I know there are different opinions but I’d like to hear from anyone who has experienced DCC problems that were solved by adding a snubber to the end of the bus.
Is there a designated distance before you consider adding a snubber?
I have two 30’ and one 20’ as well as a 10’ bus. Bus wire is 12 awg and it is twisted.
Your thoughts?
Are you having problems? If not, no need for snubbers.
The club layout builds to something like 28x154, maybe more now that some new sections have been added, big giant donut, 4 or 5 boosters. No snubbers. The only problem is some people type in the wrong loco address.
–Randy
Years ago, when I first installed a DCC bus on my original 5 by 12 foot layout, it did not work. I re-read the instructions, saw that a snubber was recommended, and put one in. No problems after that.
Mine is a Lenz system.
Thanks Randy, guess my 30’ is a non issue.
So are they related to the system in some cases?
I have NCE, I think Randy knows that.
From an electronics standpoint, it HAS to somewhat depend on just how the booster driver is made in each system. But how you run the bus probbaly has at least as much to do with it.
My previous layout was around a bedroom, figure on somewhere around 50 feet of single track main line. One booster ran it all, with the bus divided into two halves, one going clockwise and the other counter clockwise, each approximately equal in length at 25 feet. I had no issues, but I use Digitrax. I just tied off the free ends of each bus, they didn’t loop together (couldn’t, each was a different output off a circuit breaker) and the track didn’t loop together electrically either, there were gaps.
I’m not sure how long the bus runs are on the club layout (plus they vary, since it’s modular, some palces a short version gets set up, only a few places can the whole thing be set up). They aren’t as long as you might think based ont he size of the layout though, because the boosters are distributed around it, not all ganged in one place. Plus the main bus wires are twisted (sub bus is not, because it would trigger the block detectors) in wiring harnesses that run the length of each module and terminate at either end in Anderson PowerPole connectors. Also, the command station is never connected to the track bus, it functions as the command station only.
–Randy
Anecdotal evidence from the NCE and Digitrax lists on groups.io would tend to indicate they are.
On the NCE list, the topic comes up every so often. The thread usually goes on for days, with dozens of replies about needed vs. not needed, the values of the components, twisted bus vs. not twisted bus, how many twists per foot, 'scoping the waveform, etc. Observed from a distance, the first few days are usually fun, but it can only be argued so much before it stops being interesting.
On the other hand, on the Digitrax list it comes up much less often, and usually begins with something like, “One of the NCE guys at the club says I need snubbers, but I’m not having any issues. Why would he say I need them?” Then there’s maybe six or a dozen replies, mostly affirming that you don’t need to fix a problem you’re not having, and the thread dies.
I can’t comment on any other brands as I don’t follow any lists where they’re regularly discussed.
what exactly do people think snubbers do?
On my last layout, a fairly large one, I initially built it without snubbers. Then, on one of the technical forums, Wiring for DCC, some forum members made their case for snubbers, so I installed them every 12 feet. I had no problems before snubbers, noticed no difference in performance while the snubbers were installed and in place, then finally removed the snubbers when I noticed that they were hot to the touch. No noticeable difference in performance once the snubbers were removed. On my current layout, I have not bothered to install snubbers. By the way, I have an NCE PH-Pro 5 amp wireles system.
Rich
According to Mark Gurries, a snubber is used to remove unwanted signals on long bus wires such as noise, voltage spikes, etc.
Rich
We don’t need no stinkin’ snubbers here! [oX)]
I actually twisted my bus wires together, which seems to provoke controversy, and I haven’t had any problems.
Of course, with my knowledge of all things DCC, there could be a problem that I don’t even know I have. [:|]
As long as my DB150 beeps once when I turn on the power, my world is good. [(-D]
All of this is much UNLIKE our new wash machine. I can hear it go through all of it’s cycles on an AM radio. I know when the wash is done. [swg]
Mike.
I don’t think anyone anywhere recommended snubbers every few feet. You are supposed to use ONE, at the end of a bus line.
Based on the values suggested for components, the resistor needs to be more than your basic 1/4 or 1/2 watt type, it will pass a decent amount of current.
It’s supposed to be attentuating ringing and reflections, and supressing spikes above the nominal track voltage.
–Randy
Anyone? Anywhere?
If you read what Mark Gurries said, he mentions multiple snubbers. And, some years back, more than one thread on the Wiring for DCC forum talked about snubbers every 12 feet or so. Now, maybe that advice was overkill, but not knowing any better on such matters, I followed that advice. So, Randy, someone somewhere did indeed recommend multiple snubbers.
Rich
Note that ALL these recommendations, including twisting the bus wire, are generally for LARGE layout with bus runs of 30 feet or greater.
Frankly, I wouldn’t run bus wires more than 25 feet on my layout. That gives me 50 feet of coverage with the booster in the middle. That covers a pretty large layout. And keeping the runs shorter allows the use of smaller size wire with no issues.
–Randy