# Point to Point Auto Reverse



## Florida Trains (Jan 7, 2013)

What is the most reliable, easiest and cheapest way to wire a point to point auto reverse circuit for a street car or trolley? Diagrams appreciated. This will be outdoors and needs to be weatherproof.


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## Greg Elmassian (Jan 3, 2008)

easiest is not cheapest and vice versa.

put these 3 in priority order:

easy
cheap 
reliable

and your question can be answered.

Greg


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## dbodnar (Jan 2, 2008)

*Some AutoReverse Options*



Florida Trains said:


> What is the most reliable, easiest and cheapest way to wire a point to point auto reverse circuit for a street car or trolley? Diagrams appreciated. This will be outdoors and needs to be weatherproof.


I have designed and built a number of such circuits over the years. Here are some links:

The simplest: http://www.trainelectronics.com/Reverse_loop_dual_coil_relay/ 

With microcontroller:
http://www.trainelectronics.com/autoreverse/autoreverse.htm

Most sophisticated:
http://www.trainelectronics.com/autoreverse/basic/NEW_unit.htm

Same as above but with Arduino:
http://www.trainelectronics.com/Arduino/BARC/

For DCC with Arduino: 
http://www.trainelectronics.com/DCC_Arduino/DCC++/IRThrottle/index.htm 

All of the above are reliable - cost varies quite a bit - as to leaving them outside, I don't recommend it for any electronic devices - better to attach easy to remove plugs and take such things inside, at least for the winter.

I hope that helps.

dave


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## Homo Habilis (Jul 29, 2011)

You might find this thread, Back and Forth Auto Controls for Train Display Need Ideas, of interest.


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## Greg Elmassian (Jan 3, 2008)

Well, if "Florida Trains" is indeed in Florida, then temperature extremes probably will be secondary to keeping moisture out of the electronics.

He's got quite a shopping list now, we'll see how the priorities of cost over simple pan out.

Also, we'll probably get a calibration on cost/effort on building your own, as opposed to buying off the shelf.

"Florida" I was not trying to give you a hard time, but so many new people want it high quality and low cost, it's funny, and really not doable.

Surely you would not walk into a Mercedes dealership and ask for an economy car. Nor would you buy a used Yugo for the 24 hour endurance race at Le Mans.

I was indeed trying to give you a framework to think about how to decide what is "best" for you GIVEN your priorities.

Let us know how your decision process goes.

(perhaps you should set a budget limit and also state if you would build one yourself from electronic components)

Greg 1,051


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## toddalin (Jan 4, 2008)

This is actually the easiest way to do it and is the basis of most commercial circuits. I've built and use several of these and actually built three right into my control panel for each of my three throttles allowing me to run p-t-p for any number of applications around the railroad.

This shows it powered by the power pack and uses a 12 volt regulator. I do it with a 6 volt regulator and a 6 volt relay. Some (those in the panel) use a dedicated 6 volt source while others out on the railroad just use the track power with bridge rectifier and a 6 volt regulator. Because I always run the trains at more than 8 volts, this is not an issue. Also, I use 1K for R0 and omit R1. That way, the timing is most similar in both directions (0.1% difference). I don't really want it to be longer one way than the other and 1K is the minimum value that can be used in this position without overheating the chip.

You also need a diode at the end of each side of the length of track as shown in Dave's schematics.


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## Florida Trains (Jan 7, 2013)

Thanks everyone for your review and replies. I will research your recommendations and endeavor to find a solution. My initial "gut feeling" is to put in a loop of track and just let the trolley continually circulate.


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## Florida Trains (Jan 7, 2013)

This is what I decided on. It appears to be easy to install. Ordering from Shourt Line
*G Scale LGB 10345 Automatic Shuttle Train Circuit Set  NEW + A Free SL Precision Throttle and bridge*


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## Greg Elmassian (Jan 3, 2008)

Whoops, put in autoreverser unit, not shuttle unit, nevermind..

Greg 1,039


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## toddalin (Jan 4, 2008)

Totally different animal.

However, if it is cost savings you are interested in, you can build the circuit I provided for well <$10 with the difference being that you won't get the accelleration/decelleration at the ends.

But even this can be overcome for cheap with just an insulator and resistor or a few diodes at each end to make a "slow-down" section before the stop.


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## Dan Pierce (Jan 2, 2008)

I do not think the 'rpaisley' circuit can be done for $10 by a newbie with no parts on hand. 
To average $10 all the parts would have to be bought in quantities. Also the 7812 needs a .01 glass cap for noise filtering!! I always add this to my regulators per the spec.

Of course, I have all these parts just hanging around and could build it from my 'junk' bin/box for nothing, but I did buy many of these parts in quantity for repairs and other projects in the past.


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## Greg Elmassian (Jan 3, 2008)

Dan, you said " .01 glass cap" but I'm sure you meant 0.01 disc cap, or ceramic disc cap.

I agree on the parts cost.

Greg 1,027


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## toddalin (Jan 4, 2008)

You guys need to learn where to shop. Go to the bay.

Sure you may have to buy in quantity...,

...But at just $0.31/10 diodes ($0.031 each) w/free shipping.

555 chips at 20/$1 ($0.05 each) w/free shipping

LM7812 at 5/$0.77 ($0.065 each) w/free shipping

circuit board 5/$0.21 ($0.042 each) w/free shiping

etc., etc., etc.

Most expensive part is the dpdt relay ($1.19 for a 10 amp relay)

You could make a bunch for <$10 with no parts on hand.


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## Florida Trains (Jan 7, 2013)

Florida Power and Light has asked me to stop manufacturing electronic boards and soldering.


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## Greg Elmassian (Jan 3, 2008)

Sheesh, they're no fun!

Greg 1,018


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## barnmichael (Jan 2, 2008)

SplitJaw makes a nice reversing unit. http://www.reindeerpass.com/Split-Jaw-Point-to-Point-Reversing-Unit-Model-100-B-2-Amp.aspx


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## Greg Elmassian (Jan 3, 2008)

Michael, note post #8 where he states what he bought.

The rest of us are rambling on costs/ease of other alternatives.

The question of priority of cost vs. easy vs. reliable was requested but never answered.

So the rest of us are just messing around.

Greg 1,004 (going to 3 digits today)


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