Quote from: Chris G on October 15, 2007, 11:22:53 PM
Hello Bill,
Thanks for the input.
Correct me if I am wrong but I take it that when you power the frog thru the Blue point you are actually powering the switch rails, closure rails and frog with the same polarity ?
You only need to isolate the frog then if you get a short running a large loco thru the points and it shorts out by having wheels of the opposite polarity touching the switch rails, closure rails or frog ?
I've now got my blue points in hand and do not want to do more than I need to get good operation. Hence my cautious approach and lots of confirmations.
Send me an email if you lik and I will reply with a photo of the points I am using just in case there is a difference.
Thanks Chris
Hi Chris,
Yes, that's correct, on my modules, the BluePoints are powering the frog, and the frog feeds the closure rails and the points. The main stock rails are powered by the main feeder wires, not the Bluepoints, and except in the case of the Auto-reverser section, their polarity doesn't change. This does leave the possibility for a wheel's back surface to touch the open point as the wheel passes through, thereby creating a momentary short which, using DCC, would be enough to cause the breaker to shut down, but this hasn't happened yet. The clearance between the open point and the stock rail is pretty generous, so I don't think it's a problem, but as I said, we haven't tested any of the MMI K's which have a long wheelbase that may cause a problem. Of course, if you gap the closure rails close to the frog, and add jumper wires from each closure rail to the adjacent stock rail, making the points always the same polarity as the stock rails, you would eliminate the possibility of a point to wheel back short altogether. I didn't, because I was working under a deadline to have the module operational for a show, and I figured with small radius curves I probably wouldn't be able to run anything that would cause a problem, anyway. At the time I built the first module, which is an equilateral wye mounted on a hexagonal table less than 36" across, the biggest locos available were able to traverse an 18" radius. Since space was an important consideration, I used 22" radius for the curved track between the 3 Peco "wye" turnouts (approximately 35 degrees). I was a little concerned when I purchased one of Bachmann's Forneys sometime later, but fortunately, it seems to run OK through the wye module. If I had it all to do over again, I would use at least 24" radius as a minimum, possibly even 26" or 28". I also might use Micro Engineering turnouts since I'm not fond of the look of the stubby Peco ties and the "brassy" color of their code 100 rail, but operationally, however, I'm happy with the Peco turnouts and the BluePoints. I would use the BluePoints again, no matter which brand of turnouts I choose.
Regards,
Bill Nielsen
Oakland Park, FL