projects contributed by others - send your own over in a pull request if you would also like to add to this collection.