I have finally come up with a flashing tower beacon driver that looks very realistic. I'm using an Arduino NANO with a NPN Darlington MPSA13 transistor to drive a 2mm 12 volt Grain of Wheat bulb. The bulb draws 70ma at 12 volts and as normal I'm running the bulb at about 70% for max realism and longer bulb life. The MPSA13 has 500ma sinking capacity so it will easily handle the bulb current.
The MPSA13 drops the voltage by .7 volts so I'm actually operating the NANO at 9¼ volts to achieve the 8½ volts to the bulb.
I couldn't find any premade NANO expansion boards so I cut up some 18 x 24 hole perfboards. I can get three NANO expansion boards from one perfboard.
This is a drawing of the Mel NANO expansion board.
Here is a 30 second video of the flashing beacon with my Arduino NANO test socket. I prewired a Mel test socket with seven 12 volt Grain of Wheat bulbs. I don't plan on using more than 7 high current outputs from a NANO.
Here it is flashing the tower beacon.
The NANO Sketch (Program) is below, a simple copy & Paste to the Arduino IDE should work OK.
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/*
Fade
This example shows
how to fade an LED on pin 3
using the
analogWrite() function.
This example code is
in the public domain.
More info:
http://www.ardumotive.com/how-to-fade-an-led-en.html
*/
int led = 3;
// the pin that the LED is attached to
int brightness = 0;
// how bright the LED is
int fadeAmount = 5;
// how many points to fade the LED by
// the setup routine runs once when you press reset:
void setup() {
// declare pin 3 to
be an output:
pinMode(led,
OUTPUT);
}
// the loop routine runs over and over again forever:
void loop() {
// set the
brightness of pin 3:
analogWrite(led,
brightness);
// change the
brightness for next time through the loop:
brightness =
brightness + fadeAmount;
// reverse the
direction of the fading at the ends of the fade:
if (brightness == 0
|| brightness == 255) {
fadeAmount =
-fadeAmount ;
}
// wait for 30
milliseconds to see the dimming effect
delay(30);
}
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