I’m powering my rails with a non-train transformer with multiple taps. I use the 24 volt tap. Speed is controlled by routing this output through a large reostat which I guess controls the current? These are items my dad had salvaged somewhere and I found with the train stuff. Sidings are de-powered via a panel of on/off toggle switches. A seperate, small Lionel transformer powers the switches, but was inadequate for track power.
Could this setup in anyway be harmful to my engines (Lionel pre and postwar and some MPC)?
runtime
24 volts is a bit high for postwar and MPC trains. Could be okay for some prewar trains. With the reostat at minimum resistance, the full voltage is presented to the trains.
You say it is a multi-tap transformer? Use a meter and find a tap that is 18 to 20 volts to be safer. If not already there, I would add an 8 to 10 ampere circuit breaker as well. With non-train transformers a derailment can put a lot of current through wheels and axles. And the reostat.
John Kerklo
www.Three-Rail.com
Thank you John.
There is a 20 V. tap; but my recollection from a few years ago is that it was not ssufficient to power my engines around my 12 x 15 outer loop (possibly due to some poor conductivity in old lionel track). The reostat is really big - bigger than my fist in diameter.
Where would I pick up that type of circuit breaker?
runtime
You can get auto-resetting circuit breakers with various current ratings at many automobile parts stores. These are very similar in principle to the ones traditionally used in toy-train transformers.
You may be advised to use fuses or some sort of very fast electronic circuit breaker, to protect modern electronics-intensive locomotives (if you have any). A much better and cheaper protection is a transient voltage suppressor (TVS) connected across the track. Let the circuit breaker protect the transformer and wiring, which is done best by a conventional breaker without any nuisance tripping.
It’s recommended that you run a “hot” lead to the middle rail of the track every three track sections. Just solder it right to the rail. If you’re not doing that, then you ARE suffering voltage loss in the system the further you are from the source.
Jon [8D]
Its good to find a local electronics supplier but these are getting hard to find. Try these internet suppliers. I have used them all. Buy something and you will get a useful catalog forever. These suppliers are also good for wiring aides like barrier strips and wire terminals.
http://www.allelectronics.com/
http://www.jameco.com/
http://www.mouser.com/
Some more comments on using a reostat to control trains.
Placing a resistor (the reostat) in series can limit the current to a train but there can be some difficulties. The voltage dropped is proportional to the current through the reostat. The higher the current, the higher the voltage drop. A problem can arise when the train is placed in “neutral.” The train is drawing little current, so a higher voltage is delivered to the track. A light bulb in a train car will then receive a higher voltage, perhaps high enough to burn it out. Thats why I recommended using a 20 volt tap.
If you see a large voltage drop, there may be more going on. Is there a fixed power resistor also in the train circuit?
If you are serious about running the trains I would recommend picking up a train transformer. A low cost postwar train transformer won’t set you back much and will be better for the trains. Use the multitap transformer for lights and accessories.
John Kerklo
www.Three-Rail.com
A good place to buy circuit breakers is Scott’s Odds and Ends. www.scottsoddsnends.com Available in 10, 15 and 20 amp sizes, I would recommend theses over automotive style breakers. At least look at Scott’s Odds and Ends before buying elsewhere, prices may be a lot better.
Lee F.
Thank you all for your feedback. I’ve been running with this setup for quite some time now, but only maybe 20min per day. My conclusion so far is that I’m not harming my engines??
I needed to use the 24V tap because I was losing too much power at the far end of the layout (12 x15). I thought I’d try another lockon at the low power far corner instead of the soldering, since I anticipate making some layout changes.
I picked up a postwar ZW some months ago but haven’t gotten around to replacing the power cord, which is shot.
I practiced, by replacing the cord on a v.small 027 set transformer and found that the extension cord I used was too thickly insulated to easily fit in place of the original. it works but I had to leave off one of the cover screws which interfered with the cord inside. So I’m thinking of using lamp cord??
If a reostat (variable resistor) is not the best way to control current to the track, how is it done in train transformers such as the postwar Lionel??
Finally, is running two engines, eg- MPC GP9s roughly the equivalent of running one twin motored F3, as far as current and voltage? Does running too many motors eventually risk overtaxing the transformer or the motors? Does a circuit breaker trip when there is too much current drawn? How much current is too much? I’m currently pulling 16 cars with a 646 Hudson, and after a half dozen laps there is a strong ‘electrical’ smell in the air??
Looking forwar to all feedback,
runtime
As you might suppose, the requirements for line cords and extension cords have gotten tougher over time. Your small transformer, for example, may have been built with an AWG18 cord; but you will have a hard time finding an extension cord to replace it smaller than AWG16. I would expect the ZW however to have started out with something larger.
For prewar trains, rheostats were used, both with transformers and with batteries. The postwar technology has a transformer with the surface of the secondary winding exposed. A wiper attached to the handle moves across the turns of that winding to vary the number of secondary turns in the circuit and therefore the voltage. The wiper is just a piece of metal for smaller transformers, or a carbon roller for larger ones like the ZW.
Yes, two single-motored locomotives are roughly equivalent to a single dual-motored locomotive, pulling the same train.
As long as the transformer is protected with the appropriate circuit breaker, which is 15 amperes for the ZW, you can safely run as many motors as the circuit breaker will allow. It does trip when you exceed its rating, but not immediately. The greater the overload, the sooner it trips. This is a reasonable way of doing it, since the transformer and wiring are not damaged immediately, but themselves must heat up before any harm is done. This prevents what is called “nuisance” tripping from brief overloads or short circuits.
The smell is likely ozone, produced by the arcing at the motor brushes.
An additional lockon is a good temporary way to determine a power distribution problem. Use an adequate wire size, like #14 or, at least, #18 gauge wire. You might also use track pliers to tighten rail joins.
Another thought. How long has it been since the engines were serviced? If not recently, then this is likely part of your problem. Old grease can cake up and seriously slow down the trains. Clean out all the old grease from gears and replace with white grease. Clean the armature plate with alcohol and 300 grit paper. Use something like 3-in-one oil for bearings. Don’t use any automotive lubricants. Clean the wheels. Especially use a small screwdriver blade to scrape off the buildup of crud and then clean the wheels with alcohol and a q-tip. Clean all the rolling stock wheels too.
John Kerklo
www.Three-Rail.com
Thank you both again for your helpful replies.
John, I follow the cleaning procedures you indicate for wheels and gears, using lubricants from my LHS. I’m not familiar with the armature plate. Could you describe where it is, what it looks like, and what must I dissassemble from the motor, for both steam and diesel? Or point me to the right drawings at Olsens?
Bob, I am controlling the transformer output with a device such as you describe. Mine happens to be free standing, looks like 5" in dia.cylinder, has a center mounted shaft with an arm that rotates across the coils which are wrapped vertically about the cylinder. So maybe I only need to add a circuit breaker, whose purpose I gather is primarily to protect the transformer? Would 15A be about right? And again, what kind of breaker, and where, other than the previously mentioned web site would I get one. We have several industrial electrical and electronic supply houses in my area.
I’ll try to post some pics shortly.
runtime
You can get auto-resetting circuit breakers with various current ratings at many automobile parts stores. These are very similar in principle to the ones traditionally used in toy-train transformers.
The rheostat does have exposed windings and a wiper; but it’s not the same as a variable transformer. It is just an adjustable resistor and is wound with high-resistance wire, not copper as a transformer would be. Nor does it have an iron magnetic circuit nor a primary winding. Yours sounds like its pretty big, which is good. If you can find ratings for it, there are two numbers that will characterize it, the power rating and the total resistance. The number you really need is how much current it will carry safely, which you can compute by dividing the power rating by the resistance, then taking the square-root. If the numbers you need are not stamped on it somewhere, but you have any sort of manufacturer’s part number, I would be happy to take a stab at finding the ratings for you.
You also need to know the transformer’s ratings. See if you can find any numbers on it also.
Finally, consider the wire that you are using. You should consider that AWG10 can carry 30 amperes, AWG12 20 amperes, AWG14 15 amperes, AWG16 7 amperes, AWG18 5 amperes.
Then put all three current ratings together by choosing the lowest of the three numbers, rheostat, transformer, and wire. That is the highest current rating that you should use for the circuit breaker or fuse.
The armature plate is on one end of the armature and is used to conduct electricity to the armature coils. The armature is the part of the motor that turns and supplies power. Locate the motor. You will find wires going to the end of it. The wires will connect to two metal tube-like things that hold the brushes. The brushes contact the armature plate.
Usually, two screws hold on the plastic end of the motor. Remove them and lift off the end of the motor. The armature plate is exposed. The brushes and (sometimes) brush springs will fall out. Clean the armature plate. The brushes are cylinders of carbon. If less than 1/4 inch long, replace. If more than 3/8 inch, they are okay. Reassemble, making sure to get the springs and brushes back as they were.
Cleaning the armature will help, but won’t cause a dramatic difference unless it was really bad.
I wonder if you have an autotransformer, rather than a reostat. Is the “reostat” really heavy with the exposed coil of wire copper colored and wrapped around a stack of metal laminations?
John Kerklo
ww.Three-Rail.com
That’s an interesting throught, John. Here is a rheostat, with white-colored wire (probably nichrome) wrapped around ceramic:
and here is a variable autotransformer, often called by one of the brand names “Variac” or “Powerstat”, with copper wire wrapped around iron:
What John calls an “armature plate” is what I know as a commutator.
