Z80 Space-Time Productions Single Board Computer
Computer Controlling Christmas Light Displays
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The Idea
Probably everyone with an email account gets "Contagious Viral Video" emails from time to time. You know the subject line:
You just gotta see this! In December 2005, one such video made the rounds. It just so happened to be one of
the many houses who bought computer controllers for their Christmas lights outside the house. The music was sent by a small
FM transmitter to the passing cars so they could watch the Christmas lights flashing in sync with "Wizards of Winter". Well
it obviously attracted the attention of one of the beer manufacturers as well, and became their TV commercial for the holiday
season. [I just hope that guy got paid something for their multi-million dollar promotion]. I decided that my small Z-80 computer had enough I/O mapping to do a pretty healthy job sequencing lights. I had already been doing some of this with a panel I had hooked up to the unit. Using ULN2803 drivers to run the lamps, I had written a few short programs that simply ran a time delay between incrementing its way through a bit table for turning on and off various lamps in various patterns. I got a little ribbing for it, and a lot of interested looks, but the idea had never progressed to sequencing whole strings of Christmas lights outside my house. After researching this phenomena, I found out there are a great number of people who design, build and sell computer controllers for Christmas lights. Some are very hi-tech, some are so-so. A few of the home-brew sites I saw were so embarrassing I am surprised they bothered to take pictures of their various rat's nests and post the to the Internet. I keep waiting to hear on national news where one of these kluge jobs burned their house to the ground. AC power is not something to be kluged together, you must have a healthy respect for it and neat wiring jobs, or you will have a big, big problem down the road. One effect I noted that I particularly liked was the idea of having Christmas tree(s) that were made up of individually controlled strands of light going from the bottom to the top. These trees could be "rotated" in software by sequencing the strings in order, and gives a very appealing look. An associated effect that I liked was to have a series of lighted stars leading up to the main star at the top of a tree, so it appears a shooting star is hitting the tree top and causing the whole tree to burst into light. Very very nice. Construction of the Displays Here is the diagram for the "Great" Christmas tree.
This are going to consist of:
The 2x4 base should be cut on 11 degree angles, and attached together to form a chord-angle circle. This will also give the 22.5 degree points where the light strands will be hooked so that they will be equadistantly placed around the circle. Each place with pair two light strands together Red/Green - Blue/White. Each strand starts at the base, loop over the top of the pole and end on the base opposite where it starts. Eight quad outlet boxes will allow hook up so that each box carries 4 "Hots" and 2 "Neutrals". This gives individual control over each segment and each color. The Electronics It is a very simple matter to turn light strings off and on in various sequences. All it takes is a little tiny bit of assembly language software, and some I/O port latch IC's. But this gets boring after a while. Most of the displays I have seen have some good effects with them. Fading the lights on and off gives a nice subtle effect over the standard On/Off. Also, with this type of control you can use the music audio level to modulate the lamp intensity. These effects add a warm fuzzy to the overall light sequences that make the display seem more friendly to those watching. Here's a board that I designed for controlling power triacs using the MOC3063 and L2008L8 8Amp TO-220 Triac modules. It's designed to work in conjunction with the Digital Output Board that I designed as well. Be sure to look over at the Papilio section of my site to see these boards and the Papilio controller.
This board is easily controlled by a Z80 system, or Arduino or Papilio FPGA board. There are no on-board limiting resistors for the MOC3063 Opto Isolated Triac, so your interface will need to include some, probably in the 330 ohm range, depending on your switching voltage. The reason for this is that the Digital Output Board that I designed already has them in place, so there is no need to have them on a limited size board of this nature. Also, please note the fuse and AC voltage warnings throughout. This page created February 21, 2006.
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