Hi,

My son asked me to build him an airport approach light system that contains 10 led's. My idea was to build something like this, a 555/4017 sequencer (http://www.talkingelectronics.com/projects/200TrCcts/101-200TrCcts.html#3A)

I'm stuck in figuring out the following;
1) how can i use a 12VDC power source
2) what do i need to do to change the sequence to two runs of all the light per second (this is the frequency of a real airport).

Hope you can help, as i'm new in 555 and 4017 IC's.

Thanks,
Alexander

 

It can already be 12 volts. The 470 ohm resistor should limit LED current. The chips can take 12 volts.

The 4017 triggers the transistor which holds the 555 until 3 seconds has elapsed determined by the 10K resistor and 100 uF capacitor. The interval between lights changing is the 4.7 uF and 10K ohm. The sizes determine the times so they can be changed. Try smaller capacitors and resistors for smaller intervals.

There are only 9 LED's, but maybe the 10th one on pin 11 can be used for one and charge the capacitor if you cut down the capacitance when the intervals are reduced. If you don't need the 3 second interval at all, the transistor part can be eliminated altogether.

 

Usually the approach landing light consist of two banks, one above the other that changes visibility depending on your approach angle.
Known as the PAPIS system.
Max.

 

Usually the approach landing light consist of two banks, one above the other that changes visibility depending on your approach angle.
Known as the PAPIS system.
Max.

They are referring to the "rabbit". That string of sequential strobes lined up with the runway's center line.

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Ken