Replacing A Digitrax AR-1

A DCC auto-reverse unit allows operation under DCC to traverse reversing sections in wyes, reverse loops, and similar trackage without the need for manually reversing polarity in situations where rails of opposite polarity come together. They operate by sensing an electrical short in such a situation more quickly than a standard circuit breaker on a booster and reversing the necessary polarity before the circuit breaker sees the shot and trips.

I had a Digitrax AR-1 on a reverse loop for this purpose, but I was never completely satisfied with it. It was hard to set up, The AR-1 uses a " Tunable Trip Current Adjustment Screw" to adjust operation on a particular layout for whatever variables are involved. I found that when I first installed it, I had to fiddle with the screw to get it to operate correctly on my reverse loop.

On top of that, I was never able to get it to work with more than one unit in a locomotive consist. The first loco would pass into the reversing section, and once things were tuned, it would trip the reverser, and the single unit would run through the section. But when a second unit followed the first one in a consist, it would reverse the polarity again and cause a short. I don't know what the problem was, but fiddling with the adjustment screw didn't help.

I resarched the problem as best I could on the web, but i never found anyone talking about the exact situation I had. And from years as a computer tech, I don't have confidence in support lines. So I went looking for a substitute. It seems as though most people are satisfied with, or put up with, the AR-1.

Eventually I settled on the Tam Valley Depot Dual Frog Juicer, which is only slightly more expensive than the AR-1. The basic Frog Juicer works to change polarity on a single switch frog, under the principle outlined above: if it detects a potential short, it reverses polarity before the main circuit breaker can detect it and trip. The Dual Frog Juicer can be used to do this with two rails at once, so it's usable as an auto reverse unit. A jumper is provided that, when closed, will allow it to operate this way.

I swappped out the AR-1 with the Dual Frog Juicer this weekend, and after testing and some supplementary rewiring, it works fine, with single units and multiple units in consist. So I'm very pleased. I've used probably half a dozen Tam Valley products on my layout so far, with aboslutely no problem. No product defects, clear documentation, easy installation. Not every DCC supplier has this record with me.

I can use the AR-1 on a narrow gauge wye that will have only single steam locos operating on it, so I haven't really lost money.