Speaking of LED lights - they clearly are ‘the future’ of holiday lighting, but they’ve always been too dim and the colors just a bit off. But that is changing. While many LED strings were still too dim for my tastes, I did find a set that was fantastic. The Sylvania (made by Inliten actually) C4 LED light strings that Wal-Mart and some Home Depots had are great. I have 8 of these 60 light strings around the property. They are some of the most brilliant LED Christmas lights I have seen. One reason they may be so bright is they have three power supplies along the string in small green plastic boxes while most LED strings only have one power supply in the plug. This lets them drive more powerful LEDs and reduce voltage drops in the long wires.

Sylvania’s white strings are also very bright, but are still ‘cool white’ not ’soft white’, which I expect to change in a year or two. But the color strings are fantastic, with five colors (Blue, Red, Green, Yellow, and Orange). But they aren’t cheap ($10 for 60 at Wal-Mart). Costco had a soft white LED string, though they weren’t very bright, but they looked more like normal incandescent lights than most white LED lights.

I expect my display will still be mostly incandescent lights, simply due to cost. It’ll be a few more years before LED strings are anywhere near as cheap as current incandescent strings. Plus, while they are looking better and better each year, they’ll never have the warmth of incandescent lights - which I think will always have a place in holiday displays.

So thanks for stopping by! Sorry I wasn’t able to pull things together this year. But I’m definitely going to do this, just for the fun of building and coding everything.

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In order to include X-10, I just need to include a routine to send out X-10 commands via the main controller. I’ll also have to include some type of throttling for the X-10 commands since they can’t react as fast as DMX. Perhaps only let the states flip or a dim sequence be sent every X seconds. Otherwise it would impact any other X-10 use in the house. We’ll see.

Regardless of the details, I may be able to utilize X-10 in a way that makes sense, even if just for a small part of the over all show.

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As I noted in an earlier post, the one area I’d rather get ‘off the shelf’ and avoid doing myself is the 120VAC dimming and switching. Sure, it can be done, but utilizing some off the shelf equipment for the line dimming and switching will not only make things safer, it’ll also allow more time to be spent on the control side of things. One of the big advantages of doing it yourself, however, is cost. Will off the shelf components be economical? Well, they can be if they come off your own shelf.

Some things in the display will require a simple on/off control. LED light strings don’t dim very well and they draw very little current. I might try putting together some other things using high brightness LEDs that blink/move, etc. So the power draw will be minimal and they will just need an on/off switch. Other loads might have motors or won’t look good if they’re dimmed, which sounds like a perfect job for a relay. I priced some DMX controllable relay packs, but they were expensive since they controlled big loads. I did, however, find a possible inexpensive do it yourself relay pack. Turns out I also have a potential low current relay pack sitting on my workbench.

I’ve always been interested in Home Automation and a while back I designed a circuit board with relays that could be controlled with X-10 commands. People used these to control irrigation systems via X-10 commands. Utilizing a small processor to do the heavy lifting, it was a simple design. Here’s one version with 8 relays on it.

While I was writing up my earlier post about the overall show and what I wanted to do with it, I realized I could modify these boards for DMX control fairly easily. All I have to do is put an RS-485 transceiver chip inside the housing of a DMX connector and run the digital side of the transceiver to the RJ-11 jack on the board and the hardware will work ‘as is’. All I need to do is modify the firmware to handle DMX instead of X-10 bit streams and probably boost the crystal speed up a bit since DMX operates at 250kbps.

I had created boards with 4, 8, and 16 relays on them so that should give me some flexibility. The only thing about these boards is they were designed for low voltage control. The relays they use are small and can only handle about 1 Amp of current at 120VAC when both sides are connected in parallel - about 120 Watts. The traces on the board can handle a few amps, so I’m going to see if I can find heftier relays with the same footprint.

Another option for relay control is a mix of home grown and commercial stuff. A few companies sell 8-Relay devices that are controlled by a separate set of switches. Check out the Elation SC8 system. The part of the system with the plugs has 8 relays inside that are controlled by a simple 9-conductor cable that connects to the controller.

The best part is you can buy the relay part of this system for $30-$40 to ‘expand’ an existing controller. So all I need is some type of RS-485 controller that can flip some digital I/O lines to control the relays. The perfect mix of pre-wired/commercial 120VAC control with some custom DMX control. Given the size of the relay part, I bet the board could easily be located inside the existing chassis with room to spare. Now, there are commercial DMX relay packs out there, but they can cost almost $250. So I’m hoping to take another board I designed which can receive RS-485 data and control an 8-bit data port. Depending how the relay pack is designed, I may need to add a driver circuit to fire the relay coils, but beyond that, it’ll be mostly software. Like the above relay boards, I can update the code to receive DMX and control the relays.

With any luck I can fit this board, two DMX connectors, and any additional driver circuitry into the existing relay chassis for an ultra compact 8-Relay DMX pack to control heavy duty lighting loads for a lot less than it would cost to buy (I’m shooting for about $50 per pack)

Hopefully that’ll help keep the costs down a bit. I’ll be spending enough on lights and such for the display anyway. If I can save money doing some stuff myself on the control side and using existing things I already have, all the better. I’ll be sure to keep you posted on the development of the firmware for these boards and how the final controllers turn out!

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Most people when they hear you want to network something instantly think ‘Ethernet‘. What many people don’t realize is that there are often better methods to network something in a local environment that doesn’t require Ethernet’s power and speed. Consider what kind of data will go across this network. We’ll be telling the nodes simple things like ‘Channel 4, Level X’ where X might be between 0 and 255. We aren’t transmitting War and Peace. If all we need to transmit are simple channel IDs and light levels, do we really need all the overhead of a normal TCP/IP packet?

Another common setup for controlling lights is the X-10 power line protocol. Signals are sent directly over the powerline to remote modules which can dim lights and turn electrical devices on and off. Many people don’t care for X-10 because they feel it is unstable and prone to false events (lights turning on by themselves, commands never reaching their destination, etc). If you buy a few X-10 modules and toss them in your home, you likely will see this type of behavior. Many modern appliances and electronics inject noise onto your home’s power grid. X-10 signals are also a form of ‘noise’ injected into the power lines of your home so you can see why extraneous noise could cause issues. However, by installing devices like an X-10 bridge, amplifier, and noise filters, you can have a VERY reliable X-10 setup in your home. I have all these devices and control a number of lights with X-10. I can’t recall the last time a light failed to go on when commanded or turned off on it’s own. So X-10 can be setup in a reliable way and could easily be used to control Christmas lights and other things. Another benefit is there’s no need to run control wires since the control signals travel over the powerline.

Why then, don’t we use it for the light display? In a word: latency. X-10 is a SLOW protocol. Bits are transmitted at the zero crossing of the AC power cycle which is 120 times a second (60 Hz and two zero crosses per wave cycle) for a data rate of 120bps. If we want to have the lights going on and off quickly and even flashing, X-10 can’t react fast enough to handle that. You also can only transmit commands one at a time and given the data rate, you couldn’t have lights appear to come on at the same time while still being separately addressable. So X-10 is out.

Wireless control is another possibility. However, the self contained modules tend to be a tad expensive and you also run the risk of interference from other devices on the common frequencies. While not running wires would be cool, there isn’t a pressing need to go wireless since we’ll already have extension cords running all around.

I have some experience in home automation design and will let you in on a secret. One of the most robust and simple signaling networks for controlling ‘devices’ is called RS-485. RS-485 is often mistaken as a protocol when, in fact, it is a signaling standard which various serial protocols are sent with. The standard lays out a signaling method ideal for harsh environments and for data that must travel significant distances without the use of repeaters. Ethernet is good over copper to around 300ft. RS-485 can be used up to 4000ft. It also is a much simpler network to wire. A simple twisted pair of wires is all you need. Instead of having to ‘home run’ the cables like Ethernet, you daisy chain the devices. This makes RS-485 ideal for industrial control networks where devices are spread across a factory floor and in our case where the nodes will be spread across the property. Simply run the twisted pair cable from device to device. Thus each ‘node’ simply needs an AC power feed and a twisted pair control wire from the nearest node.

[RS-485 Network Topology from lammertbies.com]

Another benefit of RS-485 is that it is used for serial protocols. Serial protocols are very easy to implement and significantly reduce the hardware and software overhead involved. Since we’ll have remote devices to control the lights, the simpler they are, the easier they’ll be to design and they’ll be less expensive. If the CPU in the remote device simply needs to receive bits and process the byte data, it can be a fairly lightweight CPU. Ethernet has much more overhead and requires more advanced hardware to process.

Many people don’t like RS-485 because they feel it is unreliable, though it is a defacto standard in industrial control where reliability is paramount. More often than not any instability is due to improper implementation. RS-485 signaling requires the nodes (up to 32) be daisy chained. You cannot have a star or tree topology in RS-485. Sounds pretty limiting. However, you can use devices like RS-485 hubs (see photo) which create individual daisy chained segments on an RS-485 network, allowing for more than 32 total devices and topologies like stars and trees. The network also must be properly terminated at each end of a segment to prevent signal reflections down long cable runs. If proper guidelines are followed in the implementation, RS-485 is a very robust and stable setup. Many of the commercial animated lighting control systems available from places like Light-O-Rama and Animated Lighting use RS-485 between the controller board and the remote light control boards. Much of my automation background involved RS-485 devices so it makes sense to use it in our display.

So we’re looking at an RS-485 network utilizing some type of serial protocol to control lights connected to remote ‘nodes’. Wouldn’t it be nice if someone had already done that?

Turns out, they have. For years, stage lighting systems have utilized a protocol called DMX which is sent via RS-485. The lighting control consoles send commands to remote light control boxes, often far away up on stage, to control the show lights and accessories. Simple twisted pair cable is used and since the remote nodes can be daisy chained, it makes setup a breeze. Imagine having 8 control boxes up in the rafters - it’s much easier to daisy chain them vs. home run them like Ethernet. By utilizing such an established protocol, not only can we rely on a wealth of knowledge out there, we can also leverage an entire markets worth of products (stage/DJ lighting) in our display. This makes using the DMX protocol very appealing.

So what exactly is DMX? It is a surprisingly simple protocol. Up to 512 ‘channels’ are set to a ‘brightness level’ between 0 and 255 where 0 is off and 255 is full on. The channel ‘brightness values’ are sent sequentially over and over. The first byte sent is Channel 1, the second Channel 2, etc. The lighting control packs and other devices are addressable where a 4 channel dimmer pack might be assigned address 008 so it’s channels become 8-11. DMX consoles send out all 512 ‘levels’ to the remote dimmer packs with the level values changing as needed. The dimmer packs ignore all the values except those sent for the pack’s known channels (8-11 in our example) The data is transmitted at 250kbps allowing lights to be ‘updated’ 44 times a second. This means you can easily ‘dim’ a light via DMX by lowering the light’s channel level from 255 to 0 over a period of time. The fast refresh rate means lights can be turned on and off very quickly.

This makes for an amazingly simple control mechanism. 512 bytes of brightness information are sent over and over in a loop with the values changing as needed. A remote node’s processor simply needs to receive the DMX data stream looking for the bytes that correspond to it’s assigned channel addresses and then adjust a channels output based on the received value. Any simple 8-bit microcontroller CPU can handle that. It also means the main controller will be simpler to design, but I’m getting ahead of myself.

So in a nutshell, the display will have a serious of remote ‘control nodes’ that will be controlled by sending ‘brightness levels’ out over a twisted pair cable using RS-485. The simplicity of the protocol means the hardware and software needed to control the lights will be less difficult and expensive to implement. By using an industry standard protocol, we also will be able to leverage and use devices already made for the stage lighting market where do-it-yourself isn’t feasible. The fast refresh rate of DMX means we can change the brightness levels of the lights very quickly allowing for eye catching show sequences.

Next we’ll talk about the types of remote node’s we might use in the display.

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To get things started, I want to talk about the electrical side of things.

To reduce the length of the extension cords, I want to have a modular control setup where I can have ‘nodes’ around the house to connect things to. These nodes will each be connected to one of probably four 20A branch circuits that will be hard wired outside and control circuitry inside will control the group of lights connected to it. I expect the house will have a variety of string lights, lit figures, maybe one of those tacky Happy Holidays signs, etc. We have a detached garage that is bound to have some lights on it as well, but it has a 20A circuit for the outside outlets which should be enough. I also expect to have a variety of things in the front yard as well as lights on bushes that are a fair distance from the house. I will probably put a number of those short heavily lit trees throughout the yard. This means whatever ‘nodes’ there are in the system will need to be ‘networked’ together.

I don’t expect any inductive loads (i.e. motors), but it’s a possibility, especially if I do a display for Halloween. I want to be able to dim the light strings as well as turn them on and off. I want to have the ability to flash the lights and possibly even have them twinkle. This requires a fairly fast switching method - a solid state switching method.

In order to switch the lights that quickly, you need a triac based control board. Triacs allow for very fast switching and dimming. The popular boards from places like Light-O-Rama and X-10 Lamp Modules use triacs. However these devices can only be used on resistive (incandescent lighting) loads. They are not designed to handle inductive loads. You can, however, get dimming systems that are designed to handle inductive loads utilizing zero-crossing circuitry (the triac is fired in sync with the zero cross and is fired long enough to handle the current lag of inductive loads) Many dimming modules used for stage lighting are designed to handle inductive loads.

To handle any type of inductive load (low voltage lighting, fixtures with motors), people often use relays. Relays are most often mechanical devices. A low voltage energizes a magnet coil which pulls a mechanical switch closed, completing the circuit. There are also solid state relays which use high current semiconductors to switch the loads on an off. Given their nature, relays can switch very high currents for their size and also can switch inductive loads as well as resistive loads. However, they are on/off. You can’t dim with a relay. X-10 Appliance Modules use a heavy duty relay, thus the loud ‘click’ when you turn them on and off.

One key difference between the two types of setups is boards with relays tend to be cheaper than dimmable boards with triacs, but not always.

Given the type of show I have in mind, I’ll have a number of loads that I want dimmed as well as loads that just turn on and off. Instead of using just one type of control method, I expect I’ll use both triac dimmers and relays.

I’ve have a healthy respect for electricity which can be the riskiest part of putting together a big holiday display. GFCI outlets and proper overcurrent protection are important. However, when putting together a DIY show, there are a lot of wires carrying 120V running around inside and outside the enclosures increasing the possibility of getting shocked. Point to point wiring is a common practice in DIY projects, but can be dicey when dealing with AC current. Another risk is a short causing 120VAC to feed back into the low voltage control side - a very dangerous situation. So one of my design requirements is to ensure that all AC switching is done via circuit board triac/relay based systems or opto-isolated module packs (see photo right). This also makes construction easier.

So what requirements are there so far?

• Try to use off-the-shelf, optoisolated modules or triac/relay based circuit board for 120VAC switching.
• Ability to handle resistive and inductive loads.
• Ability to dim some circuits (triac based). Relay control acceptable for some things.
• Fast response and switching time. Ability to switch in sub second cycles (twinkle effects, etc).
• Modular control system with networked ‘nodes’.
• GFCI protected circuits. 4-6 dedicated 20A branch circuits.
  

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I have a lot of experience with the WordPress blog software, so I decided to use that right away. Not only will it provide me with an easy to update website, but it also has a number of extension that will come in handy for the display. The fact that WordPress is becoming more of a CMS and less of a blog platform every day means I may be able to leverage things like user sessions and account for the custom software developed for the show. Only time will tell. The idea here is to leverage the site platform software as much as possible.

For now, the site is mainly for posting updates, pictures, and other information. Here’s how it is configured so far:

The site currently runs on a Dual Opteron server in a virtual linux partition with Apache, PHP, and MySQL.

As of this writing we are running WordPress 2.0.x with the following plugins:

• Adsense Deluxe - Plugin for easily integrating Google Adsense ads into the site. Gotta pay that bandwidth bill somehow!
• Bad Behavior - This is a must have plugin that stops spammers from accessing the site and wasting bandwidth and server resources. With spammers relying more and more on ‘botnets’ (groups of hacked machines) to spew spam faster and faster, it can really affect a server’s performance.
• FAQ - I expect to need a FAQ and while I could maintain a static page with the questions, a plugin makes it easier since it’ll handle all the formatting. The problem with this specific plugin is the author forbids any modifications even if you don’t redistribute the code which is silly. I may end up writing my own if it doesn’t fit my needs.
• Feedburner Feed Replacement - I’ve really come to like using FeedBurner for my RSS feeds, so this little plugin ensures anyone hitting the default WordPress RSS link goes directly to our FeedBurner Feed.
• Google Sitemaps - Great plugin to give Google additional information about your content and where to find it while your site is indexed as well as when new content is added.
• Google Sitemaps Tag Plugin - This plugin will add the tag URLs made possible by Ultimate Tag Warrior. This provides search engines more information about your site and posts.
  
• King Text Widget - A powerful sidebar widget allowing for custom JavaScript and HTML blocks.
• MarketingPop.us SEO - A plugin for Search Engine Optimization.
• Permalink Redirect - A plugin for Search Engine Optimization.
• Related Posts - An excellent plug that will list other posts related to the current one. Great way to find similar content as the number of posts increases.
• Secure Contact Form - Allows for an email contact form while stopping spammers cold.
• Sidebar Widgets - Allows for drag and drop setup of the sidebar. Excellent feature of WordPress.
• Smart Update Pinger - Ensures that we only ping sites like Technorati when new content is posted, not when content is edited (I tweak posts for spelling and formatting a lot)
• Sociable - A plugin that generates easy to use buttons for adding any content on this site to various social bookmarking and content sites like Digg, etc.
• Spam Karma 2 - By far THE most important plugin. This stops comment spammers COLD. You can’t run a WordPress blog without it. It also uses the excellent Akismet spam fighting network as part of the spam tests.
• Time Zone - WordPress doesn’t handle daylight savings well. This plugin fixes that.
• Ultimate Tag Warrior - This is the best tag plugin out there for attaching tags to content. It integrates with a few other plugins like Extended Archives, Google Sitemaps, etc. Allows users to find all posts tagged with a certain tag.
• WordPress Reports - Handy tool that grabs Google Analytics and Feedburner statistics and includes them in a WordPress administration tab.
• WP-Cache - All these plugins add code to the execution of WordPress which can cause significant load on a server during high traffic. WP-Cache will cache most WordPress content unless it changes, allowing for very fast response times and low server loads.
• WP Post Ratings - This plugin allows users to rate posts. It’s fun and also will allow for some theme changes I might implement (most popular content, etc)
• WPG2 - Plugin to integrate Gallery 2 with WordPress. Since I expect to have a LOT of pictures and videos on this site, I’m using Gallery 2 to organize them. This plugin makes it trivial to include Gallery pictures in posts and also shoehorns Gallery into WordPress maintaining the site’s look and feel.
• Xinha4WP - This is a plugin I wrote that allows you to use a very powerful WYSIWYG editor for creating posts.

As you can see, a LOT of addons make this site what it is. Of course no matter how well a site functions, it has to look good. I spent some time searching for a nice holiday theme and really like this one currently in use. The Vermilion Christmas theme from Amazing-Christmas-Ideas.com is a very nice theme that is also easy to modify and handled the addition of so many plugins with ease. I expect we’ll stick with this theme for a while. However, we likely will make some test runs of the equipment for other holidays like Halloween and maybe July 4th. We might switch to a more appropriate theme for those times. Any suggestions?

Over time the site will likely expand. I’m not 100% sure yet, but as we add custom code to the site, it may be easiest to do it as a WordPress plugin so we can use WordPress for user accounts, etc. It sure will help keep things integrated. More on that later.

Any thoughts on plugins that would be helpful? How does the site look so far? Suggestions for layout changes?

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