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Model Railroading > DCC track voltage for HO

Date: 05/22/11 21:45
DCC track voltage for HO
Author: RioGrandeFan

Lately I have been involved with discussions with various folks about the "proper" DCC track voltage for HO scale. The NMRA seems somewhat vague on it to me. They have a graph in one of the standards that shows it just under 15 volts. I know a couple years ago I saw a graph that had 15.1 off to the side. Can't find that one now for some reason. Some folks say it's 14.25 volts, some 15, some 15.1, some 16.

Since having seen that graph that had 15.1 next to it a couple years ago I have mine set to 15.1. A guy I recently talked to swore it was 14.25 and has his set to that.

Those of you that have HO layouts that use DCC, what do you have your track voltage set to and what is your reasoning behind why you have it set that way? What is your interpretation of the NMRA standard for the DCC voltage?

Thanks for all answers.

Rio Grande Fan
Denver, CO

Date: 05/22/11 23:06
Re: DCC track voltage for HO
Author: NDHolmes

By the time you factor in voltage drop across the layout and so on, it doesn't really matter whether it's 14 or 16. S 9.1 part C says decoders must handle a minimum of +/- 7V and an operating maximum of +/-22V, and must withstand +/-27V for HO and larger. Higher voltage will allow for higher speeds and overcome voltage drop from crappy wiring (too small or too few feeders), but creates more heat in the decoders. Personally I'd set it to a nice even 15V and call it a day. I actually doubt most command stations can regulate the voltage tighter than about 5% anyway (so the difference between 14.25 and 15 isn't actually significant).

Date: 05/23/11 11:12
Re: DCC track voltage for HO
Author: ATSF429

Using Tony's Ramp meter my Digitrax Chief measures 13.5 volts in the HO mode. Voltage drop on most layouts with today's can motors is normally very little on the average size layout. We are talking low current and low resistance resulting low voltage drops using ohms law. I use 20 gage wire and see very Little drop with 22 gage feeders. Layout measures 15 by 6 foot with the power supply near the middle of the layout. You cannot use a regular volt meter do to the waveform in DCC to get accurate readings.

Date: 05/23/11 17:53
Re: DCC track voltage for HO
Author: Chad

For what it's worth, my Digitraxx system set to HO shows 14.2 on the rails and everything runs just fine. Plus all my units are sound decoders.

Date: 05/23/11 19:33
Re: DCC track voltage for HO
Author: barrydraper

Again, for what it's worth.... NCE sets their 5 amp boosters at 14.5 volts, basically for HO. It is user adjustable with an internal pot.

What IS important is to have all boosters on a layout set to the same voltage. Otherwise undesirable current will flow between the boosters (and through the trucks of your locos) as they cross from one power district to the next booster.

Barry Draper

Edited 1 time(s). Last edit at 05/23/11 19:36 by barrydraper.

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