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Do sub busses need snubbers as well?

 

I'm planning on using a single wire sub bus for signalling and block detection purposes consisting of 12 AWG stranded wire.? The blocks will be from 18' to 30' and fed by either 10 awg or 12 awg main busses.? Due to the length of my main busses being between 30' and 40', I will be using snubbers on the main busses.? Does this single wire sub bus need to be addressed?? I'm using a 10A system for O scale.

Mike
 

Any DCC signal bus 30 or more feet long is likely to operate erratically if it doesn't have a snubber. YMMV, but good practice is to add the snubber.

Don W

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Don Weigt
Connecticut
 

Mike, placing a snubber at/on the track end of a current based occupancy detector is problematic. So I would say no. It is not really a sub buss unless you run both wires as a pair all the way out to the track.

DonV
 

How all. What causes a short at the gaps from crossing over from one to the other district . You see the train stop on the gap with arking on the wheels at the gap. Till the booster resets till the next engine come to the gap.and it will do that till each train engine is past the gap or you have to pull them through.? what is wrong here. And how to fix. All wire are correct red to a black to b on both sides of the gap . We had the same problem on distric 2 so to salve that we got rid of distric 2 .now distric 1&2 are 1 distric run by the camand station db150.? distric 3 which is now district 2 run by db210 booster also changed the loco net cable it's good o.k so. That's are debunk


On Tue, Oct 31, 2023, 9:06 AM Don Weigt, <dweigt47@...> wrote:
Any DCC signal bus 30 or more feet long is likely to operate erratically if it doesn't have a snubber. YMMV, but good practice is to add the snubber.

Don W

--
Don Weigt
Connecticut

 

Don V shares:

"Mike, placing a snubber at/on the track end of a current based
occupancy detector is problematic. So I would say no. It is not really a sub
buss unless you run both wires as a pair all the way out to the track."

There's a good illustration of this at:


Note the verbiage about _not_ twisting those local block buses due to the
potential for triggering the current detectors.


Note the following:

1) No snubber between the block detection device for that block and the
rails,
2) All track feeders for a given block go to the local block bus first,
3) Only one set of feeders runs from the block bus to the main bus, and
4) There is a snubber at the end of the main track bus.

If given the nature of the OP's long blocks, and the need to avoid twisting
the block bus so as to not trigger the block detectors, if the layout
experiences noise on the track bus, additional snubbers can be added along
the main bus to assist in the suppressing of interference/noise. It's not
_mandatory_ they be at the end of the bus, though that is by far and away
the best location. Add these additional snubbers on the main bus only as
needed to clean up the signal.

_IF_ you're having performance issues try additional snubbers.

_IF_ not, don't.

Best regards,

Steve

Steve Haas
Snoqualmie, WA
 

Thanks Don.? And thank you all for your comments.
 

Thanks Steve.? I had read that document on more than one occasion and forgot about that note regarding the snubbers on the OD bus.? Thanks for bring that to my attention again!

Mike

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