Am I correct that if I add a reverse loop (in NCE DCC) all I do is isolate/gap all 4 of its rail ends (which in this case will be between 2 switches in main; not the common loop which looks like a tear drop) and Hex Frog juicer will instantly switch polarity in loco as it enters and leaves this section ? ...Simple "yes" is fine..If "No", then why/how ?
It is best to show a layout drawing. A “loop which looks like a tear drop” will probably cause a short unless there are “isolate/gaps”. Bob
Mark - well that is a "yes and no" answer . A HexFrog juicer doesn't "instantly switch polarity in loco"; it switches the polarity of the track. And, in this case, you need to switch both rails (the Hex Frog can do this, but it is designed, by default, to switch only a single rail, per circuit, as it is primarily used on a switch's frog). Depending on the full design, it doesn't matter which side of "shorted" loop is reversed, but you need to ensure the gaps are placed so that all shorts are eliminated. On a "tear drop" loop, remember that the outer rails at the switch coming into the tear-drop are the same polarity, without gaps. This is why most people set the auto-reversing circuit within the tear-drop, with the switch being outside -- the gaps just beyond the switch.
I hope you won't mind my recommending you visit: http://www.barstowrick.com/category/wiring-reverse-loops-wyes/ Over the years here at TB, I've answered this same question in number of ways and decided to make it easy on myself and share the answer to your question in the format above. Yes, you always need to isolate both sets of rails on the reversing loop, isolating both rails on the diverging end of the switch. Bonus: To include a section of a wye or the turntable. Learn how-to in the link above. I hope that helps.
I run Z scale model locomotives from Marklin and Rokuhan, with DCC add-on boards. I found that the Marklin locomotives did not always trigger an automatic reversing module. Since the turnout into and out of the reversing unit has to be changed manually by sending an accessory command, in my case from an NCE PowerCab, I reversed the power using a NCE Dual Relay, which was triggerd by a NCE Switch It. This has the same effect as a manual double pole, double throw switch. The Switch It was assigned the same accessory address as the turnout, so triggering the turnout also triggered the Dual Relay and reversed the polarity. By wiring the power outlets so that the polarity was reversed outside the reversing loop it is possible to wire the track for either DCC (digital) or DC (analog), as BarstowRick explains in his web link. When running the track as DC, the accessories are still operated by DCC. This wiring was done on a little test set up, with everything visible. In this case, it is important to differentiate between the DCC wiring used for track power and the DCC wiring used for accessory control. Rob Pearce (aka ViperBugloss)
I know you have a solution, and a pretty clever one, but curious, what autoreverser did not trigger on your marklin locos? Greg
The main auto reverser I used was the Digitrax AR1. This has an adjustment screw on it but even at maximum sensitivity it would not always trigger. This was especially true with lighter Marklin locos, like the 88784 and 88787. I also tried a Tam Valley Dual Frog Juicer but with the same negative result. However, I have successfully used the Digitrax AR1 Auto Reverser with the Rokuhan/Noch locomotives on a slightly different layout incorporating a wye. These locomotives are somewhat heavier than the Marklin locos, due to the different motors that they use. Rob Pearce (aka ViperBugloss)
I think Tam Valley now has units with greater sensitivity, just for Z Also the DCC Specialties units work well on Z
