HELP! I finally got the nerve to tackle a GP9 (g scale) with a DH580. I got everything back together, and life is good. Except one thing. In DC mode, when you change polarity (forward/reverse), the directionals would go from green/red, depending on direction. I.e. if you were going forward, the directionals would be green in front, red in rear, reversed for reverse.

So, HOW can I fake a polarity change in DCC? Digitrax says it can't be done. I'm thinking that this is a programmable chip...there HAS to be a way using CVs 49-56...and I can't be the only person who's dealt with this. Any ideas? Thanks in advance, Bill

-- Bill Oakes (bill_oakes@triton-images.com), June 01, 2001

Answers

The simple minded solution is to wire the directional lighting off of a DPDT relay with the coil wired to run from F0 and the contacts wired as a reversing relay. The DC power for the lighting can be wired from another function.

BTW, don't be too suprised if the Digitrax decoder turns to slag. Its not up to the load of a GP-9. The motor stall currents can be as high as 15 amps EACH. I've toasted two DG580L's in RS-3's that draw about half the current of a GP-9. You might have better luck with an NCE D408SR.

see http://www.trainweb.org/girr/tips/tips5/dcc_tips.html#stall

-- George Schreyer (gwschreyer@usa.net), June 07, 2001.