ok...that was pretty much gobbledegook.... except the DPDT switches.... whats all that stuff do? I'm guessing that on a reversing loop with DCC you are still gonna have to stop your loco, throw the switch (or reverse polarity somehow), then take off again.
Sorry, I didn't mean to speak gobbledegook. I don't know your background or knowledge base. With a normal DC layout you use 2 DPDT toggle switches to control a reverse loop: one to control the track polarity of the loop and the other to control the track polarity of the rest of the layout. Before a train enters the reverse loop, at the point where the train enters the loop, you must make the track polarities the same. Once the train is in the loop you reverse the polarity of the rest of the layout so that when the train exits the loop the track polarities are the same at the exit point. If you don't flip the correct toggle switch at the correct time you will end up with either a short or the train will start backing up. With DCC, you still have to worry about shorts but you don't have to worry about the train backing up. The direction of the locomotive is controlled by the decoder in the locomotive not the polarity in the rails. The devices I mentioned (PSRev, MRC Rev Unit, Digitrax PM43, Boosters) delete the requirement for the toggle switches. These units work as follows: As a train enters or exits a reverse loop, if a short occurs, the module instantly (or close to instantly) reverses the polarity of the track in the reverse loop. As an operator you don't see any change in the direction or speed of your train. If you are using a non-DCC decoder equipped locomotive then you can not use it in the reverse loop where polarity is controlled by one of these devices. The changing of polarity by one of these devices will cause the locomotive to reverse direction. The locomotive will enter the reverse loop but it will never leave. The devices: PSRev - This is completely solid state device that combines short ciruit protection plus reverse loop control. To hook it up you have two inputs (Rail A and Rail B) and you have two outputs (Loop Left Rail and Loop Right Rail). It also provides LED indication of reverse function or short circuit. Also, a remote LED and toggle switch can be hooked up to the board. The remote LED duplicates the board indications while the toggle will let you shut power completely off to the reverse loop. The MRC Rev Device is also a 2 wire in 2 wire out but it uses a physical relay. It does not provide short ciruit protection. The Digitrax PM42 incorporates reverse loop support along with short circuit protection. This device support 4 separate zones and/or 4 separate reverse loops. It has a lot of wires running to and from it including external power, ground, and LocoNet connections. It also requires programming it just like programming a decoder. It uses physical relays. For more information go to http://www.digitrax.com. Boosters - Most boosters include a reverse loop output. On the booster you will see outputs to Rail A and Rail B and then two more outs, Loop Right Rail and Loop Left Rail (markings will vary). I am not sure of the mechanics for this since I have never used it on my boosters. I am sure there are other devices out there but these are all I am familiar with. I hope that wasn't all mishmash. David [ 15. October 2003, 16:18: Message edited by: ncng ]
