Follow the recommendations of the manufacturer of your DCC system. If you don't have DCC, forget about it.
Dante
We don't use them on our HO scale club layout that uses the NCE PowerHouse Pro system with radio throttles. Our main layout room is 20 x 40 feet, and the layout extends into a second room that measures 15 x 20 feet. All this is powered from one main DCC Command Station and 3 additional boosters. We have never had a need for snubbers.
I use them, and my bus wires run 90 feet in each direction. I place them at the ends of the bus wires.
Some people call them bus terminators, but the proper term is RC Filter, as I understand it.
I have been told that the main reason for snubbers is to dampen voltage spikes to avoid frying decoders.
My snubbers are each made up of a 100 ohm 1/2 watt resistor and a 0.1µF 250V 10% metal-film capacitor.
Rich
Alton Junction
These are for DCC beese. Older network topology required such a device otherwise spurious singal would echo in the bus. Nost network technology (Cat-5 etc.) do not require end of line devices (snubbers) since there is only one pair of devices on the wire. Not so a DCC bus, but my understanding is that most DCC systems no longer require this.
LION does not do DCC, but him has strung miles of Cat-5.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
If you have a long buss run and are having trouble with engines losing or not getting their commands, a buss snubber might help the problem.
Are they necessary ? I would say no - unless - you are having trouble, then it might help. I know a LOT of people running DCC and on some pretty large layouts .... nobody I know are using them.
Mark.
¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ
This was recently mentioned in " general discussions" What is their purpose and are they necessary ? If so how many are needed. Thanks.