richhotrain bearman Ok, what's a snubber? I googled it and got back all sorts of electricity mumbo jumbo that is above my pay grade. And what are the symptoms of any problem that can be traced to the lack of a snubber? And, would I need a couple? I have two 14 gage busses, about 20 feet each, feeding two power districts and I just terminated them at barrier strips. My current layout operated just fine without snubbers, but after a heated debate on the Yahoo forums a few years back, I decide to add snubbers. I saw no difference in performance. So, on my next layout, I will skip them. Rich
bearman Ok, what's a snubber? I googled it and got back all sorts of electricity mumbo jumbo that is above my pay grade. And what are the symptoms of any problem that can be traced to the lack of a snubber? And, would I need a couple? I have two 14 gage busses, about 20 feet each, feeding two power districts and I just terminated them at barrier strips.
Ok, what's a snubber? I googled it and got back all sorts of electricity mumbo jumbo that is above my pay grade. And what are the symptoms of any problem that can be traced to the lack of a snubber?
And, would I need a couple? I have two 14 gage busses, about 20 feet each, feeding two power districts and I just terminated them at barrier strips.
My current layout operated just fine without snubbers, but after a heated debate on the Yahoo forums a few years back, I decide to add snubbers. I saw no difference in performance. So, on my next layout, I will skip them.
Rich
Short verison:
A snubber is component (capacitor + resistor) that filters out noise on the DCC bus. Some layouts need them, others dont.
Better explaination than DCC wiki here:
https://sites.google.com/site/markgurries/home/dcc-general-best-practices/wiring-planing/snubbers-rc-filter
Thanks, Randy, that helps.....a lot.
Alton Junction
If you have plenty of feeders, #14 plus Code 83 rail probably gives a #12 or better equivalent. It’s when you run down to the far end without feeders to drive a breaker or a reverser, or you put the breaker next to the booster and then some lines go a short distance to the closest power district and others run all the way down to the end with no feeders because that run is passing a different power district to get down to the one it powers. Running light loads, you won’t see a noticeable drop - 2 or 3 sound locos consisted is still under 1 amp so a tenth or two drop over a long run. Worst case would be power at one end of an 80 foot layout. That’s 160 feet of wire, and it wouldn take much current to get a noticeable voltage drop.
Just running a train around, with less than half a volt drop, you’ll never notice it. Even more, you may not notice it but the train will be slower if there is a 1 volt drop relative to track closer to the power source. It doesn’t go instantly from one speed to a slower speed, the speed gradually changes as the loco gets further away and then comes back towards the supply.
You can measure it, but you need a load - the 10 meg impedence of a digital meter means it will have little effect on voltage and it should be the same everwhere. But put a 2 or 3 amp load across the rails and check again. If the bus is insufficient then you will measure a voltage difference from right next to the supply to the furthest point.
if you had say a 50x100 layout and tried to run just a single bus because you never run enough trains to need more than 5 amps, even #10 might not be enough. That’s why how many boosters you have isn’t just dependent on the number of trains being run. On a large layout, you can distribute the boosters so there are no long bus runs and #14 is fine, and wire them via the systems control bus which, because of low current draw, doesn’t drop much voltage and even if it did, so long as the booster gets something above the threshold it needs to distinguish a 1 and a 0, it will work fine. The level of the control input does not determine that level at the track outputs.
—Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
rrinker richhotrain rrinker Witht the length of layout it probably needs #12. I have a difficult time believing that a home layout needs 12 gauge wiring. What is the issue? Voltage drop? Rich Yes, voltage drop. If this layout really is 80 feet long, and the power source is in the middle, that's a 40 foot run either way. 80 feet for a complete circuit to the furthest position. That much #14 is nearly a full volt drop at 5 amps, so it's 1/2 amp or worse even at less than full load. I did use #14 on my previous around the room layout, but the logest run from the power source was no more than 20 feet, 40 feet for the complete circuit, half that of this example. And my layout wasn't emulating a 4 track PRR main line which you might expect to have at least 4 locos running at the same time. My whole layout could handle maybe 3 trains max, and that's spread out across 4 power districts, not all on one bus. If built according to my post, with 2 boosters each at 1/4 points, that makes the max of any bus run 20 feet, so #14 will be fine. --Randy
richhotrain rrinker Witht the length of layout it probably needs #12. I have a difficult time believing that a home layout needs 12 gauge wiring. What is the issue? Voltage drop? Rich
rrinker Witht the length of layout it probably needs #12.
Witht the length of layout it probably needs #12.
I have a difficult time believing that a home layout needs 12 gauge wiring.
What is the issue? Voltage drop?
Yes, voltage drop. If this layout really is 80 feet long, and the power source is in the middle, that's a 40 foot run either way. 80 feet for a complete circuit to the furthest position. That much #14 is nearly a full volt drop at 5 amps, so it's 1/2 amp or worse even at less than full load.
I did use #14 on my previous around the room layout, but the logest run from the power source was no more than 20 feet, 40 feet for the complete circuit, half that of this example. And my layout wasn't emulating a 4 track PRR main line which you might expect to have at least 4 locos running at the same time. My whole layout could handle maybe 3 trains max, and that's spread out across 4 power districts, not all on one bus.
If built according to my post, with 2 boosters each at 1/4 points, that makes the max of any bus run 20 feet, so #14 will be fine.
--Randy
Let me ask this. Will a voltmeter show this drop on a DCC powered layout? Must the voltage be measured under load? Will voltage drop occur on longer bus runs in spite of adequate feeders along the entire bus wire run? If 12 gauge bus wires are required for runs longer than 40 feet, at what length will 10 gauge bus wires be required?
Marvelous, Rich, thank you. I can now continue in blissful ignorance of electricity mumbo jumbo.
Bear "It's all about having fun."
Thanks, carl, but it is still electricity mumbo jumbo.
bearmanOk, what's a snubber?
https://dccwiki.com/Bus_Termination
I have the right to remain silent. By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.
Witht he length of layout it probably needs #12.
Though I think the main system plus one additional booster would be plenty. But I wouldn't place them next to each other in the middle - I'd place them at the 1/4 points:
|----<booster>----<gap>----<booster>----|
(yes, the number of - I typed matches)
That makes each bus run no more than 20 feet, if the entire layout is 80 feet long. #14 might be ok then. 20 feet of wire shouldn't need a snubber, or every 4x8 layout would need them.
I see that a few replies recommend 12 gauge bus wire.
If this is an HO or N scale layout and a 3 to 5 amp DCC system, do you really need 12 gauge bus wire? That seems like overkill to me. I have a similarly sized layout to the OP and 14 gauge bus wire is quite sufficient for my 5 amp HO scale layout.
This thread isn't all that old, but the OP never replied to the posts that were made in April and May, so maybe he has had his questions answered.
I think that BMMECNYC brings up some important questions the answers to which will inform any answers for the OP. However, if you are using the 5 AMP NCE system, I don't think that a booster is required regardless of scale, assuming you are not going to load up with accessories.
Number of boosters:
How many sound equipped locomotives will you run simultaneously? How many non-sound?
What is the topography of the layout?
What scale? No one asked this and its kind of important for posterity to have it in this thread. I dont recall what scale you are modeling in.
How long are your trains?
Might you wish to add signaling and resistor equipped wheelsets to your layout later?
What system are you using currently, the PH-pro (5amp) or the Power CAB (2 amp)?
I don't see the need for two boosters. The NCE Command Station that came with the 5 AMP Power Pro system runs my entire layout, ~200 feet of track.
I would put a booster in the center of the dogbone. The track feed from the booster would go to two breakers. Each breaker would feed one end of the dogbone. Make sure each end of the dogbone is electrically insulated from the other end. The breakers can be mounted anywhere it's convenient.
Number 12 AWG wire is recommended for the main bus.
The snubbers are installed at the end of a buss run. You would need two, one at each end of the dogbone.
1) I'd just run a single "booster to end of layout" bus down each leg, then tap off it at the appropriate spots for the breakers. I'd probably also bump up the gauge of those "main busses" to 12 awg instead of 14 awg.
2) See above.
3) Probably, since you're using NCE.
I have two reversing sections, old PS-REV (DCC Specialties) boards that still work fine. For no reason in particular, I mounted them near the track sections they control.
Later, I sub-divided the layout using the two reversers and a PSX-4 (DCC Specialties) The PSX-4 is 4 breakers mounted side by side on a single circuit board. It's easiest to leave the board as one and just run short jumpers to daisy-chain the inputs. I put that close to my base station. I left the reversers where they were and ran separate power lines from the base station to them.
Either way, it seems to work fine. They are attached to the wood cross-pieces of the benchwork, beneath the pink foam sub-roadbed.
Each of these circuits has indicator LEDs which can be made remote. I should have done that, to bring them out to the front of the benchwork and make them easily visible without bending over to see them under the layout. It's one of those things you put off when building the layout so you can just get trains running.
It takes an iron man to play with a toy iron horse.
Layout is a dogbone with about 80' of track between the return loops. Loops will be staging at either end probably three tracks of reach of two tracks. Layout will be four tracks wide (PRR). all 4 will be wired so trains can cross all four tracks for switching. end loops will have reversers. so here are the questions:
1. Intend to place NCE DCC base unit app, at the middle of the 80' and run a main bu for each half of the layout with its own booster (2 total). each half will be divided into 20' blocks with circuit breakers plus the loops making 6 total. do te circuit breakers go at the block they control or near the base unit?.
2, If near the block I assume i am pulling a parallel bus from the main for the block. should it be seperated by any distance from the main bus other than the connection?
3. Do I need a snubber on the blocks or main bus terminations?
Thank you.