I ran my locos at the club recently and noticed they went much faster than on my home layout. My home layout uses an NCE Powercab starter system, with the provided power supply rated at 13.8 volts.
However, when I used a multimeter to read the track voltage, I get 11.5 volts, which from what I'm reading online is much too low. I should be reading somewhere between 14 and 15 volts from the track.
Any ideas what could be preventing me from getting the full voltage my trains need? I have kato unitrack, and I use the provided Kato wires along with the 3 way splitters to go from the track to the circuit board that is provided with the Powercab starter system.
Any help is appreciated.
Welcome to the MR forums.
I'm not famillar with the Kato track, and wiring accessories, do you have "feeders" supplying power to various points on the lay out? or just one connection?
Typically, buss wires run from your power source, the length of the lay out, and every 4' or so, feeder wires run from the buss to the track, which is all well and good, providing the sections of track are making good contact with each other.
Mike.
My You Tube
First thing I would do is check the output coming directly from the PowerCab, bypassing the wiring and track. If it is low then it is the PowerCab, if it is within the ok range then it in the wiring or track.
First to the MR forums
Now in response to your problem I should first say I am no electricity expert, so if I mess something up others are free to correct me. I think that voltage drop may be due to some wiring problem, I think poor conductivity. Maybe a poor solder joint or dirty track? I think it would be a good idea to see if this voltage drop is found throughout the layout, and if it is different in different places.
I hope that was helpful, and I think other who know more about electricity can give some more detailed responses.
Regards, Isaac
I model my railroad and you model yours! I model my way and you model yours!
mbinsewi I'm not famillar with the Kato track, and wiring accessories, do you have "feeders" supplying power to various points on the lay out? or just one connection?
I believe the kato method of conducting power from one section to another is far more robust than traditional rail joiners.
Start at the beginning the Power Cab and measure there. Measure at the end of your splitter to make sure that cable is transmitting full power.
Measure the track to which that connector attaches and move systematically further away and find out where the electrons are disappearing
Kato track is not known to be inadequate for DCC
Henry
COB Potomac & Northern
Shenandoah Valley
It would be good to know how far from feeder wire the placed you measured was. I know voltage can drop over longer distances. Generally people put three feet and no more between feeders. Also does the electricity have to travel trough switches to get to places. This can also cause voltage drops. As previously mentioned the railjoiners shouldn’t be a problem, kato has a very good design for those.
Welcome Aboard! I have that same DCC power cab system. Mine reads around 12.3 volts. That's plenty for two-three locos running without accompanying cars. I found that generating enough power to the tracks requires feeders attached to each piece of track. When I didn't do that, the locos required more from the power cab to go a reasonable speed.
Do you know what power cab system your club uses? You might be comparing apples to oranges. There are plenty of factors at play about the volt differences. Right off, you can include wire gauges, length of feeders, and distance apart. There are multiple reason for the differences.
I don't use Kato track, so can tell you from using Micro Engineering.
I have experience with, and have held in my hands, two systems only. First was the Bachmann EZ-DCC which, if I recall, was simply a plug 'n play. I have used only the Digitrax DB-150 since then, but it needs a separate(ly purchased) power supply.
If your system just needs to be plugged in, then my observation doesn't apply. But, if you need a 'wall wart' to plug in so that your system will operate, as my Digitrax system does, then you should suspect the power supply before anything. You must verify its output.
For those of us who don't know what Kato rail joiners look like, here is a video of adding feeders. The author doesn't say why he had to do that.
Cool. I know nothing about Kato track, nice little video. So these must clip on the bottom.
These must be what holds the sections together?
I think the OP's problem has to do with his power source.
how much voltage drop is there across circuit breakers and block detectors?
greg - Philadelphia & Reading / Reading
mbinsewiI think the OP's problem has to do with his power source.
I'm wondering about the 3 way splitters. They look like mini power strips that accept the Kato plug. How many are there and how are they connected?
George your initial posts are moderated, so we may not see your answer today.
I don't think the voltage reading is too low at all. Depends on the meter being used. Seems about right to me. You aren't going to get 14-15 volts out whith a 13.8 volt input.
Your same meter may very well show 14 volts on the rails at the club, which is still a significant difference. But that's pretty much how it is. Most locos run too fast for model railroad curves and distances anyway.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Most DCC systems do a step down. A 15 volt input will usually give around 13.8-14 volt output.
I would check your input voltage from the power supply. if its a 12 volt supply, its not going to output 12 volts to the rails.
My digitrax system outputs 13.8 volts on the HO setting using a 15 volt power supply . My sprog outputs 13.8 volts with my 15 volt power supply. It outs 11 with a 12 volt power supply.
Your club layout probably uses 15 volt power supplies. The power supply that comes with a the powercab is 13.8 volts which means your track voltage will be lower than that.
Colorado Front Range Railroad: http://www.coloradofrontrangerr.com/
Yes, welcome.
I have had the Power Cab for some years. My Harbor Freight meters have measured about 13.6 vac with a loco on the rails. A scope measured about the same. Yes, P to P but did the math.
Same at the club with the five amp Power Pro.
I would measure first at the little output terminal block on the panel and then the track if he has not done that.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
I love a thread that gets me to think.
My power cab goes to a PSX circuit breaker then to a bus that has feeders to barrier strips which supply feeders to the rails.
Measuring with my HF meter at the input screws of the PSX I get 12.9 vac, the output screws 12.8 vac and the track 12.3 vac. edit (I cannot find this statement: Wiring for DCC cautions against using barrier or terminal strips. I have no club to compare, but I don't notice abnormally slow running.
Since there is so much hand wringing about voltage drop off and wire gauge of the bus, Randy's comment surprised me. (the OP doesn't know the players, but Randy is the guru and I am the guy at the end of the bar, or maybe the guy in the gutter outside the bar ) Is max speed in DCC equal to max voltage in DCC?
I don't know why the caution against barrier strips. I used them on both my last two layouts, to make the DCC shelf removable from the layout to do all the wiring witht he circuit breaker and stuff from somewhere besides under the layout, and then I could put it in place and just connect up the bus wires to the approriate terminal strip locations. I did crimp ring terminals on the bus wires (not spades - so I have to remove the screws completely - a little more finicky but also pretty much impossible for a wire to pull loose - I also solder the crimped on terminals despite having a proper crimp too for them, I am not a big fan of anything that is just crimped, anywhere).
Yes, top speed will depend on the DCC voltage. The loco always sees the full voltage, but the motor only gets part of it - pulse width modulatioon means the power is on only for a certain percentage of the pulse. 100% on, the motor basically sees the full track voltage, minus some losses in the electronics of the decoder. 50%, half speed, the power is on to the full voltage for half the length of the pulse and off for the other half. This results in the motor seeing exactly half the voltage. Or 25%, or any speed in between. The actual track voltage will affect the speed the loooco runs at ANY speed step, not just full throttle. 50% of a nominal 14 volts to the rails is 7 volts, 50% of 12 volts is 6 volts, so at half speed, one loco will see a full volt higher than the other, which is definitely enough difference to see, without resorting to actually timing the loco.
You can theoretically do pulse width modulation with any shape waveform - but with a sine wave, the calculation of the average voltage, the effective voltage a motor sees, is much more complex. With a square wave it's actually very simple - since the amplitude (height) is constant, you're only changing the width. An area of a rectangle is simple - width x height It's easy to visucalize that if you have two rectange,s both the same height but one twice as wide as the other, the smaller one is 1/2, or 50% of the area of the larger one.
the internal components of a DCC supply lose 1.2 to 2.5 volts internally ... this means if you measure at the DC supply itself, if you get 13.8 volts there, at the output of the DCC component you will get only 12.6 to 11.1 volts there ...
you also lose 1.2 volts at the decoder itself [in the bridge assembly] so there is about 11.4 to 9.9 volts that actually drive the motor ...
this is why most DC wallwarts [or similar] suppies are around 15 volt, this is to ensure that the motor itself gets around 12 volts at top speed in HO, higher in O and only about 10-12 volts on the DC supply in N
DO keep in mind, the meter type also matters. Those cheapo Harbor Freight meters you cna sometimes get for free or for $1 with coupon will read DCC track voltage MORE accurately than a $30 meter that claims to do RMS. Even a much more expensive meter that does True RMS (meaning it can accurately measure many different waveforms, not just sine waves) - you need to check the specs. Even some name brand high end ones only go up to a maximum of 1KHz, which is way too low a frequency for DCC measurement. The accuracy above the rated frequency range drops off sharply - so once again the super cheap HF meter actually wins.
Frankly, for JUST working on a model railroad, that's all you really need. If you're going to do other electroonics, or try to troubleshoot household electrical circuits, you want something better - and not always one and the same. An electrician's meter for household and industrial electricla work is designed to be safe for high voltages but may leave out ranges useful for electronics work. And an electronics type meter may leave out the higher voltage and higher current optioons of the electrician's meter. It's like any other tool - use the right one for the job at hand. That's why I have about a half dozen of the HF ones, 3 benchtop meters, and 3 fancier handhelds (I also have a problem, identified on an electronics forum I hang out on as "TEA" - Test Equipment Aquisition syndrom. But I only have a mild case of it - I only have ONE oscilloscope.)
rrinker I don't know why they caution against barrier strips.
I cannot find that statement and have modified my post above. It may have been from elsewhere or it is the Mandela Effect. In fact there are several recommendation to use barrier strips.
I spoke to NCE Corp's customer service about this issue. They told me that the ultimate test to check the voltage is not on the track but on the back of the NCE control panel. The flat control panel--where the hand-hand remote connects--has a plug with two wires that connect to the buss wires. You remove the wires from that plug, put the multimeter probes there, and turn on the system. You then compare that volt reading to what you get from the track, as done previously.
NCE also agreed with me that a multitude of variables exist that factor in to generate electrical differences. I mention just a few above in an earlier post. The concern for all is if a volt output difference is greater than one.
I hope this resolves the issue.
That is the point I was trying to mention. First point to start at.
When I saw 13.6 vac and I knew the power pack was 13.9 vdc, I knew I was good. I used the 13.6 vac as a bench mark.
Some years ago a few told me my meter was not accurate then. Go figure.
Locos ran good at home and the same at the club.