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My layout is at a stage now where i wish to put in 3 passing loops, these loops will be sited in part of the roof space that cant be seen when operating the layout, i have 3 running tracks that pass into this area, and i would like to install passing loops on them so that when one train enterers the tunnel, it goes onto the loop, triggers the points to change and thus allowing the train on the other loop to go forward,and the initial train to stop if i can achieve this, it would allow 6 trains to operate (3 at one time) while i operate the engine sheds and shunting yards.
I would like this to operate automatically and reliably with the loco,s all on DCC, i did try this once before but with locos only on DC operation, although it worked, it was unreliable, this was operated with reed switches & magnets, and i dont want totake that route again. Any help and avice of what to do and not do would be gratfully recieved
 

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Paul Hamilton aka "Lancashire Fusilier"
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Thunder, an occupancy detector will do exactly what you are after. I am a digitrax man myself but I know Richard Johnson of DCC Concepts has a nifty light based occupancy detector that will work for this application.
 

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QUOTE (Thunder @ 19 Oct 2008, 15:16) <{POST_SNAPBACK}>i did try this once before but with locos only on DC operation, although it worked, it was unreliable, this was operated with reed switches & magnets, and i dont want totake that route again. Any help and avice of what to do and not do would be gratfully recieved

Where was the unreliability ? - the first automatic passing loops on St.Laurent were operated using reeds, magnets & relays - the unreliability problems we had were confined to the peco points - once we replaced all the track & points to Fleischmann Profi we found that the storage loops worked with a very high degree of reliablity. (We will be at Beckenham this coming weekend, if you want to have a chat).

It's very easy to do, especially if the loops are "off stage".
 

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Just another modeller
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QUOTE (Brian Considine @ 20 Oct 2008, 15:17) <{POST_SNAPBACK}>Where was the unreliability ? - the first automatic passing loops on St.Laurent were operated using reeds, magnets & relays - the unreliability problems we had were confined to the peco points - once we replaced all the track & points to Fleischmann Profi we found that the storage loops worked with a very high degree of reliablity. (We will be at Beckenham this coming weekend, if you want to have a chat).

It's very easy to do, especially if the loops are "off stage".

***I agree they can be easy enough to get right if simple rules are followed... but things have to be done right:

Reed switches have a specific orientation in which they work best, magnets have to be properly positioned in relation to the spec of the particular reed switch too.... easier now with neo magnets which are smaller and stronger, but with older ferrites it was easy to be hit and miss.

Richard
 

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I have 4 passing areas. 2 are purely for passing off scene and 2 in my station (See blog for layout)

I want the very same as you describe both in the station and passing points. I recently ordered IRDOT-P from Heath-Cote electronics. These use IR to detect a train, switch the power and the points to another line. Once wired in, I will be able to operate the points either manually or allow the detectors to operate the points by automatic detection.

Hope that helps.
 

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Just another "point" - if only automatic operation is envisaged the trailing points, dependant on the type may be able to be left unmotorised.
 

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Discussion Starter · #7 ·
Many thank to all for taking the trouble to reply, The occupancy detector mentioned by Lancashire Fusilier sounds intresting, and may be exactly what I require. with reference to the reed and magnet system, i did find that it was not always possible to position a magnet under a loco, and they often failed to trigger the solenoids that activated the point motors, i found it fiddly and time consuming, maybe it was how i installed it? I would be intrested to hear how eddscot gets on with his installation, and how good it operates, finaly i dont think i would have any loose trailing points, this would not allow me to have trains running in opposite directions if required?
 

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Hi All

I used the same setup that Brian referred to

The Fleischmann points are sprung - so if left normally curved - a train traveling on the straight line will force its way through
the trailing point- If going the other way it will follow the curved path.

With "on stage" automatic operation it is better to utilize "Brake on DC" or "Asymmetrical DCC" (same kind of thing different name) This can be triggered with any type of detector
Allowing the train to slow down to a stop (its normal program for deceleration) rather than cutting the power and coming to an instant dead stop

Regards Zmil
 

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QUOTE (zmil @ 21 Oct 2008, 02:48) <{POST_SNAPBACK}>The Fleischmann points are sprung - so if left normally curved - a train traveling on the straight line will force its way through
the trailing point- If going the other way it will follow the curved path.

With "on stage" automatic operation it is better to utilize "Brake on DC" or "Asymmetrical DCC" (same kind of thing different name) This can be triggered with any type of detector
Allowing the train to slow down to a stop (its normal program for deceleration) rather than cutting the power and coming to an instant dead stop

Even if the points can be pushed over in this way they need to be "dead frog". The "live frog" or "electrofrog" type will cause a short circuit if set wrongly as a train approaches, before the train can push the blades over.

"Asymmetrical DCC" also known as "ABC" is only supported on certain decoders. It is possible (but I've never tried it) to set the decoder up to give a constant stopping distance regardless of the initial speed. Brake on DC is probably more widely supported but again you need to check the instructions for the decoder types you use or plan to buy. In either case you need to detect when the train has reached the position to start braking and then switch the track under the whole train to asymmetrical DCC or DC. This allows for the situation where the motor is not at the front, and also prevents powered or lighted coaches or even metal wheels bridging between the normal DCC and the braking section. This will affect the brake application and in the case of brake on DC could cause a short circuit.
 

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Richard Johnson mentioned this to me regarding slowing down whilst on scene rather than dead stop. The IRDOT-P as I understand will be dead stop as the power and points are switched at the same time - although having said that I have also bought a timer which I think allows a little time in between one line activating and the other to prevent false detections. I'm sure this can also be used to allow a slow braking effect (using the decoder) before the points switch.

I also have this link http://www.dccbitswitch.com/ which I believe has details of how to have a braking system.
 

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QUOTE (Edwin @ 21 Oct 2008, 07:54) <{POST_SNAPBACK}>Even if the points can be pushed over in this way they need to be "dead frog". The "live frog" or "electrofrog" type will cause a short circuit if set wrongly as a train approaches, before the train can push the blades over.

"Asymmetrical DCC" also known as "ABC" is only supported on certain decoders. It is possible (but I've never tried it) to set the decoder up to give a constant stopping distance regardless of the initial speed. Brake on DC is probably more widely supported but again you need to check the instructions for the decoder types you use or plan to buy. In either case you need to detect when the train has reached the position to start braking and then switch the track under the whole train to asymmetrical DCC or DC. This allows for the situation where the motor is not at the front, and also prevents powered or lighted coaches or even metal wheels bridging between the normal DCC and the braking section. This will affect the brake application and in the case of brake on DC could cause a short circuit.

If you want to use any type of decoder then you can use a "braking module" - this will enable the locomotive to slow down & stop in the section.

The constant braking distance feature of some decoders is very effective when set up correctly.
 
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