Well, according to the MTH “Mythbusters” ad in the latest MR (Digital is definitely good for something - I get mine WAY before my print copy comes) it is. This in response to the “myth” that MTH Protosound 3.0 locos run slow on DC power. Also syas the standard increased more than 10 years ago. Hmmm.
–Randy
Kind of an interesting spin on the ambiguous-as-usual NMRA standards and RP’s.
S-9.I.A says, “Full throttle voltage available at railhead shall not be less than 12 volts direct current at maximum anticipated load.”
And RP-9.I.D says, “Direct current power supplies and packs for propulsion use shall produce between 12 and 16 volts while delivering rated current.”
So while the max DC voltage can be UP TO 16 volts, a voltage that high isn’t the “standard”. It’s just allowed under the RP’s, and has been since at least May 1973.
While I certainly can’t speak for all DC power packs, my admittedly limited experience makes me think that at maximum anticipated load (and that’s important) they’re probably closer to the S-9 minumum than the RP-9 maximum.
I just visited the NMRA site. Most of the the electrical standards that I could find relate strictly to DCC. However, Electrical Standard S-9 states that for “… two rail equipment on model railroad layouts” … “full throttle voltage available at railhead shall not be less than 12 volts direct current at maximum anticipated load.” Notes elsewhere reduce this voltage to 8 volts for NN3 and Z scale. Last revision dated August 1984. In my experience this is typical MTH “We know best and for those who disagree, we make up our sources” techno-babble.
Many of the commercially available DC power packs will deliver as much as 20 VDC under no load, but the voltage declines RAPIDLY when load is added. For the mass-market commercial packs that don’t invest the $1 or less required to regulate the output, an at-load output of 14 VDC is common. Remember that any throttle that delivers more than 12 VDC at full load based on an open frame motor is non-NMRA-standard.
Move along folks. Nothing happening here. Just a lot of blah, blah, blah.
Rich
Well they also say their Proto-couplers work fine with standard Kadees. Maybe if bashing into cars at speeds that would have you blackballed if done on a real railroad is 'working fine…". Then they say but we include a set of kadees and it only takes a few minutes to change - at least that part is true.
–Randy
not sure that the unloaded voltage really matters. Does it matter that the less than full throttle setting produces a loaded voltage of 8V but is 16V when unloaded? (this allows those simple throttles with just a transformer, rectifier and rheostat).
While a regulator may produce a constant voltage for a variable load, is that really desirable for a locomotive. Isn’t it more realistic that a locomotive slow down when drawing more current going up a hill?
doesn’t the standard (below) say that that the full load (rated current) voltage can be above 12V, but no more than 16V?
Yep, and that’s pretty much it. I think MTH is playing this up because they’ve found that carving out a niche of MTH-compatible only product hurt sales more than helped.
In fact, MTH choosing to set their systems up to take advantage of the full range allowed of up to 16 volts was originally intended specifically to make MTH products incompatiable with others. Now the story has flipped 180 degrees and this “feature” is being marketed as something that demonstrates how compatible MTH equipment is. Wish they’d get their story straight.
I liked the part about where the problem is too many train set power packs from the 80s are being used. Yep, my gold Tyco packs need to be upgraded. [D)]
Of course its not the current hogging junk on board their engines, its our crappy power packs. They are trying to find a way to sell to the large DC market segment and justify why only their engines need 1/2 throttle to move.
High cost, toy like details, don’t like sound, poor DC performance. Whats not to like? [xx(]
LION supplies 10.2 volts of REGULATED DC to the rail heads. This keeps the trains of him moving between 35 and 45 mph, whcih was prototypical of NYCT when these cars were first built. Todays trains seldom go above 30 mph.
Some places (up grade) on my route, I will add a “substation” to provide 12 volts at the railheads. Fine in some sections, some places require a boost up grade but once up there the power must dropp back down to 10.2 volts.
Some down grades have a 7 ohm (5W) resistor to slow down the trains.
ROAR
Really? Are you the forum police now?
I have commented on this a number of times in the past. I don’t know how much MTH paid who at the NMRA, but before S-9 was revised in Aug of 1984, it read like this “PROPULSION VOLTAGE - Direct current at 12 volts (12v DC) shall be delivered at the power-source terminals.” and "MOTOR SPECIFICATIONS - All propulsion motors (perminate-magnet field or wound field) shall be designed for satisfactory operation at 11 volts direct current (this will allow voltage drop in the wiring, rails, etc, when 12 volt storage battery is used as power source)
That version of S9 was dated Feb 1963, and I still have the original paper copy sent to me when I joined the NMRA in 1968.
I think the meaning was clear then - satisfactory operation on 11 volts would include a reasonable scale top speed at that voltage - MTH fails that test.
Even under the current S-9, section I-A clearly says “full throttle” at “12 volts” which would seem to also imply a reasonable scale top speed at 12 volts. - again MTH fails.
The guidelines of RP-9 simply alow for the regulation percentage of the power supply transformers to be wide, allowing for the use of inexpensive power supplies without regulator circuits.
And RP-9, III-A requires reasonable scale top speeds at the reference voltage of S-9 - 12 volts - MTH fails.
Personally, as a DC operator I am offended that MTH would attempt to sell such propaganda. On my layout I use 13.8 volt filtered and regulated power supplies to power my Aristo Craft Train Engineer Radio Throttles, which then put a maximum voltage of about 13.3 volts on the rails. Almost ALL of my locos run at reasonably correct top scale speeds
Good old MTH - Everybody’s out of step but me.
Happily for all concerned, the probability of any MTH product finding its way into my layout space is just about the same as a tsunami in the dessicated desert (2200 feet above MSL, three mountain ranges in from the nearest seacoast.)
And, for the record, my DC power supplies all max out at just about 12V under normal load, but my trains run at (restricted) track speed on 8-9 VDC.
Chuck (Modeling Central Japan in September, 1964 - analog DC, MZL)
At one time for HO, 6 volts was common as the maximum voltage. Back when DC powerpacks were rare, modellers often used car batteries to power their layouts. In that context, it might make more sense that the NMRA would set a minimum and maximum voltage when powerpacks started to be made. Otherwise, some packs would be 6V, some 12V, some something else.
Yes, the pre-WWII standard for OO/HO was 6 volts, idea being that the little motors couldn’t take more than that without burning up. Yes, car batteries of the time were 6V - but O scalers used car batteries for power too, just two of them in series.
–Randy
My print copy of the March issue arrived today, and after reading the exact language of the ad, I send MR and the NMRA the following letter:
Gentlemen,
As a long time member of the NMRA (originally joined 1968), I am outraged by the way MTH has misrepresented the NMRA Standards and Recommended Practices in its latest advertisement on page 3 of the March 2014 issue of Model Railroader.
Since when is the standard voltage for DC operation 16 VDC? While current Standards and RP’s allow for voltages higher than 12 volts, it is clear that satisfactory operation at 12 volts is still the NMRA STANDARD.
It would seem to me that MTH, and Model Railroader by allowing this ad copy, have misrepresented the NMRA Standards and Recommended Practices.
It is clear that MTH has a specific agenda that has long pushed its own proprietary operating systems. This latest move is clearly an attempt to usurp the reputation of the NMRA to support and justify their design choices in manufacturing their products.
I would hope that the NMRA would take some action on this issue. It is unacceptable in my view to allow MTH to misrepresent the NMRA Standards and Recommended Practices in this way.
Personally, I am still a DC operator in HO scale, and I assure you that all the various brands of locomotives running on my layout operate at suitable scale top speeds at only 12 volts. In fact I use regulated power supplies set at 13.8 volts to power the throttles I use.
It is offensive for MTH to suggest that I should, or would even consider, changing my power supplies to accommodate their products. Quite the opposite is true. The choices MTH has made in
Sheldon,
I agree with you on this one. (dodges flying pigs) [(-D]
Paul A. Cutler III
One hunnert percent behind you Sheldon.
The NMRA needs to clarify reality before the misinformation campaign takes over.
In advertising, truth is relative. Years ago, a judge ruled Castrol could call its oil “synthetic” event though it wasn’t. Since then, there are only a few true synthetic oils out there. I’ve been messing around with model railroads on and off since 1960 and I’ve never heard of anything other than 12VDC as the standard. I’d be willing to bet that voltage standard is why the dreaded 
slot cars motors were 12v. Lots of motors available from model rr’g. Why reinvent the wheel?
On a side note, the early guys like Ellison used BIG batteries. IIRC, Ellison claimed to have batteries from a passenger rail car as a power supply. I’m not sure what type of electrical protection Frank engineered, but with the kind of current available from those cells as short could be entertaining. Mushroom cloud type of entertaining.
Lou
Well, the NMRA Std (read here, not the actual one) states “not less than 12V at the anticipated load.”
They may mean the power supply.
Meaning you have to deliver at the minimum 12VDC to the rails when loaded. Nothing says you can’t deliver 13VDC. Lead Acid batteries are 2.2V per cell, so a 12V (nominal) battery can deliver 13.2V into a high impedance voltmeter. It might deliver 12V to the track after internal and external resistances are taken into account.
Power packs can be very load dependant, so they have to be designed to deliver 12V to the rails under load. Otherwise they could deliver 12V to the terminals, but the minute you load it, the output drops to 10V.
MTH may be playing fast and loose with the truth to justify their claims. DCC voltages are higher than the nominal 12VDC as well. That is done to compensate for the decoder power consumption and for reliability
After seeing this ad…Anytime you have to go into long detail (and I love detail) to explain misconceptions about your product, you have already lost the battle. I don’t think many potential customers will be swayed by the ad. It seems right in character with other earlier ads where they dissed the competition’s locomotives…
Guy
UPDATE:
I did receive a reply from the NMRA, and they have made an inquiry to MTH about the ad and its claim.
Sheldon