Optimal Volt and Amp for N and H0 scale ??

[domino]

Hey all

 

I was just wondering what is the optimal volt and amp for running N and H0 scale ??

I have a old Lima transformer with 12,5 volt and 0,25 amp output , and a old Trix transformer with 13,75 volt and 0,5 amp output, my N scale trains runs much better with the Trix Transformer , so clearly 0,5 amp is better, but what is the optimal output for N and H0 scale ??

 

Thanks

 

Brian

[cteno4]

Brian

 

Usually around 12v is the max for most n scale trains. You are correct 0.25a is a bit low for a power pack. .5a or more is better, especially if you have 2 motor cars. Kato power packs are about an amp.

 

Jeff

Edited July 1, 2013 by cteno4

[Martijn Meerts]

N is generally designed for 12 volts, but all the digital systems (including Selectrix, which is designed for N) output more. Some digital systems have variable output, like the ECoS and the Lenz system, but the lowest they go is usually around 14.

 

H0 is usually around 14-ish, Marklin may be a bit higher than that. Digital systems generally output around 16v on the H0 setting.

 

Amps doesn't matter that much, just make sure to have enough to run trains :) My 6 car 800 series with internal lighting uses around 0.125 amps when running, which is lower than it should be considering the interior light is supposed to be about 20 milli amps, guess in reality it's closer to 15 per car.

 

 

[domino]

Thanks both

 

Brian

[KenS]

As mentioned N scale is nominally 12V and likewise HO scale is nominally 16V (there are charts in the back of NMRA standard S-9.1 that say 14.5V, PDF, and some people will say 14 or 18) but reality varies a lot. What standards there are, are only erratically applied.

 

Most power packs for N that I've seen put our closer to 14V, although some Japanese packs designed for smaller trains put out even less than 12.  A train will run fine on 12, but slower than on 14 (for most models 12V still makes them run much faster than the prototype). While HO is nominally 14.5V, many packs put out 16-18 volts in my experience, and some as much as 22. Unless you have small kids (or are a kid at heart) and are going to turn the pack up to full for supersonic train operation, too-much voltage isn't going to cause a problem, because at any reasonable speed no matter what the maximum rating, the pack will be putting out less than 12 volts.

 

The real issue with lower voltage is track loss.  You can lose a couple of volts between pack and rail with sectional track, particularly if it's long.  A 12V pack then may only be getting 10V to the train, and that will begin to become obvious.

 

Aside from small models (trams) any N-scale train sold internationally is going to be designed for 15-16V, because a lot of power packs designed for HO/N will use the HO voltage. Kato models seem to be just fine with such power, and I haven't heard of problems with Tomix trains, but I think I recall hearing that some tram models are more sensitive.

 

As sold in the U.S., Kato packs put out about 14.8V (that may be a "peak" number, as the voltage isn't flat DC but has some "ripple" to it). A pair of MRC HO packs I own put out just over 19V under load (running a small N-scale loco with no cars). My Kato packs are rated for 1.5A (1,500mA) input power, but that doesn't mean they can output that much.

 

On Japan-spec 100V power, my Tomix N-400 (Japanese) pack puts out 10.4V, and my Tomix N-1 puts out 10.2V while running a tram, and closer to 11V unloaded. These are rated for 400mA and 500mA of output power respectively.

 

The "stall current" rating of a motor is the maximum it can draw, but except under exceptional circumstances a motor won't draw that much, and it's not a problem if the stall current is higher than the power pack's maximum output.

 

DCC Decoders, on the other hand, need to be sized for stall current, because if the train gets stuck against an obstacle on the track it could draw full current for an extended period and burn out a too-small decoder, but when it comes to sizing power supplies for multiple trains, real-world use per train on average is going to be much lower.  For example, a Kato DE10 with a stall current of 160mA never drew more than 70mA when I tested it running.

 

Adding a load (pulling cars, going uphill) will raise that, but in my measurements not by very much.  I measured power for several of my models two years ago and reported that in another thread here, and saw a worst-case of 135mA without lighting. 

 

The current required depends not only on the train and what it's doing, but on accessories like lights and sound, and sound will add a lot.  For lights, I expect a typical "small LED" adds less than 20mA per car (I've seen numbers close to 10mA), larger LEDs could be 30-50mA, and bulb lighting could be 60mA per car. Some sound-decoders are reported to use more than an Amp, although I've never looked into that closely, and that may only be peak draw at startup when charging their capacitors.

 

Older motors will draw more power, and locos with dirty drive trains will have more friction and draw more power.  I don't have numbers for that.

 

For sizing DCC power supplies, for the modern N-scale EMUs I operate, without sound, I'm using 250 mA/train for planning purposes these days, but I'd probably want twice that or more if I did sound (I really ought to find out what the typical draw of a sound decoder under load is).

 

A couple of typical HO packs I own can, in theory, put out 750 mA of power at full voltage although I haven't measured them to see what they actually can do (I don't have any trains that use that much power).

 

I've run N-scale trains on a 600mA 12V Arduino output, as well as with my Tomix pack that only puts out 400mA @ 10V. Both ran fine at prototypical speeds (which might be too slow for some).

 

For N-scale, I'd look for a pack that outputs 12-14V (one with a specific "N-Scale" description or a switch) and at least 500 mA, although less would probably work fine.  For HO I'd look for 15-18V and "1 Amp", but as noted I have two HO packs that don't put out an Amp and one of them ran multiple loco HO trains just fine back when I had those. Realistically 750mA seems to be the norm here.

 

I have some pages on my site detailing my research into train and power-pack requirements from a couple of years ago.

 

[domino]

As mentioned N scale is nominally 12V and likewise HO scale is nominally 16V (there are charts in the back of NMRA standard S-9.1 that say 14.5V, PDF, and some people will say 14 or 18) but reality varies a lot. What standards there are, are only erratically applied.

 

Most power packs for N that I've seen put our closer to 14V, although some Japanese packs designed for smaller trains put out even less than 12.  A train will run fine on 12, but slower than on 14 (for most models 12V still makes them run much faster than the prototype). While HO is nominally 14.5V, many packs put out 16-18 volts in my experience, and some as much as 22. Unless you have small kids (or are a kid at heart) and are going to turn the pack up to full for supersonic train operation, too-much voltage isn't going to cause a problem, because at any reasonable speed no matter what the maximum rating, the pack will be putting out less than 12 volts.

 

The real issue with lower voltage is track loss.  You can lose a couple of volts between pack and rail with sectional track, particularly if it's long.  A 12V pack then may only be getting 10V to the train, and that will begin to become obvious.

 

Aside from small models (trams) any N-scale train sold internationally is going to be designed for 15-16V, because a lot of power packs designed for HO/N will use the HO voltage. Kato models seem to be just fine with such power, and I haven't heard of problems with Tomix trains, but I think I recall hearing that some tram models are more sensitive.

 

As sold in the U.S., Kato packs put out about 14.8V (that may be a "peak" number, as the voltage isn't flat DC but has some "ripple" to it). A pair of MRC HO packs I own put out just over 19V under load (running a small N-scale loco with no cars). My Kato packs are rated for 1.5A (1,500mA) input power, but that doesn't mean they can output that much.

 

On Japan-spec 100V power, my Tomix N-400 (Japanese) pack puts out 10.4V, and my Tomix N-1 puts out 10.2V while running a tram, and closer to 11V unloaded. These are rated for 400mA and 500mA of output power respectively.

 

The "stall current" rating of a motor is the maximum it can draw, but except under exceptional circumstances a motor won't draw that much, and it's not a problem if the stall current is higher than the power pack's maximum output.

 

DCC Decoders, on the other hand, need to be sized for stall current, because if the train gets stuck against an obstacle on the track it could draw full current for an extended period and burn out a too-small decoder, but when it comes to sizing power supplies for multiple trains, real-world use per train on average is going to be much lower.  For example, a Kato DE10 with a stall current of 160mA never drew more than 70mA when I tested it running.

 

Adding a load (pulling cars, going uphill) will raise that, but in my measurements not by very much.  I measured power for several of my models two years ago and reported that in another thread here, and saw a worst-case of 135mA without lighting. 

 

The current required depends not only on the train and what it's doing, but on accessories like lights and sound, and sound will add a lot.  For lights, I expect a typical "small LED" adds less than 20mA per car (I've seen numbers close to 10mA), larger LEDs could be 30-50mA, and bulb lighting could be 60mA per car. Some sound-decoders are reported to use more than an Amp, although I've never looked into that closely, and that may only be peak draw at startup when charging their capacitors.

 

Older motors will draw more power, and locos with dirty drive trains will have more friction and draw more power.  I don't have numbers for that.

 

For sizing DCC power supplies, for the modern N-scale EMUs I operate, without sound, I'm using 250 mA/train for planning purposes these days, but I'd probably want twice that or more if I did sound (I really ought to find out what the typical draw of a sound decoder under load is).

 

A couple of typical HO packs I own can, in theory, put out 750 mA of power at full voltage although I haven't measured them to see what they actually can do (I don't have any trains that use that much power).

 

I've run N-scale trains on a 600mA 12V Arduino output, as well as with my Tomix pack that only puts out 400mA @ 10V. Both ran fine at prototypical speeds (which might be too slow for some).

 

For N-scale, I'd look for a pack that outputs 12-14V (one with a specific "N-Scale" description or a switch) and at least 500 mA, although less would probably work fine.  For HO I'd look for 15-18V and "1 Amp", but as noted I have two HO packs that don't put out an Amp and one of them ran multiple loco HO trains just fine back when I had those. Realistically 750mA seems to be the norm here.

 

I have some pages on my site detailing my research into train and power-pack requirements from a couple of years ago.

Thanks Ken

 

Brian