I use DCC on a medium size HO layout. No wiring issues. Reading some "dead rail" articles (locos run on batteries) and wonder if this would work:
DCC power feed to track is easy, 2 rails with 2 bus wires underneath with feeders. The problem is turnouts (omit reversing loops for sake of discussion). Could all turnouts be unpowered or dead if every loco had "stay alive" type capacitors? Some say 6 -20 seconds of power. I think 20 sec would work - my locos don't stay on top of turnouts that long.
Are there more expensive capacitors available to assure 20 seconds for all locos & decoders? I realize some DCC functions would not work while on top of dead turnouts, but to me this is a great wiring simplification idea.
Terry
chances are that you don't need any additional run time in you locos... a dead frog is not very wide, and most locos span the dead area without additional help , very short [like short geared steam] may not ... depends on the number of your turnout also, smaller number have shorter dead areas
If you find some, let me know. I run DC and I want to keep the lights on in my subway cars while they stop at the stations. I'd need about 40 seconds of power back up. Proble is the run time between stations can be less that 20 seconds.
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
Unless your turnouts are electrically isolated from your mainline track, wouldn't they receive power (minus the frog) from the connection to your mainline? Or, are you strictly talking about the frog?
Tom
https://tstage9.wixsite.com/nyc-modeling
Time...It marches on...without ever turning around to see if anyone is even keeping in step.
TBat55 I use DCC on a medium size HO layout. No wiring issues. Reading some "dead rail" articles (locos run on batteries) and wonder if this would work: DCC power feed to track is easy, 2 rails with 2 bus wires underneath with feeders. The problem is turnouts (omit reversing loops for sake of discussion). Could all turnouts be unpowered or dead if every loco had "stay alive" type capacitors? Some say 6 -20 seconds of power. I think 20 sec would work - my locos don't stay on top of turnouts that long. Are there more expensive capacitors available to assure 20 seconds for all locos & decoders? I realize some DCC functions would not work while on top of dead turnouts, but to me this is a great wiring simplification idea.
Are we just talking about the frogs? What brand of turnouts? Many people leave their frogs unpowered with no problems.
Sheldon
I was thinking isolate the entire turnout, not just the frog. LIONs lighted passenger cars make me think again because they can sit on turnouts longer like double slips. Then again, they are big enough for lots of capacitors inside.
Thank you for your replies.
the PSR has 3' stopping sections which locos with 3-4 0.5-1F 5V keep alives can ride thru.
how do you make sure you'll never stop on an unpowered turnout.
greg - Philadelphia & Reading / Reading
LION brought up one of the issues l have with my subway display the cars go dark every time they stop ( I run them on Bachmann reversing track) in my case I may just put in battery lights but for a large display you would need stay alive caps.
Joe Staten Island West
TBat55I was thinking isolate the entire turnout, not just the frog.
Well you are thinking outside the box.
The problem, as I understand it, is the difficulty attaching feeders to turnouts. You will find that soldering keep alives to little bitty soldering pads on the decoder at least as challenging. When you do, you have a decoder that will be hard to program.
https://sites.google.com/site/markgurries/home/decoders/keep-alive-compatibility
Henry
COB Potomac & Northern
Shenandoah Valley
I've never powered my Atlas #4 or #6 turnout frogs. The rest of the rails get power, there is no point to insulating them, that serves no purpose. So the only unpowered section is the frog. My smallest loco that I've run on a layout is a Bachmann GE 44 tonner, and it has no stay alive capacitor in it. Never had a problem, even at slow speed. Anything bigger - if it has all wheel pickup, and stalls on a frog - you have other issues.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Yes, I agree, No point in insulating newer "DCC friendly" turnouts. Just seems to me turnout polarity issues turn off some people and the whole thing can be ignored with stay alive caps and not powering any TOs.
Randy, you have always given excellent electircal knowledge. Are there "super caps" or something that lasts longer (but costs more) than s. a. caps?
TBat55No point in insulating newer "DCC friendly" turnouts. Just seems to me turnout polarity issues turn off some people and the whole thing can be ignored with stay alive caps and not powering any TOs.
Retrofitting stay-alive caps is much more difficult than wiring turnouts. Totally dead turnouts with standard DCC is not a viable idea. Full stop.
Layout Design GalleryLayout Design Special Interest Group
TBat55 Yes, I agree, No point in insulating newer "DCC friendly" turnouts. Just seems to me turnout polarity issues turn off some people and the whole thing can be ignored with stay alive caps and not powering any TOs. Randy, you have always given excellent electircal knowledge. Are there "super caps" or something that lasts longer (but costs more) than s. a. caps?
"Super caps" are just higher value - it's newer technology than typical capacitors where 1000 microfarads might be a large value (it's just .001 Farad - the Farad is a large unit). Supercaps are 1 Farad, or even more. A 1 Farad capacitor stores 1000x the energy of a 1000 microfarad capacitor (.001 Farad).
Downside is they are typically rated for no more than 5 volts. That's too low for DCC track voltage. So you ahve to put multiple capacitors in series, which increases the voltage ratign but decreases the capacitance rating. Say for reasonableness you put 4x 5V 1F supercapacitors in series, to make a 20V capacitor, it would be .25F But that's still 250 times a 1000 microfarad 20V capacitor - and putting 4 of those older style capacitors in parallel to increase the capacitance would still only result in a total of .004 F.
So the main advantage is that they have a MUCH MUCH higher capacity per unit volume than previosu capacitor technology. And to be able to keep the motor turnign that's drawing half an amp pulling a train, you need to store a lot of energy if you want it to run for more than a fraction of a second. That's what supercapactprs get us.
It's possible, for example, to replace your car battery with a bank of supercapacitors. They have plenty of power to crank over the engine, and the bank of capacitors would weigh significantly less than a traditional lead-acid car battery. However, leave your lights on even a short time and you might not be able to start the engine. The total energy storage of even the supercapacitors is still less than that of the battery.
Got it. Thanks for all who replied. It's a dead stop.