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PlanetChristmas Do It Yourself Computerizing

How do I computerize... like what hardware do I need to build something from scratch?

There are several different techniques to connect the Christmas lights to your computer.

Perhaps the easiest and cheapest to implement is X-10 technology. You can buy the control modules at many stores and it's easy to set-up. The only drawback is it takes about two seconds to send a command, so if you want the lights to flash fast, this isn't the way to go.

Digital control is the most versatile method of controlling your lights. You can toggle lights on and off as fast as the computer can send an instruction... which is very fast. Your infrastructure setup will look like a star. The computer and high voltage electricity is at the center and everything radiates out from it. You can go through a lot of wire, but maintenance is easy.

How is the computer connected to the Christmas lights?

For starters, checkout D-Light or Light-O-Rama for easy to build kits and software packages.

Nuts and Volts magazine also has a couple of good articles.

Nuts and Volts November 2007 issue. Look for Holiday Lights.

Nuts and Volts December 2007 issue. Look for Vixen Lights the Way.

You might even consider some gear from the robotics world. Click here to see a great article about using USB relay ports to create a full holiday light system (include Microsoft source code examples.)

Here's how PlanetChristmas did it over 20 years ago with descriptions from the original website. The information is a bit dated but you can get a feel for the basics

PlanetChristmas uses boards from a company called CyberResearch (www.cyberresearch.com). They have a series of "Digital I/O Boards" which plug into a PC ISA slot so you can control the outside world. In 2002, a 24 I/O port board (part number CYDIO24) costs $47... a 192 port board (part number CYDIO192) costs $199. They also have 48 port and 96 port versions. Check them out on their internet page or order a catalog by calling 1-800-341-2525.

Each of these I/O lines is connected to a solid state relay (3-5VDC input, 120VAC output... they typically cost $5-$18 each depending on the current load (I use a 7 amp rated version from Magnecraft.)) Relay details can be found at Magnecraft. I buy the relays from Newark Electronics (1-800-463-9275) Delivery is usually 3-5 days from one of their warehouses. They take credit cards. I use Magnecraft part number W226R-7-5A1 which translates to Newark Catalog part number 23F5606... which is at the bottom left on page 808 of Newark's recent catalog. Pricing is based on volume, time of day, day of the month and fullness of the moon... in other words, whatever the salesman feels like when you call... I've never gotten any consistency.

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Each of the computer I/O lines (called a circuit) is connected to the appropriate strings in the yard. Most circuits are in groups of four or eight so chasing effects can be used. Here are some closeup pictures of a solid state relay box. To see a simple electrical schematic, click here.

Keep in mind, this isn't the only way to interface the computer digital output to the Christmas lights. Hill Robertson and his Computer Christmas website can also show you some great ways of doing this trick, also!

If building all this hardware makes you nervous, consider Light-O-Rama or D-Light.

The computer program was originally written in Microsoft's QBASIC and ran on DOS 6.22. A simple OUT(0) command is written to a port to toggle it on or off. See some Source Code below! I also use a short test program to easily command each circuit during initial setup... it's useful if you are trying to understand how to program the digital in/out board. Today, it is still a DOS based program, but I use POWERBASIC to compile it (mainly because it allows the program to be bigger than 64K in size) and run it in Windows 98 DOS mode.

The computer spends most of the time in a wait state, but the full light show takes about 15 minutes. In reality, the computer could be an old IBM PC (the original one) and the show would run fine.

How do I build a control box?

The key to connecting the computer to the light strings is the blue eight port switching boxes. This is where the 5VDC output of the computer is magically connected to the 120VAC required for the Christmas lights. The trick is to use solid state relays. Click here for a datasheet for these relays. The relays I use can be ordered from Newark Electronics.

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And here is a basic electrical schematic of the blue box above:

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There are eight identical circuits (of the above schematic.. see below) The brown perfboard on the right of the blue box above is where two of the 74LS08 IC chips are mounted... the 74LS08 is optional... it was added in the early days before the driver chips on the digital I/O boards got a nit more powerful. The yellow neon indicator lights seen at the top of the box are wired in parallel to the high voltage output which monitors when an individual circuit is on. The blue toggle switch on the left turns on the high voltage to the entire box and is monitored by the green indicator light next to the toggle switch. The fat, gray wire leaving the bottom of the box is the master cable controlling 8 high voltage circuits. The thin gray wire on the right of the box comes directly from the CyberResearch I/O card in the PC.

Here is the full schematic of one of the blue boxes used to switch the light circuits. The output of the digital I/O card in your computer feeds into the left side of this schematic, where the low voltage input of the 74LS08 input buffers are. The output of the buffers connect directly to the low voltage input side of the solid state relays. The high voltage output of the relays are terminated on terminal strips for easy connections to extension cords which feed the Christmas lights around the house.

Note that the 5 volts required for the 74LS08 IC's is gotten from the computer by tapping into one of the power cables that feed a floppy drive.

Here are the solid state relay boxes. Each blue box holds 8 solid state relays (called SSRs). The little perf board on the right inside each box is a simple TTL buffer to isolate and boost the voltage coming from the CyberResearch controlling card (again, these are optional.) Each relay box responds to one byte of information. Each byte contains 8 bits and each bit controls a relay. There are 2 to the eighth combinations or 255. So sending 255 to a box will turn on all the relays and sending a 0 will turn off all of the relays.

This is relay box number 28 (of 72 for 2002). Letters A-H correspond to the individual circuits. When I say turn on 28F, I know exactly which pilot light should come on. Here is the front of a relay box.

Below is looking into the top of a relay box (with the cover off) from the back.

Below is again looking at the top of a relay box from the front. I use Magnecraft Solid State Relays (those eight black blocks with the silver mounting tabs at the top of the above picture. Click here for the Magnecraft datasheet.

The yellow cord going out the right side is the primary AC power coming into the box. Each solid state relay has a 7 amp (at 120VAC) capacity (if they were heatsinked better.) In my layout, I'll run anywhere from 30-300 watts through one circuit.

How do you connect the circuit card to the solid state relay boxes?

There are up to three CyberResearch controlling cards inside the PC. Each card can control 192 relays. The card is connected via 50 conductor ribbon cables to a DB-15 plug panel where the relay boxes can connect to.

Below is the view of the back of the PC where the 50 conductor ribbon cable come out. There are three cards so there are three sets of cables (but this is an old picture and you can only see two.)

Below is the DB-15 plug panel. Each gray cable coming out the top goes to a relay box.

How did Chuck Smith do the original PlanetChristmas?

Where do you want to start? Chuck had PlanetChristmas all connected directly to one computer that controls everything.

So what is this thing to the left? There are 72 circuit boxes, each controls 8 circuits, giving the computer the ability to control 576 discrete circuits.