Choice of System I started by examination of DCC systems based on what I believed I 'needed' back in April 2012 when I knew nothing about DCC but it sounded like a good idea and I had read a beginners guide to the subject. What was most daunting was the potential cost of decoders across a modest fleet of locos, most at the time very much pre-DCC (e.g. 1960s to 1970s) which would potentially require them to be heavier duty devices. My requirements were and are still simple, DCC just for driving locos, nothing else, not even sound, the following is an extract from Ref. 22.1 (Loco Conversions - 1 - DCC and Me), where I conclude that :- Extract: So DCC is good for me because :- 1) I can drive and park any given loco anywhere, 2) I can really drive a double header, 3) I can really drive a banker, 4) My railway can evolve easily and readily. With that in mind I really wanted a system that supported RF walkabout controllers for loco driving. Systems of the time included the Gaugemaster ProdigyWireless Advance 2, Digitrax Zephyr Extra Starter Set or the Super Chief Xtra Duplex Starter Set 8 Amp, none of these really appealed. In 2013 another contender came about, the Lenz Digital+ system which was much more favourable in terms of power delivery, facilities and types of controller. The RF frequency of American systems could be inappropriate for UK operation but the Lenz system from Germany meant I could use Wi-Fi components via their USB-Ethernet interface. This of course meant that I was not going to be tied to one particular proprietary RF system which may be supported with 'easy to use' hype can also be costly to the end user when trying to upgrade or replace failed equipment at a later date. So, connected a laptop via USB to the interface for decoder programming with JMRI Decoder Pro. Connected an Edimax WAP (wireless access point) to the Ethernet port which allowed WiFi access of TouchCab on an iPod Touch to communicate with the Lenz Command station. It was simple to do, for a change! So I put together a package specification and was able to get some 15% discount by diving in into the deep end to include command station, two booster amplifiers, mains transformers, USB & Ethernet interface and controllers plus a couple of decoders to get going with. The version of TouchCab available at the time worked well on old 2nd generation iPod Touch devices which were becoming available quite cheaply, much more cost effective than buying a few Lenz controllers, afterall, I didn't need their abilities for programming only loco driving. Further Refinements - Districts An aspect that bothered me was having power supplies that could deliver up to 5 amps into the track and woe betide an item that had a 2 to 4 amps flowing through it because of a fault, be it a loco motor or pickups, they just are not designed for that in OO gauge models. When a DCC command unit, booster unit does trip it is fast and can be programmed to attempt re-energising or not. Unless you happened to be driving and view the action that caused the short to occur you still need to re-energise to track it down. So automatically re-energising pulses the high current through the cause, still not very good. Also having everything running off of one psu or even 3 large ones means that a short circuit anywhere could cause a total shutdown if you configured a Lenz system accordingly, one unit shuts down they all shut down. Similarly if your points are DCC controlled from the same circuit and a loco shorts due to a mis-set point then the power effectively remains off and the points cannot be corrected. Ideally locos and points should be powered via separate DCC power units, or via intermediate breakers feeding separate buses. These two issues are easily overcome by splitting the railway layout into districts, a district is a distinct and electrically independent area of the railway which is powered via a dedicated programmable electronic circuit breaker. As a simple example, instead of e.g. one PSU delivering up to 5A to all areas 4 separate areas could be connected by 4 breakers each set to 1.25A which limits the damage to locos from high current shorts, an audible alert attracts attention to look at the visual indicators to determine in which area the fault occured. To this end the DCC Specialities - Powershield - X PS-X1 breakers were ideal, supplied as made up circuit boards to which you could add LEDs to indicate, power input ok, output ok, and short circuit present. They also had the option of fitting an audible warning device, which was somewhat cheaper if you ordered them from an electronic component supplier rather than a model shop. My estimates was to split the railway into 14 districts and package the breakers up to 5 at a time into electronic project enclosures, making use of all the LED and sound connections. I am really glad I did as it makes fault detection very easy to achieve. It also means that yard mishaps, the most common is to drive into incorrectly set points does not cause trains running on the mainlines to stop dead and concertina their trains across the tracks behind them I have played that concertina a few times when a train on the same district has tripped the breaker they shared. An alternative minimal cost approach to isolate faults is to supply each district from a common power supply via a switch each. In the event of a short circuit you turn off each in turn until the short circuit clears, however that does not remove the risk of excessive current damaging a loco whilst doing that. I preferred the DCC Specialities breakers because they used electronic components to perform the breaking, whereas at the time (2013) an alternative by Digitrax used relays. Locomotive Programming This was easier to perform using JMRI Decoder Pro running on a laptop, connected via a USB port to the Lenz USB interface which in turn connected to the Lenz Command Station. Storing locomotive decoder setup via the JMRI tools roster facility is a bonus. Summary So that is how I started off and the system has very much stood the test of time with few issues which primarily revolved around different versions of Lenz USB interfaces having incompatible software protocols. I had one basic setup for programming indoors and the main setup in the railway shed. However if I bypass the USB port and use the Ethernet port no problems at all. Lenz manuals are or were rather technical, but ultimately I am pleased with the system, it remains robust and reliable. References 2.1 Loco Conversions - 1 - DCC and Me https://platform1mrc.com/p1mrc/index.php?threads/dcc-loco-conversions-1-dcc-and-me.5557/ Next, DCC System Configuration Discussion always Jim Index of Articles with Links
