About a year ago, I was tremendously impressed by Lenz's Gold decoder, so much so that I haven't bought anything else since (as far as I remember) with the exception of a few N gauge products. My enthusiasm was based entirely on the excellent running qualities exhibited by locos fitted with these items, and I didn't really look at any of the other benefits. Features such as Automatic Braking Control didn't interest me as I'd already got them well covered with computer software - what was the point of spending money on extra gizmos to duplicate facilities I'd already paid for?
However, some of these features cropped up in online discussions this week, and as soon as Nigel Burkin mentioned he was considering employing Automatic Braking Control in conjunction with Asymmetrical DCC to ensure operators of his layout were using the signals correctly, the penny dropped.
I won't go into what Asymmetrical DCC actually is, (you can read a brief explanation here) - suffice to say it's a cheap and easy way to regulate train movements in simpler signalling situations. Although Lenz will quite happily sell you one of their BM-1 Block Management modules, they also give you a handy online diagram showing you how to make your own using only 5 diodes. As everything else you need is already built into the Gold (or new Silver) decoders, this was immediately attractive to me - I've got hundreds of unwanted diodes hidden away in the loft.
Connect the arrangement of 5 diodes into the right hand rail, switch a few settings on within the decoder and you're in business. A train will slow to a halt at a red signal (using Constant Braking Distance if you've also set that up) and be held there until the restriction is cleared. The same arrangement could also be used to slow trains to a halt in bay platforms, or to prevent drivers leaving the same bays until signalling permits. A slightly different configuration of the decoder settings can give you a shuttle service, handy for automating those bay to branch fiddle yard moves.
Obviously such technology can't rival the sophistication and flexibility of software-driven solutions, but it's pretty damned good in simpler, low-cost situtations. It's not confined to train sets, either, I've already got sets of diodes installed at either end of my test track in order to shuttle trains back-and-forth for running-in/testing purposes. This is a typical example of what's always appealed to me about DCC - power, flexibility and more than one way to do things.
Asymmetrical DCC will work with any NMRA-compliant DCC system. However, it should be noted that only decoders with this built-in functionality can work in this way. As always, you need to keep an eye on the features you want when chosing your decoders.
Currently On My Stereo: Eels - Daisies of the Galaxy