Dateline 7/13/05

The following, by Jim FitzGerald, appears in "Jim's Corner" in the July/August 2005 NTRAK Newsletter.

Over the past few years, I have been aware of concerns about the wiring and connectors called for in the NTRAK specifications. Our present specs date back to the original large layout at San Diego in 1974. We have tried to keep any change in NTRAK specs to a minimum and make it possible to continue to use all existing modules.

The proposed wiring and connector changes are optional, and all present modules can continue to be used without change. Most of this issue is in the form of Questions and Answers about the proposed Alternate Wiring and Connector Recommended Practices (RPs). Your comments are most welcome.

Please send to: ntrak@tcsn.net or Wiring RP, 1150 Wine Country Place, Templeton, CA 93465.

The Problem: 
Voltage drop with conventional throttles meant that trains would slow in parts of the layout, or block, that were furthest from the throttle, only to speed up as a block boundary is crossed. With DCC this could also mean loss or corruption of the control signal and that meant loss of control of a train.

Proposed Solutions:
John Wallis of the North Raleigh NTRAK club introduced the idea of using 12 gauge wire, as used in outdoor low voltage garden lights, to reduce losses. Since the Cinch-Jones (C-J) connectors that we use are designed for smaller 16 and 18 gauge wire, the club worked out ways to solder the heavier wire to the C-J connectors. This information was shared on the North Raleigh club web site.

Doug Stuard of the Northern Virginia NTRAK club found a connector that has been adopted as a national standard for DC power by Ham Radio operators. It was designed to take 12 gauge wire, has significantly lower resistance than C-Js and the individual contact housings can be assembled in different combinations.

Others suggested using the wire uncut from one end of the module to the other to minimize losses. Several ways of doing this have been suggested.

Some clubs have changed to other brands and types of connectors to address these issues. To study the whole problem, I asked John Wallis, Doug Stuard, Martin Myers (Baltimore NTRAK), Alan Schappell (Philadelphia NTRAK), Joe Ellis (Dayton NTRAK), Bob Gatland (Long Island NTRAK), Matt Schaefer (NVNTRAK), Brian Rebney (Michigan) and Brad Myers (Peninsula NTRAK) to help develop recommendations for an alternate set of wiring and connector specifications that could be used to improve our modules for both DCC and conventional DC throttles. Some other NTRAKers were also asked to join us, but did not reply. The RPs described here are the result of that effort.

Tests have been run which confirmed the lower resistance of the new wiring and connectors, both in simulations and in use on weekend NTRAK show layouts. Work is now underway on instructions for ways to achieve the best track power feeds without cutting the main 12 gauge stranded track bus conductors.

Modules that meet our long time specs can still be used in any NTRAK layout. With careful design, those specs work, as shown by the huge layout last year at Chantilly, VA. At the same time we are also suggesting that new construction and refurbished modules use the alternate wire and connectors. Although the wire costs a bit more, the new connectors are significantly less expensive, so the overall cost for wiring a module is less.

To preserve compatibility, builders who adopt the alternate wire and connectors will be required to furnish adapter cables fitted with C-Js, as is the current practice. This can be done using the old connectors to make the required adapters.

 


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