Track / Motor Voltage

[ELECTRON]

Hi all from a new member and relatively new to DCC.

I note that DCC seems to be primarily directed towards OO Gauge runners to control loco's fitted with 12v motors.

I however run O Gauge and my loco's are all fitted with 24v motors.

I currently use a Digitrax Zephyr controller + a MERG Cancab, Command Station and Boosters all running from a 24v supply.

I am finding however that regardless of which controller I use I can't get much more than 15v across the motor terminals

with the speed CV's at max.

Can anyone answer if this is determined by the decoders, the controller / boosters or both and or is there a DCC system that can

drive loco's at 24v. 

[Ron Ron Ron]

The Zephyr and other manufacturers' "starter systems" are generally designed for use with H0/00 (or S) and smaller scales.

 

For example, the Zephyr manual states 13V track output voltage and the product description on the Digitrax website, says that it is suitable for use with N and H0 models.

 

For the larger scales, it would be better to use a "full fat", higher powered system, most of which have selectable track voltage outputs to cater for the larger scales.

 

One option would be to add a separate Booster (with a selectable output) to the Zephyr and use that to power the track.

A Digitrax Booster, connected via LocoNet would be a suitable choice.

 

I hope that helps.

 

 

.

[Nearholmer]

A question that I'd pose is: bearing in mind that speed is proportional to applied voltage, how fast do you really want your trains to go?

 

I run a variety of nominally 12V and nominally 24V  0 gauge locos on my layout and don't think I've ever run at more than c12V, because even the 24V locos will exceed reasonable operating speeds at more than that, and the 12V locos rarely need more than 8V to yield a sensible speed.

 

If you are using commercial models, rather than home-builds with super-low gearing, 15V on a nominal 24V loco is likely to give an "express" speed, and the full 24V is going to take you into TGV territory.

 

Kevin

[John K]

Hi Electron

Can I ask about your initial premise.

The modern O gauge world no longer uses heavy open frame motors, and does not run at 24V. Little maxon or canon motors driving high efficiency gearboxes are the order of the day.

Are you running very old models?

Except for a few, heavy drawing, twin motored diesels most O gauge DCC-ers, of which there are now very many, use standard OO/HO rated decoders.

I have been running DCC in O gauge since the turn of the millennium.

John K

 

Edited July 27, 2019 by John K
Correction

[Nearholmer]

Modern “coarse” 0 production still uses 24V motors in some cases, although “can” rather than open-frame, which is where my experience of 24V comes from.

 

Oddly, much of my experience of 12V in 0 comes from “heavy open-frame” motors in 1930/50s Bassett-Lowke, which, if kept clean and sparingly lubricated, are remarkably good pieces of machinery, having long-lived magnets, with current demand only c750mA under light load.

 

Which is to say that the “modern 0 gauge world” is not monolithic.

[Hamburger]

17 hours ago, ELECTRON said:

Can anyone answer if this is determined by

1.) the decoders,

2.) the controller / boosters or both

3.) and or is there a DCC system that can

drive loco's at 24v. 

Hi,

1.) usually DCC decoders supply track voltage minus 1.4 volts to the motor as a peak voltage.

Maximum RMS voltage is a bit lower due to cutouts for back-EMF measuring and, if active, Railcom cutout.

Could be up to approx. -20% depending on motor parameter settings and Railcom on.

 

Please note that the motor always gets pulses with full voltage so its torque is always high.

Speed is determined by length and/or frequency of this pulses.

 

2.) Track voltage is determined by booster settings (or controller settings if the controllers internal booster is being used).

Provided that the power supply for the booster is sufficient, too.

 

3.) I know that both Massoth and Zimo can supply 24 V track voltage. Others most often are limited to 22 volts which should still be sufficient for the 0 gauge.