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I'm planning an expansion to the mainline of our layout. One of the most popular things we run is an eggliner on a auto reverser. it's connected to its own lgb starter set transformer, with an aristo reversing unit. works great, people love it.

I would like to set up a crossing, so the eggliner track crosses the mainline. But I want an auto stop for the crossing, so the eggliner would stop when a mainline train was in the crossing. I need to keep the egg liner track on its own power supply. I think toddallin's bump a.s.s. system won't work, because it relies (as far as I can tell) on both tracks in the crossing being on the same power supply

I know this can be done with opto sensors, but I'm worried that it might be beyond me. Are there any comerial systems for doing this that anyone can recomend?

PS I've thought of converting the eggliner to batteries, and using an infrared detector on the front of the eggliner. I might end up doing that but I'd rather not
 

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Posted By lownote on 02/24/2008 6:46 AM

I would like to set up a crossing, so the eggliner track crosses the mainline. But I want an auto stop for the crossing, so the eggliner would stop when a mainline train was in the crossing. I need to keep the egg liner track on its own power supply. I think toddallin's bump a.s.s. system won't work, because it relies (as far as I can tell) on both tracks in the crossing being on the same power supply

Bump A.S.S. was designed to work with one or two  separate systems.  Makes absolutely no difference.  (I actually use it with three systems, though only two are used at any given time.)

I assume that you are referring to the original Bump A.S.S. and not the new revised simplified relay system I conceived a couple months ago.




The Tortoise Bump Accident Avoidance System (Bump A.S.S.) was designed to protect a 30-degree crossing where two trains running on separate loops would meet. This system draws off track power and makes trains wait for opposing traffic. As designed, the system works down to about 6 volts on the rails, so is fine for anything but an extremely slow crawl.  The system can be changed so that it can operate off its own power supply (even just a 6-volt battery) so trains can run at any voltage.

The system includes two detector and two timing circuits that are based on the 555/556 timing chip.

The detectors consist of short sections of rail sandwiched between Aristo-Craft track insulators. The rail is only long enough to fit in the gap between the two insulators pressed together, so any power loss to a wheel is VERY short (less than half of a turn-out frog). This rail has a feed to a bridge rectifier. The other side of the bridge is fed from the opposite rail. (I use the "common" rail). The sections of track leading to/from the insulated section have a jumper under the insulators to maintain continuity. When any metal wheel crosses the gap, it sends a pulse of electricity to the bridge rectifier.

The power from the bridge is fed to a 6-volt voltage regulator and this triggers a 6-volt relay. That's the detector circuit, plain and simple!!! Two are needed and they are installed on all four sides of the x-ing and are wired in parallel in groups of two for the two sets of tracks. They need to be about 3 feet before the crossing to allow traffic time to skid to a stop prior to smacking opposing traffic already in the x-ing. They also need to be installed far enough from the prior blocks to keep an engine/tender combination from routing power from the prior block through bridging through the wheels. If you are not using lighted cars or double/triple heading, 3 feet is probably plenty.

This relay pulse must then me "latched" and timed to allow for a train to pass. A 556 (twin 555s in one case) timing chip is used ($0.69 each Internet surplus or $1.50 at RS), but could be two 555s. With a couple resistors and capacitors, timing can be set at any length (from milliseconds up to several weeks).

A rectifier is also connected to the powered rail (actually input to the "block" being protected) and the common rail. This also feeds a 6-volt regulator that powers the 556 and subsequent relays/LEDs. The relay in the detector serves as the trigger to the 556 and when closed by the wheel bridging the gap, it starts the 556 timing. The 556 closes a 4.5 to 6-volt relay. The input to the blocks being protected is routed to the N/C contacts of the relay. When the relay is activated, it open the circuit to the opposing block and the opposing train stops prior to collision.

Using other contacts on the relay, the system includes green/red LEDs that show the status of the block and these are set up as target signals on the layout and on the structure that houses the system for instant verification of system status. I actually get yellow between the green and red signals by having the relay connect the green portion of the LED to a big capacitor when the signal changes to red. The cap keeps the green on for a moment and the combination of green and red produces yellow. These LEDs are also powered off the 6 volt regulated supply that feeds the 556.

BTW, if you are electronically and/or monitarily challanged, almost all of the parts (except the two relays, the chip,  a couple resistors and a capacitor) can be replaced with a simple 6 volt wall wart and the system will work regardless of the voltage applied to the rails.  ;) 
 

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Posted By altterrain on 02/24/2008 8:11 AM
I think Del Tapporo's critter control system will do what you want.
1stclass.mylargescale.com/DelTapparo/Criiter_Control.htm
-Brian

My "Enhanced Critter Control" in its present form cannot do this. However, with the addition of IR Range finding devices like I use on my "Rail-Bot", it could certainly be programmed to stop the Eggliner at the grade crossing and wait for the train to pass. Of course this would require converting the Eggliner to battery power. But the nice thing about battery power and autonomous control systems (in my opinion) is it is easier in the long run to put some electronics in a loco than adding track wiring, sensors, and protecting it all from the weather, maintaining it, etc. With this modification, you would still have all the other Critter Control features available to you: back and forth trolley operation, as many station stops as you like in either direction, controlled and selectable accel and decel rates, speed control, etc.
 

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If cost was no problem and IF parts were still available, 8 LGB track contacts (LGB 17100) and 2 LGB switch drives (LGB 12010) with contacts (LGB 12070) can do this. The motive power must have LGB magnets (LGB 17010) or equivalent installed under them. Although switch drives are used, switches themselves are not needed.

The two paths through the LGB crossing, whether 30 or 90 degrees, are separate. Both routes plus approaches must be isolated from the rest of the circuit. Only one rail needed be so insolated so only a single contact will be needed to isolate a rail from the rest.

8 LGB track contacts control the power by flipping the switch drives first one way, then back. The contacts on a switch drive supply the power to one of the isolated crossing routes, the contacts on the other drive supply power to the other route.

The operation is thus:
As 'Train A' approaches the crossing, it crosses a contact that applies power to the crossing route (i.e. it 'drops out the switch drive or relay controlling 'Train B'. (This seems illogical but it's necessary because of bi-directional travel as will be seen later on.) This contact must be placed a 'train length' from the crossing.

At a stopping length for 'Train B' from the crossing, a second contact is placed which will flip the switch drive for track B, de-energizing the approaching tracks and crossing for track B.

After traversing the crossing, 'Train A' passes a third contact that does exactly the same thing as the second contact. Again, necessary because of bi-directional travel. The contacts essentially are wired in parallel.

At a train's length from the crossing, 'Train A' passes a fourth contact that does the same thing that the first contact did; i.e. drops out the switch drive for track B thus energizing the track for 'Train B'. 'Train A' can now enter a reversing loop or enter a reversing section.

The sequence for 'Train B' is the same, except the contacts are controlling the other switch drive and its contacts are controlling the approaches and crossing for 'Train A'.

The voltages for the two 'trains' can be from the same source or from separate power sources.

The voltage supply for the switch drives can be from the same supply or from a separate source.

Latching relays with at least one contact can be used instead of LGB switch drives. Contacts 1 and 4 would control the unlatch coils, and contacts 2 and 3 would pick up the latch relays.

I know a lot of people do not like to stop their locos suddenly. My first LGB Mogul was purchased before 1990 and has been stopped abruptly many, many times. It's still going strong. (Cross my fingers and knock on wood!)

Art
 

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Discussion Starter · #9 ·
Thank you very much everyone and I hope I can have a bit more of your patience and time.  It looks to me like all the methods of doing this (except Del's battery power method) would stop the functioning of the Aristo auto reverse unit--do i have that wrong? 

I like the idea of the infrared emitter/detector, but how waterproof/rugged is it? Dave Bodnar's idea of putting the two next to each other and using reflections is good--you could hide the emitter and the detector and the electronics in a single trackside building and keep them out of the weather.


Del's solution would be great but I'd end up with a very expensive eggliner! On the other hand, it'd be readily adaptable to, say, the trolley aristo is coming out with....
 

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Not at all.  The Bump A.S.S relay would go between the reverser and track and will have no effect on the reverser's cycle.
 
However, if the eggliner stops and waits for a train, while the reverser shifts, it would just go back the way it came without ever making it to the destination point.
 
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