Power to Current Layout.

Delta969

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Please see the attached drawing. This is the only layout I have operating at the current time. It is simply circles; the two on the bottom are made with mostly 5` curves and the two on top are totally 4` curves and 12050 and so forth switches. The entire baby beast measures perhaps 15`x20`. I usually run set size LGB 0-4-0 locos, LGB 0-6-2 locos, a USA UP switcher (cow and calf) and just for fun, I recently put an ARISTOCRAFT Union Pacific FA-1 diesel on it. I used an old Marnold power supply because it has meters which monitor volts and amps used. As the FA-1 began pulling 12 pieces of rolling stock ranging from medium and full sized box cars, hoppers, and the like, once it got up to speed (I never make them go very fast), I checked the amp meter and it never got above 1 amp; perhaps 1.1 at the most. For a small layout like this, running an FA-1, is that about right? I hear people talk about lots of power needed but it doesn`t seem to be the case on this layout. Even when I put two LGB 0-6-2`s on the track and tell them to pull a dozen pieces loaded with 101 dalmatians or dinosaurs (depending on the kid`s wishes), the meter never gets above an amp, or slightly above. I even used my new VOM and it verified what Marnold already told me. I have a 10 amp power supply for my mainline and hope that will be sufficient for my 2-8-8-2 ARISTOCRAFT. That`s the largest loco I have, unless I put my ARISTOCRAFT UP ABBA on the track. That may require more power, yeah? I`ll never pull more than 15 pieces of rolling stock, but they`ll all be the big boys; 50 footers included.

The reason I ask is because I`d love to use a Marnold power supply for this 4 loop layout and a single loop with one siding nearby, which circles the brown square, so it`s close, and about 2` higher than this track, which is on trestles 15" high. Marnold is old, I love the look, the feel, and the extras it comes with, like meters, and those big handles for the kids to pull, and enough space for me to run three separate tracks on one panel if needed.  They even have panels for switches. I`ve had Marnold out for the kids to use before and they love them; especially the BIG ONE. 
 

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Things that cause drag, and hence more current, are plunger type pickups (coach lighting), some plastic wheel-sets seem to drag a lot. Weight of stock (LGB German baggage cars seem to have weight and plunger-drag), and your track layout. - Grades, or reverse curves ('S's) will all cause the current draw to go up.. Number of loco's running at any one time..
Try holding back one of your loco's to see what current it draws on stall??
That, and starting current are probably your peaks.
 
You will probably find your cow and calf use the most amps but even these two working together will take no moe than 5 amps when pulling hard with the smoke units on. USA Trains locos are known as high power users. Obviously power usage varies around the track but in very round terms I have found that typically a USAT twin bogie diesel loco will draw about 1 amp when running without lights or smoke unit. Lights vary by model but seem to add about .5 amp. The smoke unit adds another 1 amp. These are very approximate.
I have been using a 24 volt 5 amp power supply for years and regularly run a pair of USAT locos pulling over 30 wagons with no problem.
 
What current will a Marn-O-Stat handle ? That's all it comes down to, and how much it heats up. I agree there is something satisfying about using big levers and switches to play trains.
 
Amps go up with speed and worn motors. You say you run fairly steadily and we can assume your motors are in good nick - therefore a running current of about an amp is what I would expect. It sounds like a nice piece of kit and may well have been over engineered. If it works - great - just carry on and enjoy.
 
There used to be lots of engineering like that in both GPO Telephones and the BBC!
Now it is all full of 'grobbers' (small black things, with lots of legs), No one can repair it, or even work out what half of it does!! :-[ ;)
 
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