Serial Port Holiday Light Flasher

In this post I will show you how to flash Christmas lights by the serial port. Now you can with Holiday232. This serial port can switch between 4 different lights by using 2 SPDT relays and both RTS and DTR of the relay. As you may be wondering when looking at the schematic why I’m using transistors and resistors. It is because the serial port voltage is higher than 12vdc. I don’t know what the forward voltage or current plus since there is a LED in series with the optocoupler.

The following things are required(for both DTR and RTS):

For 2-lights circuit you will need:

Wire color RJ45 screw termnalName(DB-9 Side)
Yellow and Black(3 and 6)Transmit and Receive. Tie together so it makes it easy to find the serial port(2 and 3)
White(7)DTR(4)
Brown(8)RTS(7)
Red and green(4 and 5)Ground(5)
Cisco console cable on screw terminals pinouts
Schmatic
Flashing green low voltage
Flashing low voltage green LEDs
YouTube video

Published by Justin Roeder

I am an electronics engineer and computer programmer that has autism. I learned by myself

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