# Tying two systems together



## 2tall (Nov 18, 2011)

Hi Guys
I'm in the early stages of this go on forever hobby and I have a question, I have an HO system with an outside loop and inside loop and got the bright idea of hooking them together but using two separate Power supplies. I put a gap between the two turn outs with a DPDT switch so I can tie them together or separate the two loops. My question is when I close the switch I'm backfeeding 12 volts to the other power supply, will that damage it? can I use diodes to pevent the back feed? 
Help please, thanks 2tall


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## sstlaure (Oct 12, 2010)

Put insulators between the sections (or blocks) What you're talking about is block wiring - very common in regular DC.

Basically you would have 2 blocks, and each could be powered by either power supply (either A or B, but not both.) 

Call Block 1 your outer loop, and block 2 your inner loop. You would have power supplies A & B.

You wouldn't have any trouble running the trains around separately, but as soon as a train bridges the gap between the (2) blocks, you could run into problems.

If the trains are going opposite directions, you'd get a short (front truck picking up one voltage, rear picking up the other power supply with their polarities being opposed)

If they are going the same direction, as soon as the train from block 1 moves part way onto block 2 it would start getting input from both and would take off in speed (or possibly burn out due to too much voltage being supplied.)

You'd be better off having an inner loop, an outer loop and a transition track between them which would allow you to switch from A to B power supplies and switch the trains as you're moving from block to block.

If you really want to run 2 trains truly separate in the easiest manner possible - go DCC.


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## 2tall (Nov 18, 2011)

*Tying systems together*

Hi Scott
Thanks for your input, I can't afford to go to DCC at this time, retired and just having fun playing with what I have. Are you saying the block between the two systems should be longer than one small gap? I understand the polarity issue, for now what I do is run the train past my gap with the other power supply turned off. then I open my switch and turn on the other power supply and then take off on either the inner or outer track.
thanks Ron


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## NIMT (Jan 6, 2011)

Maybe this will help? This is what Scott is talking about.


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## Southern (Nov 17, 2008)

sstlaure said:


> You wouldn't have any trouble running the trains around separately, but as soon as a train bridges the gap between the (2) blocks, you could run into problems.
> 
> 
> If the trains are going opposite directions, you'd get a short (front truck picking up one voltage, rear picking up the other power supply with their polarities being opposed)
> ...


_Two tracks, two blocks, and two transformer, Is very easy._


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## Southern (Nov 17, 2008)

This is all you need. an Atlas 215 selector










With this you can run either track from either transformer.
I to run DC. DCC is one very costly leap for me.


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## sstlaure (Oct 12, 2010)

It is easy to wire, all I was explaining is if he has trains running on both tracks (Engine 1 controlled by Cab A and Engine 2 controlled by Cab B) and tries to cross one from Block 1 (Cab A) into Block 2 (Cab B) - he's going to see the engine controlled by the one set to the higher power (but not necessarily the one he wants to be controlling the engine with.) If Block 2 is set to Cab B, then both trains would then be powered by Cab B at that point and he may very well not have enough power for both (or they run at different speeds but you can't slow 1 down vs the other, etc)

The train won't just go back/forth if it's crossing between the 2 tracks - it will short out between the 2 tracks if they are set in opposite polarity (unless all of the power pick-up wheels clear at the same time.), or will continue through being powered by the other powerpack if they are set in the same direction

My engines have all wheel power pick-up and simply short out in the situation of opposite polarity. Thomas will go back/forth as all of the wheels clear the short fast enough to not trip the switch (my powerpack sends up a red light in a short and cuts power if it's detected for a short period of time.)

I had tons of selector switches on my old layout and ran it with 2 powerpacks. I found that trying to follow 2 trains around the layout switching back/forth from Cab A to Cab B was a pain in the butt.


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## 2tall (Nov 18, 2011)

*Tying two system together*

Hi Guys Thanks for all the great info. I just want to run a train from one loop to the other so I don't have to take them off the track by hand and put them on the other loop. I think to make it easier I would just park the train on loop A in a siding and then make my crossing using the diagram you posted. 
I sure have a lot to learn about train wiring, thought I could just do it myself but it wasn't working to well, must be hard headed at my old age.

Found a great web site on train wiring www.blockmaster.com
Thanks Ron


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## Southern (Nov 17, 2008)

This is at the point of two blocks of track. Each block is at full power and in opposite direction!





 
Don't try this at home. This very hard on the locomotive.


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## NIMT (Jan 6, 2011)

Southern, That's a hoot!


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## Southern (Nov 17, 2008)

That is a manta / tyco that runs super fast. I would never do that with an engine that I cared about, even if it is a one of a kind paint job.


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## 2tall (Nov 18, 2011)

Hi Southern
Thanks for the info on the 215 awitch, I got one and using my ohm meter now see what your talking about. If I run both loops A & B on say one cab or power supply, have both on about the same power level I should be able to traverse from loop A to loop B with now problem is that correct? also It looks like I could use the 215 switch for my dead end turn outs to park trains and then turn off that section of track. I want to install signal lights on my turn outs to show when that portion of track is on, is that hard to do?
Thanks 2tall


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## Southern (Nov 17, 2008)

2tall said:


> hi southern
> thanks for the info on the 215 awitch,
> _your welcome, glad to help._
> 
> ...


 . .


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## 2tall (Nov 18, 2011)

Hi Southern
With your help I'm finally starting to get this wiring thing, if we use signal lights on a dead end turn out it would be easy to make the green light come on but the red light might take a relay. 
Maybe there are some guys on train forum that could help with signal light wiring.
Excited to get back to the layout, 2tall


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## NIMT (Jan 6, 2011)

Do you need a drawing of the circuit for how to do it?


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## JohnAP (May 4, 2011)

Sean,

You know we love pictures and drawings!


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## 2tall (Nov 18, 2011)

*Tying to systems together*



NIMT said:


> Do you need a drawing of the circuit for how to do it?


Please give use that drawing for signal lights.
Thanks 2tall


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## Southern (Nov 17, 2008)

2tall said:


> Please give use that drawing for signal lights.
> Thanks 2tall


 
yes please. I have the lights just never hooked them up. It would be great to have a circuit that switched the lights from green to red with the reversing of the polarity of the track.


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## 2tall (Nov 18, 2011)

*Drawings for signals*



NIMT said:


> Do you need a drawing of the circuit for how to do it?


Dear NIMT where are the drawings for the signal lights, sure would be fun to have them.
Thanks 2tall


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## NIMT (Jan 6, 2011)

Working on them now...Keep your shorts ON!
2 Tall wants turnout power indication, and Southern wants main line directional indication right?


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## 2tall (Nov 18, 2011)

*Signal lights*



NIMT said:


> Working on them now...Keep your shorts ON!
> 2 Tall wants turnout power indication, and Southern wants main line directional indication right?


Yes on 2tall, can't speak for southern but would like to have main line tooooooooo.
Thanks 2tall
My shorts are still on, at least I can where shorts in CA this time of year, just kidding.


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## NIMT (Jan 6, 2011)

I'm working on it.. should have it done here shortly!


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## 2tall (Nov 18, 2011)

Hi Guys
Are we making this harder than it has to be, I tried one gap or block between the two loops on the transition track, set both cab A and B to the same polarity and power and then drove my engine from loop A to B no problem. I'm going to set up two polarity sensative led lights to each loop, when both lights are either on or off just drive across.
What have I forgotten with this idea or will it be fine?
Thanks 2tall


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## NIMT (Jan 6, 2011)

There are three limiting factors to using LED's hooked directly to the rails.

First the voltage on the rails is variable, to make the LED light at a low voltage/amperage will cause it to overload at a high voltage/amperage.

Second to achive a directional/or polarity readings you will have to isolate both rails and not have any common connections. Reverse polarity is also very hard on LED's.

One mistake in setting the Joining rails to a common setting might very well turn your LED into a flash bulb!

Gunrunnerjohn put up one circuit that would help but the whole problem is not an easy one.


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## 2tall (Nov 18, 2011)

*Using leds*

Hi 
I do have both rails isolated, I can run loop A in one direction and B in the other with no problem. I didn't know there may be a problem with the LEDS but they are working ok now, hope they don't explode. 
Is there another way to use lights to show polarity on tracks, relays maybe?
2tall


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## NIMT (Jan 6, 2011)

Relays are a good way of sorting out some of the issues, but not a compleate answer.


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## 2tall (Nov 18, 2011)

Hi Guys 
Are there any other opinions out there, tried wiring like the attached drawing but didn't work to well, maybe because I'm also using Atlas switches and followed the wiring diagram. With there diagram both commoms are tied together on Cab A&B, this really makes things simple for dead end turn outs, I can park a train and turn off that section with one wire.
Thanks 2tall


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