I'm going to have several loops on my layout and I was thinking there were some automatic reverse loop devices for DC block systems. Do any of you have experience with one of these? I don't like having to stop the train, swith directions on both the control panel and the throttle device then go. I want it to run smoothly through the loops. Advice?
Assume the block entering the loop is "A". Somewhere past the turnout on each leg you have two insulating railjoiners on the entering and leaving sections. The track between these two sets of railjoiners is block "B". If you have a reversing switch for each block, each with, say, an up and down position (or R/L), you set both up as the train enters the turnout. In one position of the turnout, the train will enter, in the other, it will not. To get it to enter in this position, reverse the direction of block "B" by flipping the switch down. When the train is in "B", simply reverse "A" and it will leave smoothly. There is no reason to stop the train, and you will soon know which turnout poisition corersponds to the both up, or one up one down position of the block switches. The "B" block should be long enough to give you time to reverse the "A" block control. If you wire "A" and "B" consistently, you will enter smoothly with the turnout in the straight position and both switches up or down. If you draw two rails you'll probably see how the + becomes - if it were not for the railjoiners and direction control.
Steve - did you mean continous hands off running? If so I have not tried any but I am thinking about it. I'd love to know what you find out. There is one company: CTI Model Railroad Computer Control System Which has a system that can be programed for multible hands free train running. Here is the yahoo group that has a lot about it: http://groups.yahoo.com/group/cti_users/
Wasn't there an infrared system that switched the polarity right when the train broke the beam? It would be nice to have that and a device that would stop a train after crossing the infrared beam, but as far as I know there isn't anything like that. Or is there?
Let me see if I can reconstruct what I built in about 1975 to do this. A train is traveling north. Before the entry to the reversing loop, you need a dectector. I used reed switches, and a refirgerator magnet on the bottom of a tender. The magnet closed the reed switch. The reed switch was connected to a dpdt relay and the switch machine. It set the polarity of the loop to "North" and the threw the switch to "normal." Just before the loop ended (just before you were re-entering the mainline in a "South" direction, there was another reed switch. When activated by the magnet, it threw the switch to "offset"--other than straightline normal. And it also threw the mainline direction to "South." So trains went around forever, automatically. My biggest problem was amplifying (or reducing) the current through the reed switches. With my guru electronics brother, I built an amplifying circuit that let the reed switches throw the much higher amperage switches and relays. I think today's integrated circuits must account for that amperage gain. The switching circuit is not that difficult to figure out (hey, I did it as a neophyte 30 years ago); I'm sure it's a topic in many MRR electronics projects books. You just have to control the reversin circuit of the dpdt relay.
QUOTE]Originally posted by Steve Mann: I don't like having to stop the train, swith directions on both the control panel and the throttle device then go. I want it to run smoothly through the loops. Advice? [/QUOTE] Steve, If you just want to run without stopping the train then see this thread for Hank's (Hytec) explanation of how to wire the loop. http://www.trainboard.com/ultimatebb.php/ubb/get_topic/f/9/t/005621.html#000000 If you want complete hands off operation, your options depend on your electronics ability. If you can roll your own, there are lots of simple optical block occupancy detector circuits that you can use to control a relay to switch your track power and operate your turnouts. I use them right at the ends of my sidings to shut off power so I don't overshoot the end and to operate signals as well as block detection . If you need ready-made, there are a few companies that make them for DC. Dallee Electronics is one of them, http://www.dallee.com/ and there was a guy selling them on ebay a few months ago. Nelson
