Power/wiring question

[warlock_1492]

Hello all,

I am quite new to modeling....I am working on my first HO scale layout. It is on a 4X12 sheet, with one full loop around the outside, one long siding, and a 3/4 loop on the inside. My layout is powered by a 16v power supply.

My problem is this.....

When I run on the outside loop and siding everything is fine...full speed for my loco....but when I attach the center 3/4 loop to the rest of the layout my loco runs very slow, and when I unattach the inside 3/4 loop it runs normal again.

I'm not sure what exactly is the problem.....if anyone has any suggestions I would appreciate them.

Thank you

 

[Selector]

The electrons that provide the voltage to your layout only have to run around the outer loop at first, so your voltage stays relatively high all around the loop. When you add the extra trackage, you have effectively added something like 60% more length for the voltage to "fill". Think of it this way...suppose you had a somewhat rubbery thin tube filled with water. The amount of water keeps the tube swelled somewhat, and nice and hard when you feel it. That is like getting the intended voltage all along that tube.

Now, you magically add another 18" to the tube, but you add no more water. What will happen? Won't the pressurized water expand and fill the new volume? And when it does that, will the hose section that was swelled and firm stay that way? Of course not. And that, as an analogy, is what happens when you feed a fixed voltage at one point of a track system and keep adding tracks.

You would do better to run a heavier gauge wire as a bus around most of your loop, but below the bench. Something like 14-16 gauge. Soldered every 3-6' along this bus wire, through cuts in the insulation, you attach 20 gauge feeder wires that rise up and are soldered to the joiners above them. Some feeders, perhaps as few as one, would also feed the inner curved section, and there is no reason not to use the very same bus.

This is not a shorting problem...otherwise you would get an indication and the engines would stop, not slow down. So, unless I am missing something, this is voltage drop due to trying to power too long a length of rail. The bus will alleviate your problems will well situated feeders to the rails.

It is the method that the vast majority of us resort to when we anticipate or encounter voltage reductions along our track system....soldered feeders.

 

[Gardenfan]

You need more power feeders, it's just that simple. Most hobby shops recommended that I drop feeders every 3 feet. This is way overkill IMO, but you do need more than just one set for sure. If you have a standard table top loop, feeders at the front, and at the back will do a lot for maintaining track power on a given loop.

Keep in mind that if you have a bunch of locomotives in a given area, then you will experience a lot of voltage drop. Each loco is capable of dropping the voltage by .2-.5 volt which will slow things down a bit.

The above mentioned bus wire would serve you well, although for your size layout 14 gauge would be a bit overkill to be honest. You would do just fine with 16 or 18, 18 being very easy to find at most every hardware store as it is most commonly used for thermostats and central vacuum lines. Just go in a complete loop with both ends terminating at your power supply.