So what's so special about the computer ?
- Nothing really, it runs Windows XP as an operating system
is the software to control the lights and music. The software
is free and user community of over 10,000 members exists at
The Logic Interface.
The interface I've used to control my lights I found at DoItYourSelfChristmas.com a simple expandable controller. There are many other interfaces that can be used from simple 8 channel ones to some very effective and clever dimming controllers, details of which can be found on the Do it yourself Christmas or Computer Christmas websites. For a description of the controller I've used, The Grinch, so named because that was a popular film out at the time the controller was designed, visit the do it yourself Christmas forums website.
The interface is made up of some shift registers with 16 outputs on each
chip. The devices can drive the opto-isolators directly so I don't need any
additional driver IC's. The power for the IC's is derived from a plug top
switch mode power supply producing the 5V. The outputs from each of the
shift registers is
then fed to some 9 way 'D' connectors, and RJ45 connectors. I have used
eight or twelve way alarm cable to connect between the patch panel and the opto-isolators as this is cheaper then CAT5 networking cable.
All this is housed in a rain proof box.
The opto-isolators as there name implies, isolate two
circuits from each other optically. The device acts as a
switch usually using a low voltage to turn on and off a high voltage
circuit. In this case we are using 5 volts to control the opto-isolator and switching either mains voltage (230 volts) or 24
volts. The opto-isolators were built onto strip board and
housed in plastic boxes of various sizes depending on how many channels
were being grouped together; 3 for the rope lights around the windows,
4 for the sets of mini trees, 2 boards with 8 on each for the conical tree etc.
The opto-isolators for the Merry Christmas & Happy New Year
signs drive the rope lights directly as each of the rope lights only
draw 70mA of current. Most of the boards have got triac's on
there outputs to drive higher current loads. Some of them are
for the LED lights which only draw 40mA of current and have IC bridge
rectifiers on them to provide the DC output required.
All these lights have to be powered somehow, some of the lights are powered by 240 Volts others are low voltage, typically 20 or 24 volts. Safety is very important especially with electricity outdoors. So all the mains connections including the plug in transformers for the low voltage lights are made inside rain proof plastic boxes and all three power feeds to these boxes are protected by RCD's (Residual Current Devices). You can't see them very easily in the picture as they are behind the timers, but rest assured, they're there, and tested!
Opto-isolators & RCD's
Baked Beans & Bulbs