31 December 2013

Customer Question: Should I use a centralized or de-centralized controller for an element?

HolidayCoro sales/support often sees common, open-ended questions from our customers and here on our blog we post detailed responses publicly so that other people will be able to learn from the decision making process we use to answer these questions.

Today's question is:  "I am making 16 pyramids and would like to light them up using 3 or 4 Basic Rectangle RGB LED Waterproof Module per pyramid.  The pyramids will be in the front yard each about a yard apart.  My Question - should I buy 16x Item #30 Basic 3 Channel RGB DMX Controller or should I buy 2x Item #24 Basic RGB 27 Channel DMX Controller.  Is there any advantage to either in this situation?"

For this given project it has already been determined that basic or dumb RGB lights should be used as opposed to pixels and this is often the case when an element doesn't need the control that pixels offer or when there are larger distances between elements.  So the question becomes - should the basic RGB DMX controller be centralized in the form of a 27 channel (9 RGB outputs) DMX controller or individual 3 channel (1 RGB output) DMX controller in each element?  The issue comes down mainly to two factors - cost and complexity:

  • Cost - The number of RGB lights won't change between the two methods, so we'll exclude that from the calculations, though what does mainly matter are wiring, power supplies, controllers.  Also, we need to determine he power consumption of the RGB Modules, which in this case consume about 100ma (1/10th of an amp) at 12v DC - or 16 elements x 4 modules is 6.4 amps total.  So, we'll take the number of individual elements here - 16 and do some comparison math with the two options: 
    • Centralized - This method allows us to have one (or two in this case) centralized controllers - the costs involved are:
      • $114 ($57 x 2) - 27 Channel DMX controllers
      • $26 ($13 x 2) - 45w (3.75amps at 12v) power supply.  This solution would power each 27 channel controller with a single power supply.  It's a little tight on the power at 3.2 amps total per controller (32 modules per controller) but it should work.
      • $20 ($10 x 2) - Waterproof housing.  The 27 channel controller isn't waterproof, so you'll need a waterproof/resistant housing and this varies by region, water/snow conditions and budget.
      • $20 (100ft @ $.10 per foot x 2) - CAT5 wiring.  You'll need to get the output of the controller out to the individual elements and CAT5 would be a good solution here as the current consumption of the lights is below the current carying ability of CAT5 at a bout 3 to 4 amps and it has 8 wires, so you could double up each wire for the 4 wires required for RGB lights.
      • ~$180 - Total
    • De-Centralized - This method allows us to have an individual, 3 channel DMX controllers in each element - the costs involved are:
Of course there are other minor costs - shrink wrap, solder, tools, shipping, etc and we've not included those in the calculations above.  So, on the surface, they look pretty much about the same from a cost basis, so let's take a closer look and consider all the other factors:
  • Complexity
    • Interconnections - Left out from above on both are how you'll interconnect the wiring from the element to the controllers.  
      • Centralized - With the centralized solution, you could solder the CAT5 wire directly to the lights in the element and then have elements with 20, 15, 10 and 5 ft lengths of cable coming off them and then you'd fish that wire into the controller case and screw it down to the terminals on the controller.  The problems with this solution are that it makes future adjustments in length complicated since you've already set the length of the cable from the element to the controller when you built the element.  Additionally, you'll have to deal with elements that have attached wire and then manually wire up each element to the controller, adding to your display setup time.  An additional down side to this method is that you also have more wire spread out over your display which can present safety/tripping hazards.  The upside to this method is that it doesn't really require any additional connectors - just tin the wires where they go into the controller screw terminals.
      • De-Centralized - If you've placed the individual CAT5 controllers in each element, that means that you can simply attach a 3 way splitter to each CAT5 plug, then plug in the necessary CAT5 cable between each element (5ft lengths in this case) in a daisy chain arrangement.  Then you just build a power injector for each of the two bands of 8 elements and this allows you to run the power and the DMX signal from one element to the next.  The amount of wire is limited as it only goes from one element to the next.  The down side is that you need to ensure that you control water ingress in to the CAT5 connectors and use a corrosion control spray - usually mounting the controller up-side down under the element would be more than sufficient to manage water ingress.  The real beauty of the Power+DMX over CAT system is that you can assembly your display quickly just by plugging into each element to the element next to it.

27 December 2013

Factors to Consider When Designing an RGB Pixel Matrix

Over the years we at HolidayCoro have been asked why we only sell a single pixel matrix product - our 18" x 24" pixel with either 150 or 162 pixels.  Well, actually, we've produced a fair number of custom matrix based panel items for customers over the years and the main reason we don't offer all these variations for sale is because each project is so different.  The article hopes to provide information on factors that we consider when working with customers on designing a pixel matrix and hopefully this will help those building their own or working with us to custom produce one.
  • What exactly is the purpose of the pixel matrix?
    • Is this matrix intended to be dense enough that viewers will be able to see objects scrolling or displayed on it such as text, icons or logos?  
    • What is the viewing distance from the matrix to the viewer?  If you've ever looked at a big screen TV up close, you can understand the relationship the size of the pixels (lights) have to the distance they are being viewed from.
    • What is the viewing angle?  A curve pixel panel (such as a pixel megatree) can look odd if all the pixels in the matrix are not visible to the viewer.
    • What is the shape of the matrix?  Is the matrix a cone, in the case of a pixel megatree, where the pixels at the top are in a much higher density than those at the bottom of the tree?  Is the matrix cylindrical?  flat? concave or convex?  All these designs have an effect on the final output, pixel density and mounting methods.
  • Technical factors to consider include:
    • Number of pixels - This is an important factor to consider and the number shouldn't be random - it should be based on the design requirements.  Look closely at how many pixels you'll need and their spacing from each other.  If needed, build a sample mock-up and view it from the distance and angle you expect your viewer to view it from. 
    • Pixel height and width - Also consider how many pixels you may need to display certain items such as a text font which often require a 5x8 pattern.  Again, keep in mind that you will also need to have the pixels close enough that the human eye can make out the pattern - just because it might look good in the sequencing software doesn't mean that will translate into the real world.  
    • Multi-Panel Alignment - If the matrix will be comprised of several panels, be sure to carefully consider the spacing within a panel and how it relates to the spacing induced between two adjoining panels.  This may mean that you will need to increase the center-to-center spacing of the lights to match that of the panel-to-panel gap.
    • Mounting or support - An important part of any matrix is how you will mount it - because a matrix tends to be a flat area (excluding pixel megatrees), you'll need to think hard about what system you'll use to mount the substrate on to which the pixels are mounted. If that surface catches the air, there could be problems with it blowing over or toppling the support structure.  Also consider that you'll need to store this mounting system in the off-season - so if the panels need to go into an attic, consider the opening going to the attic.
    • Substrate mounting - In most cases, you'll need to mount your pixels to a substrate - not only to support them but to maintain a clean and even spacing - there isn't anything worse than a matrix that has mis-aligned pixels.  How you mount those pixels can vary - it could be holes in coro like we do at HolidayCoro or it could be screwed or glued to wood slats or plywood - this all depends on your pixel type.
    • Pixel type - The type of pixel you select will often be a by-product of the distance and viewing angle of the people viewing your matrix.  These pixels could be in a strip form, node form or module form and each has it's pros and cons and there is no one pixel that is best suited for all matrix types.
    • Channels - Keep in mind that you'll often have many, many DMX channels on a matrix display and it makes sense to select pixel counts that fall within a set number of DMX universes - so don't design a pixel display that requires 180 pixels (18 wide by 10 high) if it could have been done in 163 pixels (18 wide by 9 high) which fits neatly into a single DMX universe and thus saves you a controller or controller output and also makes your sequencing easier to setup and manage.
    • Repairs - Factor in that pixels DO fail and that you'll need to fix them.  So consider how easy it will be to remove and replace pixels.
    • Cost / Budget - A matrix can grow in cost quite quickly when you factor in hundreds to thousands of pixels, so be sure to ask yourself the overall value of the matrix and how well it accomplishes its goal.  If this is just for announcing the radio station and song titles, a simple matrix will do - if you need to scroll logos or animations, you'll need a larger and more expensive matrix.
    • Big isn't always better - Since pixels have come down in price and complexity, we've seen a number of pixel matrix panels (and pixel megatrees) in displays that just completely over-shadow and "hog" the display.  We believe that a well balanced display should be the ideal and that one mega-element can leave your audience so fixated on one area that they fail to see other areas and animation. 
    • Software & Sequencing - Building a matrix panel is only one part of the process and the other major part is generating the sequencing for that panel.  Since it is nearly impossible to "hand" sequence matrix displays, you'll want to consider applications like LightShow Pro's matrix animator or Light-o-Rama's Superstar lights or other freeware applications that have been coming into the market.  You may even want to design your pixel display hardware, then start sequencing it before you buy or build it to evaluate how complex it will be to sequence the matrix. 

26 December 2013

Customer Question: How many lights can be hooked up to the TinyPix?

HolidayCoro sales/support often sees common, open-ended questions from our customers and here on our blog we post detailed responses publicly so that other people will be able to learn from the decision making process we use to answer these questions.

Today's question is:  "I see that the smart pixels 8mm come in a max of 100 per string, however a TinyPix can control up to 170 pix. So if I wanted to control 150 8mm smart pixels, can I do that with one TinyPix? If so, how would the 2 strings (100 & 50) be hooked up to the TinyPix, and what kind of power supply would be required? (I assume the 45w one would be too small for 150 8mm Smart Pxels)."

I can see that the customer understands that the TinyPix controller can handle 170 pixels (510 DMX channels (170 * 3) or almost a full DMX universe that is 512 DMX channels) as that is covered in our documentation on the product page.  I can also see that the customer is aware from the product page for the 8mm smart pixel nodes that the pixels come shipped in 100 count maximum per string.  So, we have several issues here, some of which we have information on and some we don't.

Design - There isn't any design information provided, so we don't know if these are being used in a concentrated matrix or string over a long distance, such as a pixel tree or a soffit on a house.  Why this matters is because if the pixel nodes are all close together, it can be fairly easy to inject power (more on that in a minute) as where if they are in a long single string over a distance, it can be harder/more complex to inject power.  Additionally, we don't know if this is for a single element or many elements and the distances of those elements.  We would be generally suspicious if the TinyPix is even the correct item for this design because we suspect that it would be one of several units where a centralized pixel controller would be a better match.

Signal - A TinyPix controller is a RS-485 based controller and thus needs a DMX source, such as our Actidongle.  A single Actidongle could output 512 channels, so it could handle the 150 pixels (450 DMX channels) without issue - IF - the customer only has one of these items with such a high channel count.  If the customer has several other 150 pixel elements, they would need more DMX dongles and at some point it is likely cheaper to invest into a centralized pixel controller with a E1.31 inface.  Again, since we don't know anything about the overall design the customer has in mind, we can't recommend a specific solution here or if the TinyPix is even the right item for this customer.

Power - An important part of any RGB design is power management - we've covered this in many articles and knowledge base articles.  So, given that we know we are going to have problems if we try hooking more than 150 pixels together end-to-end from a power loss standpoint, we recommend the customer review our blog post about how to manage power injection and power supply selection (because the customer had also asked if the 45w power supply was sufficient to power them.)

So, to recap - yes, the pixels can be connected end-to-end in an amount UP TO 170 but just because that can technically be done by soldering the wires together to make a single length, doesn't mean they will work without managing the power issues.  The issue at hand is that there will be just too much power drop over the pixel wiring and thus power injection would need to take place, likely at the start (through the controller power outputs) and again at the end of the string.  This is what we recommend with our 163 and 150 pixel scrolling RGB matrix signs since it is easy to put power in at both ends of the wire, thus resolving the power drop issues since everything is close together.  If the pixels were used on, say, the front of a house or to outline windows, you'd need to still carry the power to the end or middle of the string for power injection.

The second part of the customer's question if our 45 watt power supply will be able to power all 150 nodes.  So, first we need to look at the overall power consumption of the nodes, which is:  White (all three colors) 100 Nodes: 3.6 amps / ~44 Watts  We can see right away that at 44 Watts for 100, that a 45 Watt power supply isn't going to cut it since 44 (100 nodes) + 22 (50 nodes) would be 66 Watts total, plus add in another few Watts for line losses and a safety factor and we are up towards about 75-80 Watts to be safe.  This excludes looking at any other factors such as additional controllers, etc - hence, why it is good to know the overall design involved.  So, normally I would just recommend hooking up a 250 to 350 Watt power supply.  They are not that expensive and likely the customer also has other controllers that could also piggy-back off this same power supply.

So, in conclusion - the customer would best benefit by providing as much detail as possible about the overall scope of the project and where this specific element fits into that project.  We understand that often customer just want a simple answer to their question and do not yet understand the underlying complexities that comprise an important part of the decision making process.  In this case, it would be helpful if the customer were to review and then understand the power and DMX addressing issues under-lying the technology in the TinyPix (and all DMX controllers.)  While this process can be long and tedious - taking weeks or months for some customers, this knowledge is a fundamental requirement for customers selecting a completely DIY solution, as we talked about in our DIY vs Commercial solutions blog post.

19 December 2013

How many lights can be connected to a controller, what controller do I need for RGB lights, what wiring should I use for RGB lights and/or what power supply do I need for my RGB lights?

We often get requests from customers that ask how many lights they can connect to a controller, how many lights can be connected to a controller/power supply, what type of wire they need to hook up their lights and/or controllers or what power supply they should choose - and this blog post will work to answer those questions. This article assumes you are working with RGB lights and using a DMX based, constant voltage (all HolidayCoro controllers are constant voltage) controller, though the concepts will often apply to other controller types.  If the following information looks too complicated to learn or you'd rather just "have the answer", I'd recommend against working with a DIY lighting solution because a failure to fully understand the power requirements in some parts of the system can result in damage to the hardware all the way to house fires - and I've seen them both occur - so DO NOT "wing it" here.  Alternately, you can pay someone to "run the numbers" or there are vendors that sell plug-n-play systems and while they are not as flexible as a completely DIY system, there will be little to no need to understand power requirements - just plug-n-play.

The key to understanding how many lights can be connected to a given controller, it is important to see the lights and controller as only individual parts in a system that consists of:

Lights < Lighting Wiring < Controller < Power Wiring < Power Supply

Let's work through the chain and examine each part, starting with:

  • Lights
    • Purpose:  The lights are the final end-goal of any lighting system and they provide the light output for your display.
    • Selection:  Lights are selected on a wide variety of factors - more than can be fully described in this post but some of the factors are:
      • Physical:  You'll want to select the physical format, be that modules (square, rectangle, etc), nodes (8mm/12mm usually) or strip that best suits the mounting method and directional change (going around corners, curves, etc) requirements.
      • Voltage:  LED lights can come in a variety of voltages, usually 5V and 12V DC.  There are advantages and disadvantages of both of these common voltage ranges so refer to additional sources on proper voltage selection.  In general, you can go longer distances with higher voltage drops with higher voltage lights (12v) than low voltage drops (5v), though low voltage (5v) is much more power efficient and sometimes has brighter output.
      • Optics:  This can include output angle (60, 90, 180, 360 degrees, etc), color mixing (5050 on-die LED, Tri-Color 8mm, three 5mm separate LEDs, etc), light diffusion and many other factors.
      • Control type:  LED's can be controlled via constant current or constant voltage.  Constant current controllers are usually designed into dedicated systems like floods and it requires a specifically matched LED or LEDs to a specific controller as where constant voltage controller allows any number of LED lights as along as they are below the output requirements of the controller.  For pixel lights - the pixel is always supplied with constant voltage, even if in the chip it is constant current, so for pixels, consider them constant voltage devices.
  • Lighting Wiring
    • Purpose:  This wiring is either the wiring between each LED light in a string, such as in the case of RGB LED nodes or it maybe a circuit board in the case of RGB strip lights.  This wiring brings the power from the controller down to each light.
    • Selection:  There are no "standards" or "normal" wiring types here - each vendors wiring can be different.  One vendor may sell RGB nodes with 24 AWG wire (thin) compared to another vendor that uses 18 AWG (thicker) wire and they can look exactly the same.  I would not always trust the data provided by the vendor, more so if your supplier is outside the US as they often lie or copy other vendor specs even if they don't match the actual product.  In an ideal world, you would want the thickest gauge wire possible as it will be able to best transport the power with the least losses but the reality is that thicker wire is harder to work with (less flexible, harder to solder to circuit boards or lights) and is more expensive, so usually there is some "balance" between cost, weight and the distance needed for the lights to be run over.
    • Additional information:  Ideally, your vendor will list the maximum run on serially/continuously connected lights that can be supported before there is a "reasonable" drop in power.  So, for example, you might have one vendor that sells a 100 count string of 12v RGB nodes and they have a voltage drop from the start to the end of the string of 6v - or 50% of the power is used/lost between the start and the end.  Then you may have another vendor that has 12v RGB nodes that have a 3v drop over the 100 count string.  Again, this could be due to a number of factors - power consumption/design of each LED, gauge of the wire, quality of the circuit board, the type of solder used, the number of strands in the wire, the type of wire (100% copper, tin coated copper, tin only, etc.)  So, unless your vendor provides SPECIFIC information on how much power, over a given length at a given voltage the lights use - YOU MUST TEST AND MEASURE THEM YOURSELF!  Don't go by estimates or guesses - only trust the data.  When you've collected the power consumption amounts, you should then have a amperage (at a given voltage) or wattage for the number of lights or length of lights.  An example of this may be 37 watts per 5 meters of RGB strip.
    • Additional information:  You should always measure current draw with ALL colors on, so for RGB lights this means the light will be "white" in color.  Ideally you should leave the all lights on over a period of time (an hour or so) to get a true measurement as resistance goes up (along with higher power consumption) as the wires and lights heat up.
  • Controller
    • Purpose:  A controller is designed to rapidly turn off and on the power going to a light to create the impression of "dimming" - it does this usually through a process called Pulse Width Modulation.  
    • Selection:  Once you have selected your light type, then you've tested the power consumption, you can then determine which controller will be able to handle those lights.  Controllers are rated in amps or watts - which are the same thing when amps is combined with a given voltage.  So, if your vendor says that the controller can handle "6 amps per RGB channel" they mean that there are three individual DMX channels, each which can handle 2 amps - or a Three Channel DMX Controller.  The key here is - what is the voltage, so the voltage would be, say 12 volts, so if we use Ohms law, we come up with:  12v * 2amps = 24 watts, so this controller would handle 24 watts of power for each output or 72 watts per RGB channel (3 channels.)  So, if you've selected lights that you've TESTED to be 100 watts per "string" when they are lit up as white, than that single RGB output on the controller used in the prior example (72 watts) would not be sufficient to handle the load and you would either need to reduce the number of lights (less likely if the lights were planned correctly) or you would then need to divide up the load with either an additional controller or a multi-channel controller such as a 27 DMX channel / 9 RGB channel DMX controller.
    • Additional information:  Controller terminology comes in all different forms here are some of the common terms:
      • Channel:  Usually this refers to a single, two connection (wire, solder pad or screw terminal) output tied to a single DMX channel.  So a three channel controller would have three of these outputs and would also have three corresponding DMX channels.
      • RGB Channel:  An RGB channel is the same thing as a three channel controller - it means that with each of the three channels, red, green and blue can be controlled to make most any color.
      • DMX Channel:  This is a single output usually, that can be adjusted from a level of 0/zero/off all the way up to 255/on.
    • Additional information:  It doesn't make any difference if the controller is a pixel/smart controller or dumb controller - they both use power in the same way the only difference being that one can control each light individually vs all lights at the same time.
  • Power Wiring
    • Purpose:  Power wiring transports the power from the power supply to the controller.
    • Selection:  This selection is usually pretty easy and "by the numbers".  Those numbers are determined by the TOTAL power consumption of ALL the LEDs attached to the controller or controllers at the other end of the power cable - it has nothing to do with your controller because if you've properly allocated the maximum number of LEDs to your controller(s), than you just add them all up.  So, if you have two controllers, each with 50 watts of LEDs, you need a power cable able to handle 100 watts.  So, how do you select a cable that can handle 100 watts?  That depends on the distance to the controller.  So, these two factors - the amount of power you need to carry and the distance between the power supply and the controller(s) - we've covered this exact topic in our blog post about RGB wiring selection - check there for additional information and wiring selection charts.
  • Power Supply
    • Purpose:  To provide sufficient power at the correct voltage to the controller to power the lights.
    • Selection:  Power supply selection is the last item to select and is pretty simple based on a few factors, such as:
      • Total power consumption:  That same amount of power consumption that was determined in the power wiring section (the total power consumption of all the LEDs connected to the controller(s)) applies completely to the power supply.  If all your LEDs require 100 watts, you'll need AT LEAST a 100 watt power supply, though usually a 10 to 20% overhead is a good idea.
      • Form factor:  Power supplies can be purchased in many different forms - from waterproof, to water resistant to open frame.  Mainly this has to do with how you intend to use the power supply.  If the lights are inside, a simple shrouded power supply will be fine - no need for waterproof but if you are mounting it outside in a high humidity environment, you may be better off with a waterproof power supply.  Also consider how you'll attach or mount the power supply.  Also consider air flow as high wattage (250w +) power supplies often have fans and need a sufficient volume of air for cooling.
      • Voltage:  Of course the lights you selected at the start will be a given voltage and thus this applies to the power supply.  So, if you have 12v lights, you'll mostly likely need a 12v power supply.

We hope this helps you in the selection of the right wiring, power supply, controller capacity and lights for your project.  Here are some other related blog articles:

13 October 2013

Understanding the DMX Protocol and the RS-485 Relationship

I often get questions asking about DMX and how it works so I thought it might be useful  to recycle my presentation about DMX from the 2012 Academy that talks about the basics of the DMX protocol.

What can DMX do?
• DMX is simple – it is designed to control
devices, usually lights
• This may also mean just turning on and off a device
• Work with desperate devices and software applications

Where did “DMX” Come From?
• DMX was designed as a public standard to allow hardware and software vendors to all be able to
design inter-operation devices
• Designed in the early 90’s
• Developed by USITT – United States Institute for Theatre Technology
• Designed to be very reliable (but not guaranteed – no error checking)

What is DMX?
• DMX is a protocol
• DMX is a public standard
   - E1.11 (ANSI)
   - Just a set of rules
• DMX runs “over” other protocols or wiring systems

What DMX isn’t
• DMX isn’t a wiring standard
• DMX isn’t a physical “thing”
• DMX isn’t complicated
• DMX isn’t the perfect protocol

RS485 and DMX
• It is important to understand that RS485 ISN’T DMX and vice-versa
• RS485 is the most common method of DMX transmission

Here is a table that shows how DMX (E1.11) compares to other layered systems:

• RS485 is the “road” on which DMX runs
• Very robust – designed for industrial environments back in the 1970’s
• Differential signaling system (positive and negative voltages)

Here is an example of how a differential signalling system works:

• Able to handle speeds up to 35 Mbit/s depending on cabling
• Cable lengths up to several thousand feet
• Two wires + ground (optional)
• Allows for a variety of wiring topologies 
• RS485 is the basis for DMX (E1.11) , LOR, Pixelnet and Renard protocols 

RS485 Termination – Yes or no?
• PRO: Termination “dampens” the reflections of the signal in the cable
• CON: Termination “sucks up” power on the line, lowering the voltage and thus the distance
• The RS485 (DMX) specs call for termination (100-120 ohms) with standard DMX cable
LOR Controllers don’t use termination 
• No one best answer – sometimes it is  necessary…sometimes not 
• A scope is the best tool for looking at the quality of the signal
• For video showing the effects of termination: 

Splitting RS485
• Some controllers passively split the connection (LOR/LE Express) and some actively split and then repeat the signal (LE Express)
• Splitting DMX can be as simple as using 3-way splitters
• Keep “stubs” as short as possible

Connectors and Cable (E1.11)
• The E1.11 DMX standard says to use 5 PIN “XLR” plugs (there is also a section about CAT5)
• Many lighting industry devices use 3 PIN “microphone” cable with XLR plugs instead as it is more common
• The holiday lighting world uses CAT5 cable and connections almost exclusively – as they are cheap

RS485 Wiring
• Chart showing wiring interconnections:  http://www.holidaycoro.com/kb_results.asp?ID=46
• Ground wire often not connected in holiday lighting controllers

Controller Count per line
• Technical limit to the number of devices on a single DMX line is 32 but many more are 
possible depending on the line load per controller (actually the RS-485 chip).  I've personally used 90, 3 channel DMX controllers on a single RS-485 line.
• Controller counts can be increased with the use of repeaters (not common)
DMX over Ethernet (E1.31)
• No RS485 - DMX is instead sent over standard Ethernet/Wireless using TCP/IP
• Allows many universes over a single network connection
• Used when distances are far or channel counts are high
• EtherCongateway (J1SYS) / SanDevices controllers or other high-channel count pixel controllers

DMX Channels and universes
• There are 512 channels (9 bits) in a DMX universe
• One transmitter (RS-485) per universe
• One transmitter (E1.31) for many universes
• Universes are effectively unlimited
• Universes are not “connected” to another universe

DMX Protocol Internals
• DMX runs at 250Khz or 4 micro seconds widths/”slices” of time – 1 Microsecond (µs) = .001 milliseconds (ms) / 1000 ms = 1 second
• MTBP – Mark Time Between Packets (idle)
• Break – Starts with 88 µs low/ 22 pulses (get ready…I’m about to send data)
• MAB – Mark After Break ~12 µs high / 2 pulses
• Channel Data - 44 µs / 11 pulses for each channel (shown in red below)
  – Start bit– 1 bit low
  – Data bits – 8 bits (0-255 that define the level of light intensity)
  – End bits – 2 bits high
• First channel zero, has the start code of binary 00000000 (zero) 
• MTBF - Mark Time Between Frames 0-1 seconds high (the next channel is coming up)
• All 512 channels are sent one after another until the next MTBP and the process restarts

DMX Packet Timing
• Timing References
  – 1 Microsecond (µs) = .001 milliseconds (ms)
  – 1 Second = 1000ms
• [(88)+(12)+(44)+(channels*44)+(channels*MTBF)+(MTBP)] µs
• 88+12+44+22528+0+50 = 22,722 µs
• 1,000,000µs (1 second) / 22,722µs = 44.01 Hz or 44(times per 
• This means that as long as your sequences contain timing no smaller than 22ms or .022 seconds, the timing of the display will be as expected

Output Adapters / Dongles
• DMX must be generated by a device
• Devices can be “Smart” or “Dumb”
  – Smart – Command is sent to device from the sequencing software (say…Channel 1 at 128 bits) once and the devices keeps repeating it 44 times/sec. This way the PC doesn't need to keep repeating it. 
  – Dumb – Commands from the sequencing software have to be re-sent over and over 44 times/sec. This puts a larger load on the PC
• Adapters/Dongles
– Smart – HolidayCoro ActiDongle, Enttec Pro, DIYLA Dongle
– Dumb – Enttec Open, generic RS-485 Adapters

Levels of Fading
• Each channel in a universe carries 8 bits of data, allowing up to 256 (FF hex) levels of fading per channel.
• 0 = Off
• 128 = Half on
• 255 = Full on
• Fading “quality” can be affected by lighting curves, linear lighting output

See the following videos for example of what this looks like:

DMX Effect Generation
• DMX Devices don’t generate any local effects, unlike the LOR protocol which generates it’s effects in the controller hardware
• Effects are generated in software
• This means that effects can be changed easily as they are created in the sequencing software

LOR Users – How get DMX
• LOR S2 Users – Upgrade to LOR S3 Advanced
• Native in LOR S3 using Enttec Open/Pro (supported by LOR) / Lynx Dongle / HolidayCoro ActiDongle
• Native in LOR S3 using Lynx Dongle
• iDMX-1000 – converts LOR protocol to DMX  (not recommended)
• Play sequences in xLights – better output support and less moving parts

• LOR Controllers can listen to LOR and DMX allowing you to run all your controllers as DMX (DIY and LOR)
• There is “to spec” and there is “it works” – this is Christmas lights after all

• DMX Standards:
– Recommended Practice for DMX512 from USITT – book, purchase only
– BSR E1.11 Standard from USITT, book, purchase only
• RS-485

08 October 2013

How To Question: Pixel Arches

Today's question comes from Phill who asks:

After reading, and watching several videos on your site, I would like to test an RGB Pixel setup (100 lights per string, using your tinypix controllers). I am using LOR S3 Advanced software, and would like you to verify what I will need (to make sure I don't miss anything).

Currently, I am just using the inexpensive Light-o-Rama USB485 dongle, at 500K (network speed), and it works great - will that work, or do I need to use one of your dongles, and if so which one - Ultimately, I will be using this for 12 arches (50 pixels each).

I know I need a 100 light pixel string, 1-tinypix, programming cable, and power supply - for the testing of the single string, I will just use one I have on hand). other then the possible dongle, is there anything else I will need???
So let's break down this issue - Phill would like to make pixel arches and he has indicated that he needs 12 of them at 50 pixels each.  My first question would be - what type of RGB pixel is being used here?  My guess is pixel strip given that the number is 50 pixels and pixel strip commonly comes in 16' lengths that contain 50 pixels (150 DMX channels), so we'll go with that given that pixel strip is a reasonable choice for pixel arches.
The next question I'd have is - what type of interface is going to be used here to get the sequencing data to the pixel controller?  50 pixels * 3 DMX channels (Red, Green, Blue) * 12  = 1,800 DMX channels - so that's a fair number of pixels and is comprised of 3 DMX universes (actually 4 because you would likely put 3 arches of 150 pixels each, within a single DMX universe of 512 channels.)  So, I think an RS-485 interface is out of the question here - the customer is going to need to go E1.31 for output of that much data.
So, to answer Phills question about LOR - yes, you'd need at a minimum LOR S3 advanced to get enough output and E1.31 support.  Phill would run the LOR network separately of the DMX network, so Phill's LOR settings really don't matter here since they don't impact the DMX E1.31 network.
Phill mentions needing a "100 light pixel string" which isn't correct based on my assessment that he has chosen RGB pixel strip, so maybe he is referring to 8mm pixel nodes?  If that is the case, usually 8mm pixel nodes would be a bad choice for this design - they don't mount well, you have to get them pointed in the right direction and they have less light output than the 5050 RGB chips in RGB strip - so we are going to just forget the 100 light pixel string reference and again assume he needs RGB pixel strip.
Phill also mentions needing a TinyPix -  I can't say if that is the case because I know nothing about the distances involved.  A centralized controller is great, something like the SanDevices E68x or the J1Sys controllers but they do have limits on distances you can place elements from the controller - yea, you can use null/ghost pixels to span longer distances but I'm not sure if we are talking 2 acres or a 5,000 sq/ft yard.  In the 2 acre, now a distributed pixel controller like the TinyPix really makes sense, if you have them all very close to each other, a centralized controller makes sense.  Now please note that the TinyPix is RS-485 based and thus would require "dongles" for output of each DMX universe as where the centralized controllers would require an Ethernet feed from the show computer.
So, to completely answer a question such as those posed by Phill, we need to know other relevant data such as:
  • The physical design and layout of the display elements (arches)
  • Any additional pixels/DMX channels used in the display
  • The method the user will choose to sequence the display (software)
  • The budget range for this project
  • The skill level of the customer (plug-n-play or DIY)


28 September 2013

Locating and Repairing Bad Pixels

If you have pixels - be they nodes, modules or strip - at some point you are going to have a failure.  That failure could be when you purchase them or over a period of time due to physical damage or other causes.  So, you'll need to have the ability to locate and then replace the bad pixel.  This video shows how to perform this process on nodes (8mm / 12mm) but it also is the exact same process if you have any other type of pixel. 

As mentioned in the video, if you do pixels, you'll need to solder and it's not nearly as complex as you might expect.  Check YouTube for videos on how to solder.

27 May 2013

A Demonstration of the Effects of Power Draw on Long Lengths of RGB Lights

Todays blog post is about the effects that power draw has on RGB lights.  We've taked about it before in our blog post about how wiring affects power distribution and in our demonstration example house where we lined it with pixels and handled the issue of power consumption.

This video is pretty simple - it shows 160 pixels (480 DMX channels) connected to a single power supply and our HolidayCoro pixel controller.  It is intended to show the effects that the gauge of the power wire and the power consumption of the pixels themselves have on the actual light output.

(open in YouTube with High Def for better viewing)

Post any questions below.


08 May 2013

I want to control an high power LED - How do I do that?

There are a number of different high output LEDs on the market - they commonly run 1 watt, 10 watts, 30 watts and more.  We will often get the question - can I use your controller to run this LED?  Well, yes and no. 

Think of an LED as an engine in a car.  A modern car has a throttle and a rev limiter (usually controlled by the cars computer.)  So, if you press the gas pedal all the way down (more so for a manual shift car as opposed to an automatic), the car will speed up (if in gear) up to the point where the rev limiter kicks in and it prevents you from running the speed of the engine faster than the engine can handle (and thus destructing itself.)  So, in this example, think of the "bare" LED as an engine - it will take all the current (power) you can give it as long as the power supply can supply it - and it will do so right up until it burns out, which could be seconds, minutes or longer (thermal and voltage issues determine this rate.)  So, just like with a car and its gas pedal and rev limiter, your LED needs the equivalent of the rev limiter and that is called a Constant Current Driver.

In a car we have gasoline that provides the power that keeps the engine going but in an LED it is electricity that provides the power for the LED to operate.  In the same way that a throttle (or some function of the cars rev limiter system) modulates the amount of gasoline that reaches the engine, a Constant Current Driver circuit limits the amount of current that can reach the LED. 

There are two general methods you can use to modulate the current in an LED - a Constant Current Driver circuit or just simple current dropping resistors.  A CC driver circuit is ideal but requires more complex parts, usually an IC plus some other minor components.  A current dropping resistor circuit is either one or several, simple resistors that limit the amount of current that can reach the LED, thus "limiting" it's current.  Each method has it's pros and cons.  The CC driver is ideal because no matter the input voltage (up to a point), the CC driver will still maintain the exact same amount of light output as where a resistor dropping circuit will fluctuate the current level based on the input voltage.  This means that you can have LEDs (using dropping resistors) at the start of a long string be brighter than those at the end of the string as opposed to a CC driver which would produce the same light output along the entire string (generally speaking.)  So, you think - heck, why don't all LEDs have CC drivers?  It's an issue of cost - if you have individual nodes or modules, each one will require a method to control the current and it is generally much cheaper to use resistors than a more complex CC driver.

So, what if you want to make your own constant current supply for your LED?  We'll first you'll need to know the specs that are included with your LED, this will include the voltage of the power supply, the forward voltage of the LED and the forward current of the LED.  If you are using RGB, each color will often have different values.  Next you need to determine if you want to build a resistor dropping solution (cheaper, easier but less tolerant to voltage changes) or a true constant current solution (more expensive, more complex but safer and more consistent light output).

For how to build a dropping resistor solution, see this website - it provides the exact wiring for the resistors and LEDs and the size and values of the resistors.  For how to build a constant current driver, see this website.  While this site refers to an arduino for control over the circuit, you can use the standard, dumb RGB DMX controllers HolidayCoro sells for driving the CC circuit.

This is just but a small part of the overall issues involved with this subject but hopefully it is helpful in explaining some of the basic concepts.

For additional in-depth information on how LEDs are driven, you can see this website or many other websites on the Internet.

30 April 2013

The Nearly Famous RGB Video Series - Everything You Wanted To Know About Pixels But Couldn't Find The Answer

When I started researching RGB and pixel solutions in early 2010, there was just about no information on the internet as to what all the teminolgy, protocols, wiring, controllers and other items were.  After extensive research and work with others, I decided to document all the information I knew at the time in the form of a video series.  The focus behind the videos was to simply show each type of lighting, controller, wiring, etc in a non-vendor specific manner so that someone just getting started out could get up to speed on the terminolgy and functions.  This information, while produced in late 2010, early 2011 is older now, every bit of it is still completely relevant.  Since this information is squirrled away on our website, I though I would repost it here for those new to RGB and pixels.

The videos below cover the general topics of RGB as they relate to Holiday Lighting.

  • Video #1
    • What is RGB?
    • What are the different type of RGB lighting devices?
    • What is Basic RGB and RGB Pixels?
    • How to Pixels get their addresses?
    • How do you assign channels to pixels?
    • What are controller macros?

  • Video #2
    • How do I fix dead pixels?
    • What is the difference between three and four wire pixels?  Does it matter?
    • How do I know which end of my pixels to hook to the controller?  Does it matter?
    • How do I power my pixels?
    • Why are there different voltages for pixels?
    • What is the difference between centralized and de-centralized power distribution of pixels?
    • How many pixels can be on a single controller output?
    • What is color depth in pixels?  Why does it matter?

  • Video #3
    • What are the different type of pixel chips?
    • What quality issues should I be aware of when purchasing pixels?
    • What are the drawbacks of RGB over just regular Christmas lights?
    • What advantage do Basic RGB and RGB Pixels give me?

  • Video #4
    • What are the different types of Basic RGB controllers?
    • Why would I want to use basic RGB controllers and LEDs instead of pixel based controllers and LEDs?
    • What are the different types of RGB Pixel controllers?

24 April 2013

Outlining Your House in RGB Lights - Detailed Instructions

Updated 25-Aug-2015 with Brilliant Bubs and Updated Spredsheet

In our prior blog article – Outlining Your House in RGB Lights – A Primer we covered the high level decisions that needed to be made when designing system for RGB lights on the fascia of a house.  This article, unlike the first, provides in-depth information on how to layout and spec such a design.  Not included in this article are the specific step-by-step instructions on how to wire controllers, wire power supplies, how to solder or any other physical setup – but don’t worry – that is actually the easy part, it is the design that most people find the more complicated part.  I should also mention, just as our blog article No Free Rides – Cheap Isn’t Free When It Comes to RGB – there isn't an “off the shelf” solution for doing this – each house, each display, each budget and each level of skill is different and the only person that knows all these requirements is yourself.  So, expect to spend some time doing research for a complete solution.

One last thing - if you have not already done so, be sure to start with our RGB Projects Primer post.  This post covers all the major steps you need to consider when designing a pixel based project.
Ok, so let’s get started.  We have selected the house of Nathanial R. to build this real-world sample project from.  This house (shown below) has many areas that need to be covered – 19 in all, so this house will serve as a good example of how a house with many complex roof lines can be handled.


Design – Always the first step

Often people try to determine which hardware will fit their house without first starting with a design.  The absolute best method is to always start with a design prior to purchasing anything.  Design can comprise many aspects but in essence it is – What do you what your display to look like?
Normally you would look at the entire house/display and determine all the elements that you wanted to add – mini-trees, megatrees, bush lights, candy canes, cutouts, garland, icicles, borders, etc. and then create separate “projects” to focus on each one.  In this case we are focusing on a sub-element of Nathanial’s display – to outline the fascia of his house with RGB pixel lights.  He has already determined that he likes this look but just isn't sure what is required and the issues involved in the project.
So, start this project by going outside and taking a photo of your house from the approximate location(s) that your viewing audience will view your display.  These photos will serve to allow you to sketch out your design and to also layout measurements, cable routing locations, controller locations and other relevant information.


Smart or Dumb?

This is the first major intersection on your project – you need to determine if you want to go the dumb RGB or Smart RGB route.  Here are some of the pros and cons of each for this project:

RGB Smart/Intelligent/Pixel
RGB Dumb/Basic
Lighting Costs
Smart RGB modules and strip are about 10-30% more expensive than dumb of the same physical items (modules, nodes, strip).
Lights are about 10-30% cheaper than Smart.
Lighting Functionality
Smart RGB lights can be controlled either by individual lights or in small sections (usually less than 3” each).
Dumb RGB lights cannot be controlled individually – all lights attached to a controller will be the same color and intensity.
Controller Costs
Smart RGB controllers are about 50% to 100% more but generally you need fewer since pixels can be used with power injection.
Controllers are less expensive but you are likely to need more of them along with more power wiring.  Long runs are extremely complicated to perform with dumb RGB.
Controller Functionality
Smart pixel controllers are able to control each light or small section of lights individually.
Dumb controllers can only control a string of lights, not individual lights within the string.

Today, in 2015, it is hard to make a good case from going with dumb RGB for a house outline in all but  few cases.  Pixel solutions are easier setup than dumb and the cost differences are minimal when all other factors are included.  If you are going dumb RGB outline, you should know why it was selected over smart.

A few caveats on this – some people would design this using pixels and using either functions in their software or controller, would limit the control to sections or controller outputs.  Some pixel controllers have an option to control an entire length of pixels with just three DMX channels instead of each pixel with three individual DMX channels.  This allows simplicity in setup and sequencing at the trade-off control but still allows moving to a full pixel display later on down the road when you are ready to do so.
For simplicity and brevity, we will be focusing only on pixels in this case since this is the direction that Nathanial has decided to go - though you will find dumb or basic RGB have many similar design requirements (power, signal) but just slightly different hardware (controllers and lights) than pixels.


House Measurements

An absolute requirement for this project is to determine where you want your RGB lights to be located.  To do this you will first need to determine where you will be installing them and how you will be installing them.  We won’t delve into specific mounting methods as there are just too many options depending on your house constructions and overall look you are going for – such as under soffit “wall washing” instead of fascia mounted or directly viewable RGB lights.  (See our budget PVC pipe mounting method here and our high-end aluminium mounting strip here.)
So, get out your ladder, tape measure, thinking cap and determine the exact length of each section where you wish to place the RGB lights and record it on the photo of your house.  When you are done you should end up with a photo that looks something like this: 

You can see that he has measured each and every section of the fascia that he intends to mount the RGB lights to.
Why does it matter that you are accurate in the measurements you take?  The reason is that, depending on the RGB lights you intend to use, even just several inches of RGB pixel lights could result in 3 to 6 DMX channels and if you miss a few inches here, a few feet there, your final design could be off several dozen or hundreds of channels depending on the size of your display.  This is not to even mention the issues in properly calculating the power consumption.


Selecting RGB LED Types

The next step is to determine the actual type of RGB Pixel LEDs you will be using.  Which pixel type you select depends on a number of factors, such as the density of lights and control you want, the amount of cost you want to expend, the type of “look” you are going for and a number of other minor factors.  Let’s go through some of the areas you should be looking at when you select the type of RGB pixels you intend to use:
·         The “look” you want to achieve – There are a variety of different types of pixels on the market – nodes (with and without diffusers), strip and modules.  You need to determine the type of look you want – is it a more retro look like with C7/C9 diffused RGB nodes or do you like the close spacing in strip that offers a more “neon” appearance?
·         Costs – Each different type of RGB light has different costs.  Some of this cost can be a result of a better quality pixel, level of control it offers or density the RGB lights in the pixel.  Typically, strip lighting is always going to be the lowest cost method of getting RGB lighting onto a house outline.
·         Mounting – Each pixel type has a different method of mounting.  Some may be able to use existing mounts such as those based on C7/C9 devices (rare) or they may require a mounting substrate (PVC pipe, 1"x2", etc).  Think about how you will be mounting the type of RGB pixel you select and what effects it will have on the mounting method and the cost of that method.  Also keep in mind how complex it will be to mount and dis-mount the pixels – saving 50 cents per pixel won’t seem like a great deal if it takes you two times as long to mount them.


The Number Crunching

A this point you have now selected the types of lights you want to use and you have collected the lengths of each section on your house that the lights will cover.  The next step is to enter this data into our spreadsheet.  This spreadsheet (requires MS Excel 2007 or later) only requires you to enter each of the lengths (sections) within your project and select the type of light (strip, module, node) you wish to use and it will then output costs, number of RGB and DMX channels and power requirements.  This gets you part of the way toward your final design and it also allows you to play around with different lighting to determine channel counts and costs but it can’t completely design your display because there are just too many factors to take into account.  There are many small but important decisions that need to be made based on the specifics of your house and design.  Here are some of the issues:
·         Location (and type) of controller(s) – There are three basic options for pixel controllers – a centralized controller solution, a de-centralized controller solution and a mixed centralized/de-centralized controller solution.
o   Centralized – These controllers, such as the AlphaPix 4 and AlphaPix 16, are units that take an input of DMX data (over Ethernet using the E1.31 protocol) and output over 4 or 16 outputs (separate strings or DMX universes).  This means that you can hookup a single string of RGB pixels, ranging from 320 (AlphaPix 16) to 680 (AlphaPix 4) pixels per controller output.  There are some issues here though – there is usually a limit to the length of distance between the controller output and the start of your string of lights and these limits vary but are often (with most pixels HolidayCoro sells) around 15 to 20 ft.
o   De-Centralized – These controllers, such as the EasyPix allow you to take an input of DMX data (from a DMX dongle, such as the ActiDongle or from the RS485 output of our AlphaPix controllers (3 on the AlphaPix 16 or 1 on the AlphaPix 4) and output the data to a pixel string, usually up to 170 pixels per controller.
o   Mixed Centralized & De-Centralized – There maybe cases, most often with large houses or wide spaces, where it makes sense to use a mix of these two controller types.
o   Power Management – Just as important as getting a data signal to pixels is getting the proper amount of power to the pixels and there are a myriad of issues involved, such as:
o   Cable/wire gauge – This is a complex issue but it really boils down to ensuring that for the amount of power you will be using, that you have sufficient method to get it to where it is needed and this means using a wire gauge that meets that need.  We've talked about this in our “Technical Guide to RGB Wire Selectionarticle, so we suggest starting there.  Be aware that the wire gauge involved isn't just that leader cable from the power supply to the pixel but the actual gauge of the wire inside the pixels themselves.
o   Power consumption of each pixel (or group of lights that make-up a pixel) – The spreadsheet will help with this calculation but also be aware that there is a limit to the number of pixels that can be run in a continuous length due to power consumption by the pixels themselves.  Some pixels may only be able to be run continuously in lengths of 40, 50 (common in 5v pixel nodes), 100 or they may be able to take a single injection of power at the start and run for a full universe of 170 pixels (510 DMX channels).  For most of HolidayCoro's pixels, you'll find a information on power consumption and length limits before power injection is required.

This is why you see 12v pixels vs. 5v pixels.  A 5v pixel is closer to the actual voltage of the LED and IC chip using the power and thus is more efficient as where 12v has to be “dropped” down by use of a voltage regulator circuit (not as common) or dropping resistors which waste the power.  The trade off is that you generally can run 12v strings of pixels, given the same gauge wire, longer distances than you can 5v pixels without the need to re-inject power as often.  This is an entirely separate and complex discussion.  In general, you'll find it "easier" to work with 12v RGB lighting which is more forgiving than 5v lighting which requires more accurate planning and power management.


The Real World

Now that we've covered many of the basics, we are ready to turn our attention back to Nathanial’s house and start working through the design.  First, we input the data into the spreadsheet (version 2.1 / 25-Aug-2015) and select RGB pixel strip as the type of lighting we want to use (RGB Pixel Strip in this case):

This provides us with some important starting points:
·         The total number of DMX channels is 1,308 and since each DMX universe is 512 (actually 510 for pixels or 3 channels * 170 pixels), we end up with needing 3 universes.
·         We will need a total of 436 RGB sections and/or RGB channels
·         We will need about 324 watts of power
So, now let’s go back to the photo of the house and the location of each section of RGB strip he intends to use:

The first issue we need to address is that with some controllers (does not apply to HolidayCoro AlphaPix controllers) no one continuous length of strip can be more than 170 RGB pixels/channels (510 DMX channels - Red, Green, Blue channels * 170 pixels) in a typical controller.  As a result, we need to look at logical sections that might be a continuous length and determine if they are under 170 RGB channels or less.  If we look at the front section of the garage facing the street, we have a total of 26 linear feet of strip we need to place.  We can see that the spreadsheet has calculated that this is a total of 80 RGB channels – OK, good there, what about if we include the side of the garage over the garage doors at 34 feet.  We get 182 RGB channels – nope, can’t do that, its 12 RGB channels over the output of any single output (170) so our options are to either adjust the lengths and remove a section, or break it down into two sections.  We are going to go with two sections for the garage section – with 80 RGB channels for the front of the garage facing the street and 102 RGB channels for the section of the garage over the garage doors.
We’ll do the same for the top of the house with the sections that are 8.5’ + 8.5’ + 1’ + 9’ + 15’ + 11’ for a total of 53’ linear feet and a total of 160 RGB channels.  Then for the bottom section of the front of the house at 6.5’ + 6.5’ + 9’ + 9’ for a total of 31’ or 94 RGB channels.  So, to summarize, we have the following segments:
·         Garage Front:  80 RGB Channels & 240 DMX channels
·         Garage Entry:  102 RGB Channels & 306 DMX Channels
·         Front House Top:  160 RGB Channels & 480 DMX Channels
·         Front House Bottom:  94 RGB Channels & 282 DMX Channels
You can see these numbers match perfectly to the spreadsheet calculations of 436 RGB channels and 1,308 DMX channels.  Of course this assumes that your controller can handle a total of 170 RGB channels per “output” – adjust as necessary to meet the specific requirements of your pixel controller.

Power Distribution

This is where things can get a little tricky – while we will be selecting a controller that can output a total of 170 RGB channels, that doesn't mean that if we apply power to the start of the strip (in this case), that a sufficient amount of power will make it to the very end.  As power runs down the strip, most of the power is lost to the LEDs using the power and the remainder is lost to the resistance in the strip itself or the wire between modules.  So, we go back to the spreadsheet again and we look at the power consumption for a given grouping of sections.  We get:
·         Garage Front:  60 Watts
·         Garage Entry:  76 Watts
·         Front House Top:  119 Watts
·         Front House Bottom:  70 Watts
Here is where it gets a little grey – you can check with your lighting vendor and they may list voltage drop over a given length of RGB pixel – say, input of 12v, 11.5v at 50 pixels, 8.5v at 100 pixels and 6v at 150 pixels but that isn’t common, so more than likely you’ll need to measure this yourself.  How you do this is:
·         Hookup a section of RGB pixels, say 50 or 100 to your pixel controller
·         Using your sequencing application, the built in test function of your controller or a test tool like xLights, output a solid white to all the lights on the section you are testing.  I’d recommend leaving it on for 15 to 30 minutes to let it warm up, which will result in a slightly higher power drop.
·         Using a multi-meter/VOM, measure the voltage coming directly out of the controller to the lights – record this voltage
·         Again, using the mutli-meter/VOM, measure the voltage coming out the last pixel on the string – record this voltage
You should notice a drop in voltage at the end of the pixel section.  How much of a drop is bad?  Well that depends.  Usually less than 10-20% is ok, over that amount you could run into problems either with a dimming of the lights at the end of the string or in the worst case, if the voltage drops low enough, below that required by the IC chip to operate, your pixels will have “random” failures as the voltage fluctuate from high to below what is required for the IC to operate.  This is why running 12v pixels can sometimes be less fraught with issues than 5v pixels.  For example, look at these hypothetical voltage drop examples:
·         Input:  12v / Output:  7v | 5v total drop – A total drop of 41%
·         Input:  5v / Output: 3v | 2v total drop – A total drop of 40%
So, even though the 12v pixels dropped a higher voltage, it was still the same percentage of drop when compared to the 5V dropping to 3v.  Now this is where it gets a bit complicated.  Say that the power has dropped to 3v at the end of that hypothetical string of 5v pixels – normally a pixel chip requires around 5v of power to operate but some pixels actually can take lower levels of power and still maintain operation and a the same level of light output.  For example, WS2801 pixels can run on voltages from 3.3 to 5.5v DC (12v strings that use 2801 drop the power down by using resistors) and maintain a constant current to the LED (thus ensuring they are all the same brightness) but TM1804’s are constant voltage and the LEDs will dim over long runs without power injection.  There are also side issues such as power losses on 12v pixels but that maybe a mute issue for those in snowy areas that find value in a “heated” pixel.
We would always recommend testing your build before and after construction because nothing will be more frustrating than putting all this up only to learn that you’ll need to re-wire it because of power issues.
What do you do if the power drop is too great?  We’ll you’ll need to split the power about half-way down the line, and then using a higher gauge wire (14 AWG and up is always a good start) from the power supply up at the start of the string, carry the power down to the split – the data will pass right through (it is regenerated at each pixel).  This diagram shows and example of the power injection:


Controller Placement

We’ve already touched upon the three different types of controllers – centralized, de-centralized and a combination approach.  Now it comes down to the actual placement of those controllers.  There are three additional major items to consider here, other than the controllers themselves – where the DMX is coming from (and how much it costs), the overall cost of the controller(s) and distances from controller to the strings they are driving.
DMX Signal Source – There are two major methods of DMX signal generation:
·         Serial based DMX output dongles – these devices (such as the ActiDongle) connect to a PC via a USB port and appear usually a as “COM” port or similar interface.  Each dongle outputs 512 DMX channels to an RS-485 line (see our blog article on RS485.)  These are used with controllers that take a DMX over RS485 connection.
·         Ethernet based DMX output – some controllers (AlphaPix 4 and the AlphaPix 16) take a direct Ethernet connection into the controller and use the E1.31 protocol which is basically DMX running over TCP/IP (running over Ethernet.)  While somewhat more complicated to setup, E1.31 offers huge numbers of DMX universes in a single data cable.  This means that you could have as many as 16,320 DMX channels on a single CAT5 Ethernet cable to a single controller.
Controller Costs – In almost all cases, it is less expensive to hook up a E1.31 based controller to drive pixels (as low at $129 USD) vs an RS485 based dongle ($50) and a pixel controller ($40) - the difference being that the E1.31 controller could handle 2,720 pixels and the RS485 based controller could only handle 170 pixels. 
Here are some of the thought processes I go through when looking at this design:
·         If the controller supports forward or reverse addressing, I'm not limited to putting the controller on the left side with the strip going to the right (left right addressing is easier and more common.)  So when I look at the house I see at the front corner of the garage two different start/ends occur which could allow me to place one dual output controller there along with a power supply.  I also see the same thing above the front door where the top of the bottom sections of the house come to two points.  All HolidayCoro pixel controllers support forward and reverse addressing.
·         I know I’ll need four outputs since we have already determined that we need four separate sections of strip.  I also can tell that I need to keep the strip under about 30ft to avoid power problems so for the section on the top of the house (30 LED/10 ICs or Pixels per Meter) I’ll need to do power injection but for the other sections I should be ok for power injected at one end of the strip.  Again, you'll need to do your own testing here to determine maximum length.
·         I could place a single, centralized controller on the wall above the front door but I need to consider that it will have long lengths from the controller to the start of the strings (much more so for the string on the front of the garage) and while I could use ghost pixels to repeat the distance, I still would be using a large controller in an awkward spot and I would have a controller with a lot of extra outputs that I won’t use (in this design.)
·         I could use single or dual output controllers and place them at the corner of the garage and above the front door and that would remove my issues with distances but would still mean that I would have controllers in an awkward spot directly in the front of the house.

So, what was the final design decision?  A centralized controller.  This was selected for the following reasons:
·         Ghost/Phantom/Null pixels can be used to repeat the signal from the centralized location where the controller is located to the start of the string.  That resolves the issue with distance (within reason.)
·         The additional outputs of the controller (16 outputs total) can be used for other elements within the display.
·         In this design the power requirements (324 watts) match up well with a single 350 watt power supply.  This isn't to say that more power could be required - test, test, test!
·         This allows a E.131 connection without additional dongles – so one cable for all the channels required.
Here is a photo showing the final layout:

·         The green lines are power (12v DC in this case) using a minimum of 16 AWG wire
·         The purple lines are data (SPI) signals from the controller to the strip
·         The green circles are where power injection on the strip occurs
·         The blue square is the 350 watt power supplies (or supply)
·         The red square is 8 to 16 output pixel controller
·         The orange lines are the pixel strip
·         Black dots are estimates for locations of null/ghost pixels
Our overall hardware costs for this project are:
·         $175 for AlphaPix pixel controller
·         $40 for 12v, 350w power supply
·         $70 for misc wire (extensions and bare wire)
·         $60 for mounting substrate and clips (estimate)
·         $70 misc additional costs (screws, connectors, etc)
·         $770 Total
So there you have it – while this is a very lengthy article for a blog posting, it doesn't encompass EVERY feature, function or possibility – this article should help you work out the major issues in completing a project of similar nature.  You will also notice that we have not even covered the software side of this project – setup of E1.31, configuration of the channels within a sequencing application or even issues involved with sequencing 1,308 channels which is a project unto itself.  We hope to tackle this issue in future blog articles, so stay tuned!
Please note that due to the number of requests we receive, HolidayCoro is unable to provide free design services due to the amount of time it requires to evaluate each individual solution.  We do however, offer consulting services if you should need them.
Thank you,

Here is a follow up video that shows a design process using RGB nodes: