Yea, it will short with reverse polarity depending on what you are running, but I don't see a kaboom. DC is more forgiving of these things than DCC.
rrinkerThough what all this has to do about insulating a turnout.... --Randy
You would have to dig deep into the posts......but it's in there!......LOL
Take Care!
Frank
I've been away for work (still am) but the only way you get the 24 volts is if there is a common rail reference - if the top rail was connected with no insulating gap, then across the gap you would indeed get 24 volts if one pack was full throttle forward and the other full throttle reverse.
OR is yo used a dual pack that wa snot made for common rail wiring - back in teh day when they were transformers, rectifiers, and a rheostat, there were usually two kinds of multi-control power packs. One kind, the cheaper ones, had one trnasformer, one rectifier, and two rhostats (and direction switches of course). Those were no good for certain types of wiring because they already had common connections on the DC die through the single rectifier. The netter ones actually had 2 trnasformers adn 2 rectifiers int he case - truly liek 2 completely independent power packs.
Same thing could happen if you used something like the small handheld cab controls, but ran them all off a single DC power supply.
But - 2 packs, common rail - layouts were built for YEARS without frying locos crossing the gap - you'd never get far enough to have the leads truck in one block and the rear truck in another, you'd get a short as soon as the second wheel of the first truck crossed the gap and with any luck the circuit breaker in the power pack would trip before the truck sideframe melted - remember those old spring bent pieces of metal type breakers, when they tripped that piece of metal, that you had to push back on to the main bar, was HOT. VERY hot. ANyway, two independent power packs, common rail wiring - that's only every Atlas track plan book ever. It works.
Though what all this has to do about insulating a turnout....
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
You could save yourself a whole lot of time and trouble by going DCC. And it is not all that expensive. What more can I say?
Rich
Alton Junction
There is alot more to my layout than simple ovals. That was just the simplist way to describe the general layout. As for the Block system I am going to have to have someone who is experienced with "Blocks" show me, because I have read more than a few sources on "Blocks" and frankly I don't get it! I am trying to get the most out of what I have for the least expenditure. With two power supplys and two track routes that are concentric and isolated from the other two track routes I can run two trains running in opposite directions. If I have four power supplys and each of the four track routes has it's own power supply, and all are isolated from each other at the turnouts, I could run four trains all running in the same direction or alternate the directions. Sounds like a great deal of action and possibilities. All will go fine as long as I keep the polarity the same/same between two track routes and virtually the same/same speed when I move a train from one line to the next. Not really that complicated.
to the MR Forums!
Personally, I think that you'll get tired of running locomotives around ovals, one or even four of them, pretty quickly, and decide to go for a different track arrangement. While you could divide the layout into multiple blocks, if you're going to be the sole operator, I don't see any need for that. My DC-powered layout, partially double-decked, fills the room, and while I have many tracks which can be killed or energised as needed, only one train can run at a time, because there's only one operator, even if that train is using three or four locomotives.
Wayne
I run three cab, block control, with Crest wireless throttles,
Frequently some one will try to enter a block not turned to his cab. One of three things happen:
i) next block same polarity, different throttle, train is being controlled by other throttle.
2) next block is off, the train stops, until block switch is changed.
3) Reversed polarity the engine osoclates about 1/2 inch until block switch is changed.
No smoke, damage, etc in 16 years.
Dave
Watchman54 Thank you Frank. Very helpful. At least I know I am not completely crazy. Maybe one day I will spring for DCC and all ths will be mute but for now DC is good for me. Besides I have to sneek up on those kind of expenditures or my wife of 45 years will not be happy. She has already threatened to take my ebay privilages away.
Thank you Frank. Very helpful. At least I know I am not completely crazy. Maybe one day I will spring for DCC and all ths will be mute but for now DC is good for me. Besides I have to sneek up on those kind of expenditures or my wife of 45 years will not be happy. She has already threatened to take my ebay privilages away.
Would love to go all DCC but the added cost is prohibitive for now. I will switch over to DCC when my wife is fully onboard with model railroading. I would have prefered HO or O rather than N but space is a concern and I want more than what I had in the past with HO. My current layout is based on the old west and the locos are a little small for DCC.
RR_MelEven at half throttle I would never connect two power packs together with reversed voltage, not much difference than putting a couple of AA batteries shorting together as far as I’m concerned.
Mel,
I believe You are missing the point......No one said that they are connecting two separate power packs together with opposite polarity. The point being, is to make sure that they ARE NOT of opposite polarity, when crossing into one another regardless of voltage setting........
To put it plain and simple.......On a DC layout the engine is controlled by the Variable DC output to the track, which is from 0 to around 13volts DC. There is no constant 12volts to the track, unless You turn the throttle all the way up, You would have to do that to both throttles to even get close to 24volts.
In DCC the voltage is constant to the tracks roughly 13.5 + The decoder in the engine controls the speed/start/stop/lights etc. In that scenario if you had two different power districts set-up and one was a different polarity than the other, when engine crossed into the gapped power districts, you then would have a problem, in which case the DCC base should shut down.
Bye, Bye........
Watchman54 I thought I was asking a fairly simple question, obviously I was not. If I want to run two trains, both going counterclock wise, and changing occasionally to a longer line, on a DC only setup, with only one train on a particular line, it seems isolation of each concentric route, and each with it's own power pack is the easiest way to set things up. I understand that the polarity must be cosistent between controllers and the speeds should be as close as possible for the switch from one track route to the next. Frankly I do not see a problem with this method of operation. Setup this way I should be able to run two trains in opposite directions with one train running only on the two outer track lines and another running only on the inner two tracks. Maybe one day down the line I will understand the finer points (i.e. Blocks) that you guys are worried about but for now I am going to try and keep it simple and pay attention to what I am doing so as to not smoke my loco's.
I thought I was asking a fairly simple question, obviously I was not. If I want to run two trains, both going counterclock wise, and changing occasionally to a longer line, on a DC only setup, with only one train on a particular line, it seems isolation of each concentric route, and each with it's own power pack is the easiest way to set things up. I understand that the polarity must be cosistent between controllers and the speeds should be as close as possible for the switch from one track route to the next. Frankly I do not see a problem with this method of operation. Setup this way I should be able to run two trains in opposite directions with one train running only on the two outer track lines and another running only on the inner two tracks. Maybe one day down the line I will understand the finer points (i.e. Blocks) that you guys are worried about but for now I am going to try and keep it simple and pay attention to what I am doing so as to not smoke my loco's.
As long as You keep the polaritys the same when crossing into another power packs territory, You will not have any problem's. I've been doing it for yrs. You won't have 24 volts in the transition......maybe 12volts......unless You have both power packs set at Full throttle, in which case, it would probably be more than 24v, some packs put out more than 12 volts at full throttle. My current layout is DC 3-CAB block control, with 3 MRC CM20's, now that is enough power to smoke a boxcar.......have not had any problem's, other than My crossing a feeder, in which case the power source shut down. Layout has been up and running since 1980. I have since downsized it to a 2-cab system. The layout was just too big for one person, but I had built it in sections so I was able to shorten it and gave the sections to My Grandson's for their basement layout still in construction. It was 12 1/2 x 40' x 12 1/2' in My attic.......now it is roughly half that size. It is two rail insulated, with block control. I do run DCC on it once in awhile......no big deal....it works for My needs.........
This pic' (1959) is in My Parents basement when I was 17yrs. old, that is the last time I used common rail wiring, one rail insulated: I powered that with a MRC Golden Tri-Pack, that was 3 separate power packs in one case.......still have it. Track was Atlas brass hand laid code 100.
I get your illustration, and if the power packs were connected opposite the way you have, yes, KABOOM
Both power packs have to have the polarity the same.
The OP will have to make sure, by testing a loco on each track, and make sure the power packs all go the same direction, and the loco moves in the same direction on all three loops.
Mike.
My You Tube
I didn't envision a 24 volt short either.
Henry
COB Potomac & Northern
Shenandoah Valley
I'm not questioning Mel's eclectrical knowledge, but this doesn't seem any different to me, that a train moving from one block to another.
Thank you Frank for your help. I will read the information you referenced.
So if I isolate the track (on both rails) at all turnout intersections by using plastic connectors, and make certain the speed and polarity is the same for all four track routes, then there should be no issues as the locomotive passes over the junction of the two turnouts? Is there any chance that the locomotive would recieve 24 volts as it crosses the gap between the two track routes due to the two seperate power supplys?