This question is for all the forum readers smarter than I am (which is anybody on the forums) about detection systems. Specifically, I am interested in using Bruce Chubb's optimized detection system for my layout. Reading his schematic leads me to believe that I need to have common rail wiring within each of the power blocks on my layout. Have I misread this? Your input greatly appreciated.
Old Fat Robert
Haven't a clue.
But.
If you DO need common rail, I recommend you build it with "non-common rail" up above, on the layout. And tie it together down underneath. That way, you can change back REAL easily. If you ever want to.
Ed
is this the Chubb schematic?
this is a more modern design that uses an NEC2506 opto-coupler to avoid the polarity issues.
both designs detect a voltage across the diodes in series with the track circuit to determine if something on the track is drawing power.
greg - Philadelphia & Reading / Reading
Greg: The diagram you posted is not the Chubb schematic. But I am going to save yours and do a serious comparison of the two.Thank you for your assistance.
The DCCOD is a transformer type, the one Greg posted is the original OD. The DCCOD, like other transformer detectors like the NCE BD20 or RRCirKits BOD-8, do not cause a voltage drop in the track since there are no diodes in line.
Like many other things in model railroading, terms are bandied about and the same thing used to mean different things. With block detection, the sensor almost always goes just one rail. That rail must be gapped between detection zones. The other rail does not need to be gapped. Between sections of track powered by different boosters, BOTH rails are gapped. You can do common rail, where one rail is never gapped, with DCC, but it requires opto-isolated boosters to prevent backfeeding power when trains cross the gap in the one rail. Just - don;t doo this. There's NO reason to ever wire anything like that. I never even wired my DC layouts like that, ALWAYS gapped both rails.
So sometimes it will be said that block detection is wired with a common rail. Not really. Just because one rail is not gapped except between boosters or different circuit breakers, it's not really common rail wiring.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Randy: I have a DCC layout with 6 power districts (obviously) gapped on both rails and I use Shinohara (not Walthers) power routing turnouts, so I have insulating joiners on both inside rails at the diverging end of the turnouts. I think I can use the Chubb system without any major modification. Am I correct ? Thanks.
Old Fat RobertReading his schematic leads me to believe that I need to have common rail wiring within each of the power blocks on my layout.
if this is a transformer type detector like the one below, it requires that only one rail in the block be isolated and that the feed to that rail be looped several times thru the transformer.
It doesn't matter whether the other rail is isolated or not (common).
Thank you Greg. I do appreciate your assistance.