On many forums ("fori" ? ) I have read that some locomotives had a motor with a nominal (maximum) voltage about 9~10v, and some others 12v. Would it be possible to indicate this information on the site ? This could be helpful, if one (me too ... ) didn't yet decide between two models of locos. And I think that 10v models could be powered with 12v without any damage by using a PWM with a maximum ratio of 10/12, or am I wrong ? Not everyone is running DCC !
Thanks for every answer ...
Last Edit: Mar 6, 2017 16:58:55 GMT -5 by alberich
Alberich, This is not really a simple question and the answer does include DCC. The Märklin "standard" is 10VDC maximum. Nearly all Z scale locomotives are rated for this.
One exception is MTL. They rate their F7 at 8VDC and the others (GP & SD) at 9VDC maximum, with "no pulse power." Their engineer suggested at a convention a few years back that it is safe to run the locomotives 1V higher than documented and many people are successfully running these units on DCC (pulse power) and 12V.
The other exception is AZL. Basically the locomotives that accept the DCC drop-in decoders are 12VDC rated. There is a post here by Rob(A) that lists the specific models, but as usual when I want it, I can't find it.
Thank You ! It's because I read in a topic that somebody found that a loco (I believe it was a SD) was running to slowly, and the answer was that it had a 12v motor ... I think I will use a 9v switch supply (selectable voltage output, but I will "lock" it to 9v), in a shape like those used for laptops, sold "ready to use" with regulation and filtering, and I think it will be able to power my turnouts too (I found one Rokuhan new on the Bay and it will be delivered this week, for testing purposes ... )
Post by boxcarwilly on Mar 6, 2017 11:55:52 GMT -5
As a railroader who has experimented with different engines, power packs and voltage I just want to say that it's been my unfortunate experience to learn that no two engines run exactly alike. Even engines that are supposedly paired speed wise as in the case of AZL's F series A and B units. One always runs faster then the other. I have 3 GP38's and one runs so slow at 10v that the other two can lap it twice on a 4 ft. oval track. Likewise, I have 6 MTL SD40's and none of them run at the same speed at 10v. The same for my SD75's and so on. It's a sad fact, but none the less true, you can get 5 brand new engines from the same manufacturer and even though they are manufactured to the same tolerances and specifications, none of them will run at the same speed. You can bet there will be variations from minor to major. It matters little how long you break them in, how often you clean them or the track or what power pack you use, the result the same. Unless you are using DCC, which I'm told is a good tool for equalizing engine speed in consists, you will never fine two engines that run exactly the same speed at any voltage. It's just the nature of the beast. You can come close, but that's as far as it goes. I put all my engines on the track, crank up the power to 10V and see which one's of a certain type run fastest. Then I number them from fastest to slowest and make note of it in my book. I do the same for mixing engine types in consists. The slower one's will act like a brake for the faster ones (if they aren't too slow) and this will allow a reasonable speed for your consist at a specific voltage. It's the hard way to do things when running DC, but if you're trying to accomplish something, sometimes the hard way is the only way. I've had fairly decent success with this process. For whatever it's worth.
I don't think I will ever use double traction. For a moment it had been an idea, when I thought about 2 RDC's coupled together ; but I gave up the project of a vintage layout ... I thought about the possibility with two modern GP locos too, only for a short while ! It would be silly, with a freight train of only 4 to 5 cars. So every locomotive will be given its own PWM signal ; I am planning a set of adjustable resistors, read by the ADC of the processor, and it would then adapt minimum and maximum speed (I know it can't be kept constant, because the engines are warming up ; but it's better than nothing). And if I come back to the "3D" layout with Rokuhan, all the way I can only run 2 trains simultaneously because of the "topology" of the layout (two stations linked by a single track on each side) ; two PWM generators with ATTiny's, and the PWM signal switched by the main controller to the amplifiers for the sections the train will run ; as I wrote in another topic, this was done 40 years ago in France by a modeller whose name was "Chenevez" by switching directly the transformer's outputs via relays according to block sections, and he described it in 3 books ; it was called "source transfer" or "source following". I only want to adapt it to more modern systems ...
Last Edit: Mar 6, 2017 17:18:42 GMT -5 by alberich
Post by Rob Albritton on Mar 6, 2017 14:43:51 GMT -5
All of our newer locomotives are rated for 12 volts. These can be identified by AZL part number. Anything with a FIVE digit part number (before the dash) should be 12 volt rated. For example AZL12345-0.
Some of our very early locomotives (brass) were rated for 9 volts. These can be identified because the AZL part numbers have FOUR digits before the dash. For example AZL1234-0.
My personal suggestion is to use up to 10 volts. Why? Well, the last 2 volts going to a 12 volt motor mainly generates heat, and not speed. Yes they run a tiny bit faster at 12 volts compared to 10 volts, but not too much. And 10 volts makes everything compatible with Marklin and MicroTrains. (It's also very close to our 9 volt maximum for older brass locos, so if you make a slip on the throttle, you probably won't do any damage)
One of my throttles is a Snail: 9V battery, PWM. I've been quite happy with it's performance for a single locomotive, 4-6 car train, so I think you'll be satisfied with your proposed solution.
I've built several throttles, the most recent Arduino (ATmega) based. I have a couple of thoughts for you from my experience. Keep the track power low, under 1A. The AZL locomotives are low current and typically with 4-6 cars run under 100mA. Design good short circuit protection. Unfortunately metal locomotive parts in Z scale can melt rather quickly in a derailment. Consider designing input voltage flexibility for the track power. My latest design will accept 9 to 12V with the controller monitoring the voltage of the wall wart I plug in. Should you decide to run longer, heavier trains in the future the extra voltage will help.
Longer trains will never be possible because of the length of the platforms and "freight tracks", for example to the gravel plant or a ... beer depot. About the protection : I found some "fast" fuses, ranging from 100 to 250mA ; I will begin with 100mA, increasing if it is to "weak". Or do You think it is not fast enough ? All the way I hope derailments will not happen too often. To rvn2001 : I don't think that using a coupler with 4 AA batteries for testing will cancel the guarantee ... or a stabilized "lab" power supply, set to 8v (with built in voltmeter) ! To markm : with Your DIY (Arduino) controller, which frequency do You use for PWM ? I have read about this subject, from 2KHz (audible) to 20KHz (inaudible). The problem with increasing frequency is the significance of self-induction.
Last Edit: Mar 7, 2017 15:17:50 GMT -5 by alberich
Even though this is not about "nominal voltage" per se, I pose this question:
I have an Aristo Craft "Train Engineer" Remote Control unit: it connects between your power source (with the power turned up as high as "max") and the track. A hand-held then controls the train. I have used this with several different types of power packs, from older MRC "ControlMaster V" to Troller "Autopulse" units, and it works fine...really well, actually.
I find this unit works very well in N, HO and O (DC) scales. One of the features I like is that as soon as you begin to "power up", the highlight come on to full brightness. I guess this is because the voltage to the track is constant(?) The range of speed control is also very good.
I'd like to try this with my Z scale stuff; was planning on using my Rokuhan RC 02 as the power source. Can anyone here think of a reason why this may not be safe to use? I could just go ahead and try it, but am fearful I might burn up a loco in the process...
Mark in Oregon
UPDATE: Because I'm impatient, I went ahead and tried this. It did not work. The only reason I can figure is that the wires from the Rokuhan unit are very, very thin, whereas the ones built-into the Aristo Craft item are full size gauge, like a lamp cord. The Rokuhan couldn't supply enough "juice" to power the Aristo unit...(?) Oh well, at least I didn't blow up a loco testing it.
Last Edit: Mar 8, 2017 20:27:33 GMT -5 by strummer
alberich, you cannot use a common fuse, you will blow it very easy. Even a 'T' (timed, slow) one. Nothing is going to blow up or instantly melt (just watch your trains, when running, in case they *derail* in a turnout or elsewhere that would cause a short). In seconds, it is possible but not a reality. Most all supplies have their own current protection so you should be OK. There are 10,000+ people running with 1 Amp or more.
There are some 250mA, 500mA and variations of thermal circuit breakers. Ohmite, Cirkit, other commercial suppliers. But super easy to build an electronic one. Again, most supplies will self limit, so you really don't need to do anything.
As for frequency of the PWM, the coreless motors don't make any noise. The Snail and some other designs are 50, 60, 120, 250 Hz range. DCC uses ~16000 Hz
You can use one of the $5-$8 LED dimmers too. Its just a PWM controller for 12/24 volts. Use a 1A 12V switching style (the modern small and very light models) available for $1
To Strummer : One thing I thought about, as far as I could understand : I believe that the Rokuhan power supply itself is a PWM device, the ratio of PWM varies with the speed control. Now if You put a second PWM control to its output and if some PWM remains, i.e. the Rokuhan's output is not pure DC, it will not work properly, especially if the second unit uses another PWM frequency : there will be interferences ; or the second unit needs perhaps pure DC for its control electronics. If You own a scope (the "ultimate tool" in electronics) or at least a handheld meter with a frequency measuring function, connect it to the output of Your Rokuhan, and then to the output of Your other controller (powered with pure DC, for example a battery), perhaps You will see some frequencies, and perhaps different ... It's only an idea, which COULD work. To BAZman : I found some schematics for a current limiter, but an interesting component too called a "polyfuse" or "polyswitch", for 250mA, 450mA, etc : perhaps is this what You meant ? But the word I read too often on this forum is "derailment" ; is Z-scale really so unreliable ? I think if the track is laid in a "clean" way (i.e. fixed to a "flat" plywood surface, with no level changes by different types of tracks), if no obstacle is on it, and if there is no problem with wheels, it should not happen too often, especially with diesel locos (perhaps steam locos could have some problems with their front wheels on turnouts, I read in another topic the problem with adding additional weight). A problem could be some turnouts in the "opposite" direction, which could not be in the correct position and cause a short circuit all the way ; but this should not happen with computer (microprocessor) control ; as You know, computers are perfect, nothing can go wrong ... go wrong ... go wrong ...
You're probably right; I should have started a new thread. I just figured since this one was about "voltage", it would be a logical place to "piggy back" my question onto.
And I think you're also correct about about the lack of current coming from the Rokuhan unit; this Aristo device has always worked very well, when supplying it with 12-16V.
Although I get what you're saying, as I mentioned I have used the Aristo unit with a Troller "Autopulse" which, as the name implies, delivers PWM as a matter of its design, so I don't believe that using a pulse-type power source poses any problems. At least I have not experienced any thus far.