Large Scale Central

saving on wires possible?

Electronics Power and Sound
#1

for some time now i am doing the worst part of having an analogue DC layout - wireing!

to evade, that under the layout it looks like a spagetti factory, and to save some money, i am thinking about common wires, wherever possible.

in the first drawing is shown, how i common-wire my blocks.

now i got an idea. but i’m not sure, if it would work. for my 16 turnout switches and their reed contacts i need many wires.
it would save a lot, if i could hook their common wire onto the common wire of the trackpower too.
(as in pic two)

with my very limited knowledge about electricity i don’t see, why not. am i wrong?

#2

Yes Korm, that is exactly how I do it. Except, to save even more wire, “tap” the ground for the turnout right there on the rail at/beyond the turnout.

My only caveat would be that the a/c source must be independent of the two d/c sources. That is you can’t use the a/c tap in one of your d/c supplies, assuming it has one.

#3

thank you!

yes, i got an extra pack for AC. (60VA, 4 Amp) that i will use at 16 V.

feederwires are easier for me. i am not very good at soldering, and i got mostly 1 ft. sectional track with the original or homemade connectors.
so soldering a jumper from feeder to rail where locos don’t run, is less work than jumperwires at every joint.

but if i can use my groundwire as common for everything (8 circuits trackpower, 16 switchmotors with 32 reeds, houselighting plus some animations) then it will not be wasted money. :wink:

#4

Korm,

In this diagram when one power supply is in “forward” and the other is in “reverse” won’t a short occur if a loco bridges the block and trips the circuit protection, or worse, burn the loco?

#5

I don’t think with a common return and two packs it’s possible to run them in opposite polarity. You need double insulation to do that.

#6

Jon,

why?

i thought, that each transformer just takes back the same polarity and current, that itself had sent out.
and if i’m right with that assumption, it should work.

#7

If they are 2 independent power supplies (already established), it is possible.

It won’t work if they have anything in the output stage in common.

Greg

#8

The idea with common rail is that the 2 packs can be set to different polarities and voltages. The trains can be independently controlled. Yes, if a locomotive were to try and cross that gap, and the polarities are opposite, then the locomotive would stop. Its probable that one of the packs would trip a fuse or breaker or whatever, but if the packs have that kind of protection then there should be no damage.

When I tried common rail, back in the 80’s, the packs I used didn’t use isolation transformers in them. They were El Cheepo packs that didn’t have any overload protection neither, and when my locomotive hit that kind of gap, the 2 packs were effectively shorted through each other. There was a loud bang and the lights went out. That’s all the experience I have with common rail. I rewired into standard blocks, replaced my power packs with non smoking models, and added a resettable circuit breakers into my circuits.