Re: Bus Length

Steve Haas

>>>> My question is: if you add a sub bus for occupancy does that affect the total length of the control bus? <<<<

      That would depend on where you connect the sub bus to the track bus.  If you connect a 10 foot sub bus to the end of a 40 foot bus you have an effective run of 50 feet.  If you connect a 10 foot sub bus to a 40 foot bus just 10 feet from the booster you’ll only have a 20 foot run to the end of that sub bus.

>>>> AT 5A I will be pushing the total length of bus runs at 36-40ft. <<<<

      I’m curious as to where you got those specific limits.  The primary concern with long runs is voltage drop, this can be remedied to a point by using heavier wire.  The other concern is that the longer a bus run is the more likely the layout will have to deal with inductances issues.  These inductance issues can be greatly reduced by twisting those bus wires three to five times a foot.  If needed, a RC snubber can be added.  The other thing to remember is that a bus can go in two directions.  Placing a booster at the beginning of a 60 foot run might cause you some problems – placing that booster in the middle of that run results in two 30 foot runs – half the distance, half the problem.

>>>> From what I am reading if i add an RC filter and use 12ga solid wire I should be OK, unless of the course you need to add the length of the sub-bus to that total. It seems to me however that it is running parallel to the main bus. <<<<

      Filter won’t hurt.  For our purposes dealing with DCC power and data packets, there’s no difference between using solid and stranded wire of the same size.  With regard to total bus length, refer to my comments above; effective bus length = distance from booster to connection with sub bus + plus length of sub bus.

      Any questions? Give us a holler!

      Best regards,


      Steve Haas

      Snoqualmie, WA

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