HTINews Feature Article
|Which One Should I Use - Part IV
Complex Residential Coupling
with Considerations for Dim/Bright
by Phil Kingery
First, to everyone who attended one of my classes at the Habitech Convention in Dallas, June 23-28, it was a pleasure meeting you. Thanks to all of you, I was given the "top instructor" award at the convention. Knowing the caliber of many of the other speakers, it was indeed a great honor. On top of that, it was also a great convention with lots of new products. (There was also a lot of old products with a "new coat of paint".) I always look forward to these kinds of conventions since it is like a reunion for many of use who only see each other every year or so. I am also looking forward to the upcoming "International Security Conference" (Jacob Javits Center, New York City, August 25-27). This will be my first opportunity to speak at the ISC. It has been described to me as a "feeding frenzy" for security people. Ill let you know if I survive.
- What if the job is so large that even an ACT coupler/repeater is not enough?
- What if I want to take some signal from one distribution system and send it to another distributions system?
- When do you use a true amplifier?
(I also threw in a couple of questions just to see if you were paying attention, like "What was Spocks first name?"...and "Why dont the words comb and tomb rhyme?".) I was surprised that I received so few emails asking about complex coupling and true amplifiers. I was not surprised that I did get a few emails on Spocks first name (but that is another story...). As far as why "comb" and "tomb" dont rhyme, sorry, I dont know.
Before we begin, I must confess that up to now, I have been writing these articles for the DIYer ("do it yourselfers"), but this one is not going to be like that. This one is going to be different. This one is for the guy who is interested in what comes next, but will probably never use this information. This may also be for the person who is considering going into Home Automation as a business. It may also be for the person who already is in the HA business and thought that a "signal bridge" is all that he would ever need, that is, until he read my last piece. I suppose, that in all honesty, this one is for me. It will kind of act as a catharsis allowing me to vent some of my frustrations for all the times I have tried to explain to some "electrician" that 120kHz is not the same 120 volts.
Above all, this one is (TA DA!)...
Which One Should I Use, Part IV
(Complex Residential Coupling with Considerations for Dim/Bright)
My father used to say, "There are two kinds of people in this world. Those who believe there are two kinds of people in the world and those who dont". (You would have had to know my father to understand just how funny that really is.) Anyway, regarding X-10 residential systems, they also fall into two categories. Simple systems get by with natural coupling, a passive coupler or a single coupler/repeater. Complex systems dont.
You should have already read about the
variables concerning the simple systems but if you have not, I strongly suggest you go
back and read the prerequisite, "Which
One Should I Use, Part III". In that article, we discussed how signal travels
through a modest sized home using the standard 120/240v split-single phase distribution
system (see Figure 1) common to 99.99% of the homes in North America. (I know that since
"HomeToys" attracts readers from all over the world, I have to be careful to
qualify my statements.)
Before we move beyond the "simple" X-10 systems, we need to clarify a few points on the installation of both passive and active coupling devices. Figure 2 shows the basic installation of a passive coupler (ACT part number CP000, or the Leviton "signal bridge" 6299) which allows the X-10 signal to have a low impedance "short cut" from one leg to the other. As easy as this seems to be, there are many instances where even this can be misunderstood by the DIYer. First and foremost, by everything that I understand about the National Electrical Code (the NEC), the breaker panel is not to be used as an equipment box.
Therefore, placing the passive coupler inside the panel (as in Figure 3) is simply not acceptable. Now I know that most professional HA installers (and nearly all DIYers) simply toss the loose coupler inside the panel. I must confess that I, too, have done this in the past, but no more. The only exception I know if is when not doing so would constitute a larger infraction of the rules. (Now that is a whole article in itself.)
Figure 4 illustrates the accepted method which is to install a 2x4 wall box to act as
the enclosure for the passive coupler. Now look closely at the connection of the wires to
the breakers. Most breakers are
deliberately designed to allow only one wire to be connected to it. (Both you and I know
that if you twist them tight enough we can sometimes get them to slide in that little
hole.) A passive coupler (or, if you must, a "bridge") does not use any
electricity to work. It is, after all, a PASSIVE coupler. The requirement for breakers is
one of safety, they are not required to supply 15 amps of power. In fact, passive coupler
will pass no power at all, at 120v 60Hz. It will pass only the X-10 signal at a few
hundred milli-amps. If you are lucky enough to have 2 unused breakers, you have those
available for use with the passive coupler.
If you dont (Figure 5), and you still want to be code compliant, you may elect to use "doubles". Most breaker manufacturers make a double-breaker (we call them "skinnies" here in the midwest) that will fit into the space of one breaker but acts like 2 breakers (Figure 6).
Dont make the mistake that is often made by DIYers and even some electricians. They wire the double-breakers as shown in Figure 7 which causes the passive coupler to be wired from one leg and then right back to the same leg. That doesnt help much. Instead, the passive coupler needs to be wired as shown in Figure 8.
Okay, now we can move on to the next logical step. Lets discuss multiple panel, residential systems. Lets imagine a large "rich guy" house. (Ive worked on them, but I know that I will never own one.) Figure 9 shows a multiple panel system. This is somewhat simplified since I have seen some electrical distribution systems that looked more like a shopping mall than a house, but this one showing a main panel and 2 sub-panels will illustrate some basic concepts. Please ignore the "?#1" and the "?#2" boxes. I want you to pretend those arent there for a moment. That way I dont have to draw the whole thing over and over again.
Sometimes a single coupler-repeater is simply not strong enough to cover the entire facility. (If you are already lost and dont understand the concept of a coupler-repeater and didnt heed my suggestion to review "Part III", earlier, I strongly suggest you do it now.) Depending on the impedance of the electrical distribution system and the sheer size of the house, signals which originate at the main transmitter (which may be a computer interfaced, X-10 compatible device) are repeated by the CR230 at the main panel but are too weak to make it to the furthest points at one or both of the sub-panels. Now instead of a CR230, the house may have a Leviton 6201, but my illustrations will show the ACT repeater because I work for ACT.
If the repeater were to be moved to the "?#1" location (at the 1st sub-panel) it would greatly improve the signal strength on those circuits, but would most likely degrade the signal on the 2nd sub-panel so much to make it almost non-existent. Of course, moving it to the "?#2" position would result in a similar catastrophe. One possible solution would be to place a CR130 at each of the two sub-panel locations and eliminate the one in the middle. This "may" work. Let me reiterate that. It "may" work, but there are other factors at play that may cause problems. Lets say that the original signal from the main transmitter hits both of the repeaters at the same time. Both of them would "repeat" that signal at the same time. If God willin and the creeks dont rise, all the receivers on sub-panel #1 and sub-panel #2 would gets lots of signal. The problem is now the receivers that reside on the main panel. Some of them may also get the original signal from the main transmitter, but others will get signal "only" from the repeaters. The problem is that each repeater has its own 120kHz oscillator and so the signals will "beat" against each other. Dont think that if one is repeater is good, two repeaters are better. It is not like having two radios set to the same station. Instead it is like both your mother and father trying to tell you something at the same time. They both may be saying basically the same thing, but you get very confused trying to sort it out. This scenario is rare, but it does happen.
Lets use Figure 9 in another example. See that transmitter way down on a distant circuit from sub-panel 1? The one way down in the lower left? Lets say that you want the signal from that transmitter to control two different receivers, one is nearby on the same sub-panel, but the other receiver is way over on sub-panel #2. We are in what appears to be a no-win situation. If you have two CR230s installed at the sub-panels, they will "ping-pong" the same signal over and over for hours or even days and clog up the line so much that nothing else will work. Let me explain. The original signal from your transmitter (in the lower left) will cause the CR230 (position "?#1") to repeat. That "repeated" signal will then cause the CR230 in the other sub-panel (position "?#2") to repeat it again. The second repeated signal will then be repeated by the first CR230, which will be repeated by the second CR230, which will be repeated......well you get the idea. I have seen situations where it goes on all day before someone gets the idea to turn off the circuit breaker for one of the repeaters.
Perhaps you can avoid this problem by using Leviton 6201s instead of ACTs CR230s. It is true that they are designed (by X-10) so that they will not repeat previously repeated signal. Unfortunately, that causes another problem. When the original signal comes from the main transmitter (on the main panel) both the 6201s (at the sub-panels at positions "?#1" and "#2") receive the original signal at the same time and so both repeat at the same time, just like they were CR230s. Everybodys happy. But when the original signal begins way down there in the lower left, the nearby 6201 will repeat. The other one (right side) will not. That means that there will be insufficient signal for that receiver in the lower right on sub-panel 2.
There is a solution. (Let me draw a new diagram so you dont have to keep scrolling up to see the last one.) Figure 10 shows a CR231 on sub-panel #1 and a CR230 on sub-panel #2. The CR231 is a far more sophisticated coupler-repeater. It has many features which enables it to do some very complex coupling. It has (among its many abilities) a switch that will it allow it to either "ignore" previously repeated signal, or "repeat" previously repeated signal. Lets say that we have it set to "ignore" the signal.
Now, when the original signal hits both of them (the CR231 on the left and the CR230 on the right) both of them repeat at the same time. When the original signal is from that transmitter in the lower left, the CR231 repeats it, the CR230 repeats that but the ping-pong scenario is avoided since the CR231 will not repeat it again. Now this is not necessarily as easy as it seems since there is the risk of the signal from the second repeater "stepping on" (covering over) the next frame of signal from the transmitter, but that is too complicated to go into here.
Lets take a look at another feature of the CR231s that is beneficial when trying to control receivers on one distribution system, from a transmitter on a different distribution system. Figure 11 shows two separate systems. They could be two houses that are side by side or a house and a garage or any similar situation as long as they are not on the same transformer. Depending on the signal strength, overall impedance, plus other factors, it may have been possible to use some sort of passive coupling. Using two CR231s, however, is a sure-fire way of getting the job done. This is done by using one of the features of the CR231s which is the input/output of signal onto low-voltage wires. Using two-conductor, twisted pair wire between the houses, it is possible to send the signal which originates in the house on the left, over to the house on the right. There is no connection between the two electrical distribution systems and no need for conduit. The low-voltage wiring conducts a few volts of 120khz X-10 signal, not high voltage.
Any signal that originates on the source system is repeated by the CR231 on the left, plus the signals are sent to the target system on the right. Any signal that originate on the target system is also repeated by the CR231 on the right. If there are nothing but receivers on the target system, or perhaps, there are many buildings, or many "targets", it may be appropriate to use a true amplifier. The ACT CA000 is a true amplifier. Dont confuse it with the Leviton 6201. Leviton people often refer to the 6201 as a "signal amplifier" but that is (technically speaking) incorrect. A true amplifier adds power to an existing signal. The 6201 (like all of the eight different CRs designed by ACT) "repeats" the signal.
Figure 12 shows a CA000 "amplifier" block diagram. If you remember back to the previous article, I gave you the block diagram for a CR230. A coupler repeater can be wired into almost anywhere in a system because its input and its output are at the same place. It receives one frame of X-10 data and then turns around and repeats that frame of date out the same wires. An amplifier cant do that. Its input is separate from its output. It is like an audio amplifier where its microphone is separate from its output. If you get the mic too close to the speakers, you get feedback. The same will happen when a CA000 is incorrectly used. That is why it is seldom (almost never) used in a residential application.
As I look back over this article, I realize that in many ways, it asks more questions than it answers. It mentions more problems than solutions. It also fails to discuss the problem of repeaters and dim/bright commands. In "Part III", I promised that the elusive dim/bright/repeater problem would be discussed, but it is obvious that I didnt have room to include it. I will let you decide. The next section is scheduled to be on "Three and Four-Way Switches". After that, I promised to do one on "Noise and Filtering". If you want me to finish up the question of dim/bright and repeaters, please email me at firstname.lastname@example.org , and let me know your wishes. If I get enough requests, I will do it before the "Three and Four-Way Switches" section. If I get "some" interest, I will do it last. If I get no requests, I wont do it at all (and I will wonder if anyone is reading this stuff I write).
I also have another request that has nothing to do with X-10 or ACT or anything. I am constantly amused by the wide variety and wit some people show in their email signatures. I like to mentally collect some of the phrases I have read. Sometimes they make me smile, sometimes they make me think. If you have a particularly cute, thoughtful or unique email signature, or you have seen one, please email it to me. I would like to see it. Here are a few that I like.
"These are not the droids your looking for."
"Managing programmers is like herding cats."
"Jesus is coming -- look busy"
Thats it for this time. Depending on your emails, the next installment, may be called entitled...
Which One Should I Use, Part V
Which One Should I Use, Part V
As always, comments and suggestions are always welcome. Email me at email@example.com .
Phillip Kingery is the representative of Advanced Control
and teaches X-10 related classes around the country.
Upcoming classes include: Los Angeles, New York City and Atlanta.