How Computer Controlled Animated Lighting Works

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Overview

This hobby uses a combination of computer software, various kinds of wiring both for computer control and electrical power, electronic 'controllers,' relays, lights of various kinds and a myriad of hooks, tape, plastic and metal pipe, plastic "zip ties" and other methods to fasten and hang the lights on the house, bushes and trees. Most of the supplies can be purchased at local hardware or home improvement stores while the electronic controllers and other specific lighting components are usually purchased from electronic parts supply stores and other DIY lighting hobbyists' online stores.

Software

You'll install software onto your computer and use it to design a "sequence" of lighting effects. Many of the most popular software tools are free while some are fee-based. Most use the Windows operating system but other options are available.

Lighting Effects

The effects you'll use might include simple on/off, or pulsating on/off, or gradual brightening (called ramp up) or gradual dimming (ramp down). And if you like, the software also allows you to make these effects occur in time to a song or other piece of music you've chosen. Music is an important element of lighting sequences because without it, lights can appear to be random and uncoordinated; it's the music that ties it all together. For example, if your chosen song has a nice drum beat, maybe you want some lights to blink in time with the beat. Or maybe you want the lights to gradually get brighter as the music gets louder or maybe dim the lights down when the music is soft. The point is that you can control exactly when you want the effects to occur, even down to fractions of a second.

How many lights can I control?

The software allows you to separately control many, many strings of lights or even individual lights if you want. Each string or individual light that you want to control is called a "channel." So your sequence of effects might include dozens of strings of lights (dozens of channels), each of which you can control independently from all the others. So you get to decide what lights to turn on/off, when and how bright you want them to be. The software gives you total control. The software also provides normal editing capabilities such as changing the settings and saving them later. It also allows you to group several sequences together to make a longer program or "show." And once you have designed your "show" the software can also be used to schedule what days and times you want your show to start and stop. Pretty cool stuff!

How does the computer control the lights?

When you "play" your sequence (your show program) on your computer, the software causes your computer to send out special signals to other electronic devices that you build that are out in the yard. These devices are called "controllers" and the lights are connected to the controllers. Some controllers can handle only 8 or fewer "channels" of lights while others can handle many thousands of channels. The lights are plugged into the controllers and the controllers are plugged into electrical power. When the controller gets a control signal from the computer to turn on a certain channel, the controller's electronics figure out which channel it is and then allows electricity to go to that channel, illuminating that channel's lights. In the examples below, an "all in one controller" is shown. It's "all in one" because it has its own power supply and can also power the lights directly. Here's an example:
1-all-in-one.png
Often you can interconnect multiple smaller controllers together to control even more channels. In a way, it's like plugging one extension cord into another, and another, etc. The process of interconnecting controllers is called "daisy-chaining."
2-daisy chain.png

How does the computer connect to the controllers?

Computers and controllers are usually physically connected to one another by wire, often using inexpensive everyday network cabling (called cat5 cable). More often than not, there's an USB or other type of adapter/dongle that plugs into the computer that facilitates the electrical connection between the computer and the physical wiring. The electrical mechanisms that computers and controllers use to talk to one another are called serial RS-232, serial RS-485, and Ethernet (the same mechanism used for computer networking). With regard to speed, think of RS-232 in terms of tens of thousands of bytes per second, RS-485 in the hundreds of thousands and Ethernet in the millions of bytes per second. On top of the electrical mechanism is a "language" that the computers and controllers speak. Another word for this language is "protocol" and popular protocols are Renard, DMX, and E1.31. The Renard protocol can easily run on top of RS-232 or RS-485, DMX can run on top of RS-485 and Ethernet, and E1.31 is Ethernet only. And with some trickery, Renard can also run on top of Ethernet using another electronic gizmo called an "Ethernet bridge." Sometimes, instead of using cat5 cabling, some users replace the physical wiring by using wireless communication and various combinations of small transmitter/receiver setups. Some of these wireless systems can work upwards of 1/4 mile away.

How do I decide whether to use RS-232, RS-485 or Ethernet?

This is determined by the kind of lights and controller(s) you select and the protocol method you choose for your computer to control them. The software has settings that you simply choose and those settings are saved automatically along with the sequences you design. Then when you assemble your controllers, you'll load the proper settings into them to match. If you later decide to change your computer's settings, you just change the controller settings to match. It's easy to do. The "protocol" is the "language" that the computer and controllers use to talk to one another, and it's vitally important that everything be using the same protocol or you'll encounter communication problems. For example, if you had 5 people in a room and each spoke a different language, it would be difficult for them to understand one another. So they all must speak the same language (i.e. "protocol") for communication to work.
One extremely important thing for beginners to understand is that in the DIY world, various kinds of connectors can be used for many different things. For example, the "network jack" on the back of your computer is designed to be connected only to network-type devices such as switches and routers. In the DIY world, for convenience and to reduce cost, the same kinds of jacks, plugs and wires may be used for other things such as serial communication or voltage connections to external light control devices. As such, just because a jack or plug "looks" like a network connector and the same cable types will plug into them, BE CAREFUL because they may not be for a network at all and connecting two devices of the wrong type can damage one or both units!

How do the viewers hear my music?

While your computer is playing the sequence the computer's sound card will simultaneously be playing the music to keep the music and computer control commands in sync with one another. Some hobbyists use small amplifiers and put speakers outdoors so visitors can hear the music, but sometimes outdoor speakers create issues with neighboring homeowners. So most DIY'ers connect a small, low-power FM transmitter to their computer's sound jack to transmit the music to visitors' car radios so they can listen in the comfort and privacy of their vehicles. Low-power FM transmitters are not expensive -- anywhere from $25-$100 -- but whether you use outdoor speakers or an FM transmitter, the synchronized audio absolutely makes the difference between a truly entertaining "show" and what looks like a yard full of randomly blinking lights.

What are these SSR things I read about?

An SSR is short for "solid state relay" and it's just a device to safely control powerful electrical current by computer control. All-in-one controllers have SSRs built in so that all you have to do is plug the controller into main power and then plug the lights directly into the controller. However, some controllers use external SSRs which are not inside the controller box. Most SSRs are designed to be 4-channel units; 4 channels equates to 4 "circuits." Using remote SSRs sometimes involves a little more wiring, but it can result in a more convenient way to lay out your show. Here are a couple examples:
3-remote ssrs.png
Daisy-chaining is of course still possible!
4-daisy chain remote ssrs.png

Overview

In a nutshell, the computer plays a "sequence" that you created, it sends control signals out a wire to the controllers, the controllers decode the signals and turn on/off the appropriate lights, and all the while your viewers are listening to the music you've chosen and watching your lights dance with looks of wonder and amazement. And that's how computer animated lighting works.