# Simple back and forth



## lownote (Jan 3, 2008)

I'm doing some substantial revisions to our layout, and I wanted to add a "trolley line:" a simple automated back and forth line that would not be connected to the mainline. I'm a little confused about how to do it.

I have the NCE 10 amp system.

I'd like to connect this "trolley line" to my NCE command station. So the NCE would be running two separate tracks--the mainline, and the trolley line. Then I'd like to automate back and forth operation on the trolley line.

LIke this:











I'll put a decoder in whatever I decide to run on the trolley line, and then I'd like to set its speed and have it auto-reverse when it gets to the end of the line.

This should not be hard, right? I'm thinking that I would need an autoreverse unit like the PSX-AR. I'd isolate each end of the trolley line, and then wire the small isolated section in reverse, so that when the "trolley" hit the isolated section it would sense a short, and reverse polarity. Would that work? Ideally, I'd like a smooth, slow stop and start, and maybe the ability to time the reverse.


I know one way to do this would be to hook the entire layout to a laptop and run it using JMRI, but for a variety of reasons I don't want to do that.

Suggestions welcome, and thank you


----------



## Daniel Peck (Mar 31, 2009)

Dallee Electrionics has something that would work


----------



## Dennis Cherry (Feb 16, 2008)

Check out this website. 

http://dccbitswitch.com/Reversing.htm


----------



## lownote (Jan 3, 2008)

Dennis that DCCBitswitch website looks interesting--thank you. I also maybe be able to just do it with that NCE mini-panel. Hmmmmmmmm


----------



## Trains West (Oct 4, 2008)

in dcc polarty on the rail does not control drection if you try and use an auto reverser the trolly will run right off the end of the track......


a gold lenz decoder has trolly stuff built in


----------



## krs (Feb 29, 2008)

Posted By Trains West on 24 Dec 2011 07:46 AM 


a gold lenz decoder has trolly stuff built in 

I was going to mention that - not specifically the Lenz decoder but any DCC decoder that has the "trolley" function built in - I think there are several choices, but Lenz is certainly a good one.

If you need to buy a decoder anyway. that is the best way to go since you get a full-fledged decoder and can use it anywhere when you decide to no longer run a trolley line.


Knut


----------



## lownote (Jan 3, 2008)

How does the lenz controller know when to change direction--what triggers or signals it? Is it a physical "event" on the track, like a polarity change?


----------



## krs (Feb 29, 2008)

The Lenz decoder uses the Automatic Brake Control (ABC) feature triggered by an asymmetrical DCC signal that is generated using five diodes. 

There is some more detail here: 
http://www.tonystrains.com/technews/lenz-asy-abc.htm


----------



## lownote (Jan 3, 2008)

Aha! That Lenz feature is extremely cool! That would be a very simply way to accomplish an automated trolley line. Now I need to think of a way to automate a crossing. But that's another post


----------



## Dan Pierce (Jan 2, 2008)

On the Zimo decoders, look at CV27 for LENZ ABC control.


----------



## krs (Feb 29, 2008)

CV27 on the Zimo decoder provides only the very basic option of Lenz ABC braking control, it also doesn't provide the trolley shuttle option we are talking about in this thread. 
The only other G-Scale DCC decoders I can think of that have a 'shuttle' option built right into the decoder itself is the Uhlenbrock decoder (or the Dietz decoder or the Piko decoder, both of which are versions of the Uhlenbrock decoder. 
Those decoders use the INDUZI function for the shuttle control - shuttle opration requires one or two track magnets and a reed switch (connected to specific decoder inputs) triggered by the track magnet. 

Knut


----------



## krs (Feb 29, 2008)

Posted By lownote on 26 Dec 2011 01:33 AM 
Now I need to think of a way to automate a crossing. But that's another post 
Did you start a thread on that yet?
Not sure about your requirements.


Knut


----------



## lownote (Jan 3, 2008)

Well I managed to get the back and forth going, using the Lenz decoder. It works very well. The trolley stops, waits, and reverses at each end, simply by putting five diodes on one rail at each end of the track. Thank you for the suggestion. I have some tweaking to do with the timing, but otherwise it's great.

I should note that I tried it first on my bench (where it's warm!) using JMRI and a digitrax interface. I could not get it to work, but that's because the Digitrax unit barely produces enough voltage to move the loco. Once I tried it on the mainline, at 21 volts, it worked perfectly.


----------



## Greg Elmassian (Jan 3, 2008)

Yeah, had a similar thing happen, was programming using my PowerPro system, normally used for my Z scale. The USAT GP7 seemed really sluggish and took "too much" to get it running. Then remembered my PowerPro is putting out 13 volts! 

Greg


----------

