Update on my Arduino Random Lighting Controller

[RR_Mel]

I started out with a Arduino UNO using the 14 regular output ports to switch the cathode side of 14 LED randomly.  I use 40 to 70ma 12 volt Grain of Wheat bulbs in all of my structures because to me they look more realistic than LEDs for the 1950s era, for that I needed a high current driver.

 

I built a high current driver using an Arduino UNO extension board qand a pair of 500ma seven channel IC driver chips.  I originally went with a TD62304AP chip.  The TD62304AP has over doubled in cost to $4+ so I’m now using ULN2003AN chips also rated at 500ma for 50¢.  I have over 100 hours of operating time on several ULN2003AP chips with no failures.

 

I have increased the output ports from 14 to 20 and added a third seven channel driver chip to the expansion board.  Many of you use LED lighting so as long as you don’t exceed the UNOs output current rating you can drive one or two LEDs direct from the UNO ports easily, the published specs say 40ma per port but to be on the safe side I don’t exceed 20ma per port on any of my Arduinos.  By using a common ground I power my LEDs (lights) from a separate power source so that they don’t overload the Arduino built in regulator and keep the internal heat to minimum.

 

I also built up a test plug with 20 GOW bulbs and a test program for the Arduino to check extension board and driver chips.  The program will also test the Arduino outputs using LED test plugs.  I turn on all 20 ports for 5 seconds the sequence all 20 ports 1 second on with a ½ second gap.

 

 

 

 

If anyone is interested in more info send me a PM.  The Random Light Controller is rather inexpensive for LED users, the UNO can be found on eBay for under $5 and a 9 volt wallwart and you’re in business.  The high current expansion board with everything costs about $8.

 

 

 

Mel

 

 

My Model Railroad   

http://melvineperry.blogspot.com/

 

Bakersfield, California

 

I'm beginning to realize that aging is not for wimps.