# Question - AC or DC



## mopac (Feb 24, 2011)

If I wanted to test track voltage, using DCC, would I set meter to
AC or DC? Thanks for any info.


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## gunrunnerjohn (Nov 10, 2010)

Well, that's an interesting question. The voltage on the tracks for DCC is AC, but it's probably not going to get a valid indication on anything but a true-RMS meter, since it's not a sine wave.


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## tjcruiser (Jan 10, 2010)

Exactly. It's a step-wise square wave, with a variance in the spacing between +/- voltage pulses, which contains the coded info sent to loco decoders. A good layman's description here ...

http://www.loystoys.com/info/how-dcc-works.html

TJ


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## NIMT (Jan 6, 2011)

True digital RMS meter set on AC will give you the most accurate readings on DCC.
Max voltage for HO is 15 volts.
Output from DCC unit or track voltage is based on system and input voltage, I run mine on a 28 Volt DC power supply, and get 15 Volts output, minimum must be greater than 12 Volts AC or DC input to most systems.


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## mopac (Feb 24, 2011)

Thanks guys. That helps. I thought it was more of an AC current.
I am not electrically enlightened. Far from it. I have a cheap multi
meter so I am sure it is not the RMS type. Although the article TJ
posted said an AC meter would give a close reading. Not 100% true
but close. I am running DC on my 4 x 8 layout but do expect to start
a much larger layout sometime soon and it will be DCC. I am in the 
stage of running questions in my head. I have been away from model 
trains for about 10 years. DCC is new to me. I have purchased 2 DCC
engines this year (with sound) so need to get this started. Thanks again.


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## gunrunnerjohn (Nov 10, 2010)

FWIW, a true RMS meter isn't all that expensive, nice thing to have.


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## NIMT (Jan 6, 2011)

mopac,
I have been doing DCC for over 15 years and I never check voltage on the rails. DCC is pretty definite it either works or it doesn't. Voltage is not a big worry it's amperage that can get you into problems!
What DCC system do you have or are you going to have?


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## mopac (Feb 24, 2011)

I have been shopping for a digitrax super chief 8 amp. It might be 
a little over kill but maybe not. 8 amp is only about 20 bucks more
than 5 amps so why not. About 1 1/2 miles from the house I have 
the UP and BNSF mainlines. Both are double tracks and at one point
are only about 300 feet from each other. Different levels. I call one
the high tracks and the other the low tracks. My layout will be a loose
representation of this area. I can go 24 feet long with the layout. It 
will be a dog bone. So with 4 main tracks I might have 4 trains with consists
of 3 engines each. I know 12 engines need lots of amps. I hope 8 amps
will do it. HO by the way.


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## NIMT (Jan 6, 2011)

Mopac this is too funny,
I have UP's main line bordering my property and 300 feet west of that is BNSF's double main and a maintenance spur.
I have a Digitrax Super Chief DCS 200 8 amp, along with a few DB 200+ 8 amp boosters. It's never overkill to have too many amps. Get the new 20 amp PS2012 power supply too, it's so worth it! I run mine off of an old telephone system transformer thats output is 28 volts DC and 35 amps. I've got 8 amp circuit breakers on each of the 8 amp units.
8 amps will run that many loco's. my best run was 4 DD40's with twin motors, 2 SD70M's 4 U30C's 1 U23B and a 44 ton switcher all running at the same time without overload. Proper wiring is a key with the large amp system, I use #10's for my bus line and #18's for my drops, I stick with 3 feet or less on the drops.


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## mopac (Feb 24, 2011)

Sean, that is the power supply I have penciled in. Might as well do it right.
I got sick to my stomach yesterday. I may have drug my feet too much on
buying my DCC system. I would rather buy new equipment. Blue Ridge Hobbies
had the best price I could find and yesterday I discovered they have gone up
around $150 on the chief and power supply. Blue Ridge WAS about 28% off list
price. They had everybody beat. The best discount I have heard was 30% off
and that was from digitrax to model railroad clubs. Since I am not a club I thought
28% was decent. Now that is gone. Anybody have a good place to buy digitrax
systems. I am just going to buy the duplex radio system cause I know someday I
will want it.


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## NIMT (Jan 6, 2011)

Sorry, I'm of no help getting you one at a good price, I paid way too much for mine. I probably have over $3000 into my set up. It was from the good old fat and happy days of construction and remodeling overload!
Just to drive the knife a little deeper, Get a PR3 as soon as you can it will make programming and use of your system soooooo much nicer!
I have 2 PC's that run my equipment and it's a blast!
If you need to Decoder any engines you can get NCE decoders for fairly cheap if you buy in bulk, and I think they are some of the toughest out there!


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## mopac (Feb 24, 2011)

Thanks for the info. I will be doing installs. I have a boat load
of dc engines.


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