I ran upon this item during my internet searching the other day and wanted to know if any of you have done this or heard of it, and what do you think of it? This was from a mrr supplier in Australia and this is a cut and paste from their site (I didn't copy their name but I think it was a Flicker Free Lighting manufaacturer?).
The company sells these for $10 a pair but give the instruction above to make your own.
Life is what happens while you are making other plans!
How big is your layout? Mine at about 9x15 + a little isn't nearly large enough to have signal problems that would require the filters.
Our modular club layout, when fully assembled (only 1 venue we go to twice a year can handle the entire system set up) is 20x140 or so and it has no operational problems with DCC that would require the filters.
From a technical standpoint they do SOMETHING, other sites have posted scope traces with and without the filters. The key issues though seems to be that the DCC design is robust enough to work without the terminator filters on the end of long wire runs.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Some of the earlier boosters would spike and corrupt the square wave DCC signal. Early Wangro and CVP and very large Digitrax systems were prone to spikes as high as 50 volts. Twisting the buss wires would help and making sure the cab buss was separated by at least 3 inches helped as much as buss terminators did. All of the latest or I should say after the first generation of boosters have built in terminators. Basic wiring principles should always be used. Large enough wire to handle the load going through it and on long runs four to five twists per foot would be good.
http://www.wiringfordcc.com/dcc_waveforms.htm
This is an old link but still very useful.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
Thanks guys, I was just curious about this as I haven't seen any mention of it on this forum or in any of the DCC books and reference materials that I have. I am new to DCC (about 3 weeks into DCC and loving it!) so I tend to look at everything that might help with a more 'bullet proof' layout.
BTW I just installed my third decoder and it is really not that hard on some of the locos that I have.
Bob
I've never seen them needed. Termination certainly won't hurt. It can be built with < a dollars worth of parts. I certainly wouldn't pay $10 for one. Termination seems to be discussed more on the NCE forums. When the bus gets to a length that may require termination, you are also getting to the point that a slave booster could be needed. The bus length starts all over again from there.
There is the issue of signal "ringing". This happens with very long runs of bus wire when there is no load on it. Don't know if this is the same as the spiking issue or not. It looks really interesting in theory; however, between the large layouts of two clubs, a museum, and three different modular groups I have yet to encounter a layout that has really had the issue. From my own limited experimenting it appears the first locomotive placed on the track works just the same as the terminator. I keep wanting to do a more complete science project on it but never find the time.
The ringing is exactly what is being referenced. It seems to be there, if you scope the lines, but the question is, how bad does it have to be for it to actually cause a problem? Also, you could theoretically get reflections off the open end (think antenna and SWR) if the bus is just the right length. Our track bus is NOT looped, it does 'end' at certain modules, so it is a long 'straight' run, although there are multiple boosters to power it all.
But - experience in a large club modular layout says this isn't a problem, at least not for our system (Digitrax) with #12 bus wire and powerpole connectors between modules. Next year we should have enough additional modules to hit 200 feet if they are all used - we'll see then.
I've wired a large HO scale layout (20 x 40 feet in one room and 20 x 15 feet in a second room) using 18 Gauge speaker wire and did not install any type of termination on any of the bus wiring.
The layout is divided into four power districts with separate boosters on each. We are using the NCE PowerHouse Pro with ProCab Radio throttles and have had no ringing problems anywhere. NCE does not even mention the use of bus terminations.
thanks for all your input on this. I gather from your commnets that it is something I shouldn't worry about. Being new to DCC I am looking at everything I read about and want to make sure I have all the bases covered. My layout is 18' x 22' and I am just getting ready to install my bus wiring.
It's definitely nothing to worry about unless you were experiencing problems with a large layout.
Springfield PA