Bachmann Online Forum

I want to double check what I believe I read in the Forum:  I am switching a DC operation to DCC.  I currently have about 9 blocks.  While blocks are not necessary in a DCC operation, there is no physical reason I need to remove the block controls (plastic rail joiners and wiring).  And it may be advantageous to have blocks if a short occurs?  I am going to also throw in a question about turnouts:  remote control turnouts I have currently will work just fine using a separate AC hookup to one of my DC power packs.  Sorry if this question has been asked and answered.  Thanks.

Replace the DC power pack with your choice for DCC system and set all blocks the same and you are ready to test  You will quickly find out if the present track wiring is good enough for DCC and if additional power connections are needed.

You should be able to continue to control the turnouts as is.

Thanks.  What I am still unclear on, is do I need to replace all the wiring from my controller to each block, with a heavier gage wire? I believe I used 22 gage wire.  Should it be replaced with 16or 18 gage wire?  And what does "bus" stand for?

The NMRA says to use 18 gauge wire for HO and smaller scales.

"Bus" is a contraction of the Latin word omnibus.

Wiring in DCC sounds a lot more complicated than DC.  Do you think using the 6 blocks I have on my small 4x6 layout, I will have a good enough power distribution? Or will more feeder wires be necessary?

Personally, I think DCC simplifies the wiring:  Left bus to left rail, right bus to right rail, and reverse loop modules take care of shorts for uninterrupted running.

Which DCC system are you using?

How many locomotives will you be running at once and do they have sound?

How are the feeder wires currently spaced?

Thanks for replying again. I have a small n scale layout, 4x6.  simplified it is inner and outer loops connected by turnouts; I have several sidings off of the inner loop.  I have broken this layout into 9 separate blocks, controlled by several Atlas selectors.  I can currently run 2 trains via a 2 cab set up.  My confusion comes from reading the frequently DCC may require for feeder lines.

I recently purchased an NCE Power Cab system.  At this point I am expecting to run 2, possibly a 3rd loco in time.  Since I am new to DCC my first 2 locos will not have sound.

I don't have evenly spaced feeder wires.  I have  assumed the feeder wires to the 9 blocks serve the purpose of adequately distributing power.  From your previous post I understand that I can keep the blocks but may need to change the gage wire from 22 gage to 18 gage.  Hopefully I have helped in giving a better understanding.

I also use the NCE Power Cab system.

Ideally you should connect a feeder to each rail segment, but my On30 E-Z Track layout has feeders every 3-5 feet along a 90 foot bus, and the Power Cab has no trouble keeping up with that length.

Non-sound locos tend to draw half an amp to a whole amp when active, and the Power Cab can handle up to two amps at a time, so you shouldn't need a booster.

You can remove the blocks to simplify the wiring if you like, or rewire them so they control individual sidings so you can 'turn off' locomotives to save power.

For the size layout you are describing and the number of N scale locos you say you will run, the Power Cab and 22 gauge feeders should work OK.  I have basically done the same thing with Kato sectional track and their feeder wires (24 gauge) without using a bus when I set-up temporary track arrangements.

One thing to be aware of is that this might cause the electrical resistance to the location of a distant short circuit to be too much to allow enough current to flow to cause the Power Cab protective breaker to trip.  So, if that is the case, and you get a short circuit at that distance from the Power Cab, you would get a continuous current of up to somewhat less than 2 amps through that short circuit.  That could eventually cause a lot of heat build-up at the location of the short circuit contact, and that might melt plastic parts and/or damage electronics.

The "quarter test" that you have probably read about in model railroad wiring publications is basically a test to see if that can happen.  By using a quarter (or anything else) to deliberately create short circuits one-at-a-time all around your layout, you can find any places where the track power breaker does not trip.  If you find such a place, and that section of track is fed directly, then you know that you need heavier gauge wire feeding that location.  On the other hand, if the rails at that location are fed only by rail joiners to other sections that are fed directly, then adding a new feeder to that point is probably needed, although you might be able to just solder the linking rail joiners if they are not already soldered and have corroded a bit over time.

One thing to understand about the Power Cab is that it has a lower circuit breaker trip current setting (somewhat less than 2 amps) than most DCC circuit breakers that can be bought separately.  That includes NCE's EB1 breakers.  The PSX Power Shield breakers do have adjustable setpoints that allow current trip values as low as 1.27 amps, so that it would just barely trip before the Power Cab.  but, that really doesn't do much with respect to lowering the threat of an uninterrupted short circuit.

Still, the Power Cab current rating is not as dangerous to your equipment as a 5 amp system. If you are watching your trains, then you can probably notice and clear a fault before anything melts.  On the other hand, if you like to just let trains run in circles while you may be distracted, then you are probably asking for trouble with track sections that will not trip the protective circuit.  The most dangerous locations would be switches ("turnouts") that cannot trip the breaker, because that is where most short circuits are going to occur.

I know the answer to this one.  :) This is what I did:

1. Disconnect all of your DC power packs from the track wiring and don't connect them ever again (unless you wire in a DC/DCC switch, but that should be connected in such a way that when the switch is thrown to DCC it disconnects all DC power packs from the track wiring. You do NOT want to have the DCC and DC power packs hooked up to the track wiring at the same time, bad things will happen).

2. Hook your + wire up to the Cab A connection on your control panel and the - wire to the common rail.

3. Throw all of your block switches to Cab A.

4. Run two trains at a time with a big smile on your face, but be aware, you can now crash them into each other so you will really want to be aware of what your turnouts are doing...just as if you were driving a real train.

If you ever want to get away from using the DC packs for turnout power NCE makes a device called a Snap-It that uses track power to switch the turnout directions, you can wire it in with the Atlas turnout control or operate it from your NCE hammer.

Thanks to everyone who has offered help.  I spoke with a tech person from NCE.  Really helpful person.  I've decide to remove the old block system, and run a bus line with feeders @ every 3 feet.  I will use 14 awg for the bus and 22 gage for the feeders.  One question I still have is:  a preliminary marking of feeder points from the bus line, show that the spacing can be a little more than exactly 3 feet.  I am assuming that +- a few inches will not be significant.  Also if I reuse existing wires for feeder lines can I get away with 20 gage vs 22 gage? Is it dangerous or does it create a potential problem if feeder wires are a mix of 20 or 22 gage? Thanks again for any additional help.

The 3 feet spacing of feeders connection to track came about in part because a HO flex track section is 36 inches long. This eliminates depending on rail joiners to carry DCC power.  Same thing can be accomplished, close enough, by soldering the rail joiners if feeders spacing is more than 3 feet.

Ideal -  Rule of Thumb - feeder is connected to each rail at the center of a track piece so there is equal distance to the rail joiner at each end. This is not always practical so close is good enough.   This center rule of thumb is not applicable to turnout wiring.
 
The voltage and amps the wire is required to carry determines its gauge and maximum length.  Keep feeders length about 12 inches or less you can mix the use of 20 and 22 AWG wire for feeders just do not use 20 to one rail and 22 AWG wire to the other rail on same track piece.

I'm new to this could some one show me a picture of how your doing your feeder wires on EZ track. Just got started on my n scale ez track layout. I too am wanting to go DCC. Thanks for any help.

There is really a lot of flexibility in how you do feeders.  So, no need to obsess on  getting exactly the same spacing between connections from the bus to the track, or even using the same gauge wire for all connections, or even to the opposite sides of the same connection point.  (I have no idea why Hunt thinks that you should not use 20 gauge to one rain and 22 to the other - unless 22 is too small for the connection, it doesn't make any difference, because the current flows up one and down the other, then reverses if DCC.)

Regarding soldering rail joints.  It is not a bad idea to solder most rail joints.  But, you don't want to solder all rail joints because that removes their ability to let the rails slip in an out as the wooden platform expands and contracts slightly with changes in humidity over the year.  Completely rigid rails lead to kinked straight track and/or curves that are pushed off the roadbed.  Typically, people solder the rail joints on curves to make sure that the curves don't kink at the joints, and leave unsoldered joint on the straight sections between curves at intervals of six feet or so.  If you manage to get a feeder wire attachment to every piece of track, then it is not really necessary to solder any rail joiners from an electrical point of view - but you would still probably want to solder the joints on curves from the mechanical/kinking point of view.

Maletrain thanks again.  My bus wires are running parallel (of course) around the layout. Is there any concern if the bus wires touch or do they need to be separated a certain distance.  I am not planning to  twist them as I saw in some videos.

Bigal232 - search YouTube. There are numerous helpful videos.

Quote from: Fish on February 05, 2019, 12:43:32 PM
Is there any concern if the bus wires touch or do they need to be separated a certain distance. 

My layout actually uses lamp wire for the bus, I don't have issues with cross-talk.

And the rails aren't spaced very far apart either, you shouldn't need to worry.

Flare,  I know the standard advice,which is to twist the bus wires about 3 turns per foot to avoid signal distortion and interference.  But, I really don't know how important that actually is for smallish layouts.  I know that NCE recommends that the cab bus and the track bus wires not be run close to each other to avoid cross-talk, even when twisted.  Those two buses are carrying different signal "traffic".   For a shelf layout, they recommend putting the cab bus along the front edge (so that it can have places to plug-in throttles) and the track power buses along the back edge.  That would seem to imply that the track power buses (that all carry the same DCC signals) can run parallel for whatever distance is needed to get a bus to a distant power district through another power district that is between the command station and the more distant track power district.

Working on installing bus and feeders.  I thought I would fire up the Power Cab, as per directions.  I also hooked the track wires into the power panel.  I had feeder wires  hooked up to one section of track.  However I was unable to detect any voltage.  So I checked voltage at the power panel wire "do-hicky" connector.  Again I was unable to detect any voltage from the track wire connection.  What am I missing regarding voltage? Is it possible the voltage meter will not read low voltages.  It only has 2 ranges, 700 and 200v.   I am using wire connectors from bus to feeders. The cab powered up as it should.  Power to the cab but not to the tracks. I will contact NCE tech support but maybe there is a simple fix or explanation other than it's defective.

Are you setting your tester for DC or AC?

DCC uses a digital wave form that mimics AC.

System connected properly?
Looking at PCP (Power Cab Panel -  aka Power Panel)  with Red LED on bottom
Power Cab >>Flat cable >> left socket of the PCP(Power Cab Panel)

Voltage on track
Read using meter AC setting
Power output to track is full voltage PWM alternating DC waveform seen by meter as an AC waveform,  about 13.5 VAC , 5,000 to 8,500 Hz
Your meter set on AC is calibrated to read 60 Hz sine wave AC so you will not get an accurate reading.

Yes I am using the AC setting on the meter.  All plugs in proper place. The Cab is reading as per the manual.  I had placed a dcc on board diesel on the segment with feeder wires attached.  Initiated programming as per manual but got no indication of power to track.

Re Hunt comment:  You said my meter would get an inaccurate reading.  I am getting no reading.

Fish,
When using Program Track (page 46, Power Cab System Reference Manual. Rev. 1.65) there is no voltage sent to track by Power Cab except for very brief moment a command is set to decoder. Your meter will never show this as time frame too short.

*** edited ***

Fish,

When using Program Track (page 46, Power Cab System Reference Manual. Rev. 1.65) voltage to track is  turned OFF by Power Cab except for a very, very brief On  moment, then back OFF as a command is sent.   Meter does not display any track voltage when using programming track mode as time voltage is On is too short.

Can your meter display 12 to 13.5 volt AC?

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Place a DCC equipped locomotive on track and turn on power to the Power Cab Panel. After the Power Cab system start up sequence is complete -- can you toggle locomotive headlight On and OFF by pressing HEADLIGHT button? If not, recheck all the wiring.

Quote from: Hunt on February 07, 2019, 12:00:49 AM
Place a DCC equipped locomotive on track and turn on power to the Power Cab Panel. After the Power Cab system start up sequence is complete -- can you toggle locomotive headlight On and OFF by pressing HEADLIGHT button? If not, recheck all the wiring.

Fish........You do know --- you have to SELECT LOCO before you can turn its headlight On and Off

If not, follow Quick Start page 1 of the Power Cab System Reference Manual. Rev. 1.65

In other words,
While not an accurate measurement a multimeter, even a cheap one like a Harbor Freight 7 Function Digital Multimeter  free one with coupon,  set on AC volts to read DCC track voltage can be used and is usually good enough. In fact it is more accurate reading DCC than some expensive True RMS multimeters.

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The technical stuff
The commonly found multimeter is designed and calibrated to measure an AC sine waveform in the 50-60 Hertz range. DCC is not an AC sine waveform but an alternating DC (yes – DC) waveform containing digital information and is a higher frequency.   DCC is bipolar pulse-width modulation (PWM) DC (direct current)  waveform.

My appreciation to those who have offered advice.  The problem has been corrected at least to the point of getting power to run my DCC ready loco as far as I have feeders connected.  I do have one of those HF "cheap" multi-meters but once I saw I had power checking track voltage became less important. To Hunt: mistake was my brain not registering what my eyes were seeing.  Once both of them were working together it was an easy fix. 

Quote from: Fish on February 09, 2019, 12:48:11 PM
. . . .  The problem has been corrected at least to the point of getting power to run my DCC ready loco as far as I have feeders connected. . . . .

What are you using to run the locomotive? A NCE Power Cab will not run a DCC ready locomotive.

DCC ready is short for 'DCC ready for a decoder to be installed.'

DCC Ready means the motor brushes are isolated from the power pickups and there is some means, a socket, solder pads, wires or something else, to accept the installation of a DCC decoder.

Another way to look at DCC ready - once a DCC decoder is installed the only electrical path to the motor is through the decoder.