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Post by boxcarwilly on Mar 10, 2017 10:43:26 GMT -5
I have a 10 foot length of track on a new section of my layout that will be used exclusively for passenger service. This piece of track will be isolated at both ends. Question: If track is isolated at both ends, is it possible to power this section from two different power sources using separate connections? One connection to a power source on the main panel 15 feet away, and the other to a power source less then 2 ft. away. I know that in order to avoid short circuits, one power source would have to be off to allow the other to function, but is it possible?
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Post by boxcarwilly on Mar 10, 2017 16:02:28 GMT -5
Let me see if I understand this then. 2 double pole/double throw switches, one side connected to one power source, and the other side to the secondary power source. In the center off position, no power from either source. Switch 1 in the up or down position carries power from the main source. Put this in the off position and put switch 2 in either up or down to carry power from secondary source. Lines come into switches from power sources and then out to the track. Have I got it right?
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Post by Rob Albritton on Mar 10, 2017 23:50:42 GMT -5
Great Drawing. Also, if connecting more than one block of track, keep the polarity the same - like this:
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Post by boxcarwilly on Mar 11, 2017 9:51:12 GMT -5
I am not using DCC so 1 and 4 would be to the main DC source and 3 and 6 to the secondary source. The problem being 2 and 5. Do I have to run two separate leads to the track or just one? I guess you could think of this section of track as a block unto itself.
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Post by zoinks007 on Mar 12, 2017 17:17:04 GMT -5
2 and 5 are the "common" leads, so they are the leads powered by the supply currently active based on switch position. Those are the leads that will actually go to your track... (This is at least typical of most DPDT switches.) DC or DCC matters not.
If in doubt, a cheap ohm meter is your best friend. Place one probe on the center "common" pin and one on the pin to either side (long-ways, or in other words the three pins in a line). You should get infinite resistance when the switch is off or away from that pin, and no resistance (or very, very little) when the pin and switch are aligned.
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Post by boxcarwilly on Mar 13, 2017 12:56:50 GMT -5
OK, in reading the responses, I'm beginning to think I made a mistake in asking. The track in question will be a block unto itself which will be isolated at both ends. Now the plan was to run two power leads to this block from two different power sources from two different places on the layout. I understand that I can't have power from both sources to the block at the same time. They short each other out, hence the switch to shut power off from one source, and all the second source to run the block. I envisioned two switches, in two locations and when I want to power the block in question from one location, I turn the one switch off. When I want to change locations, I just alternate between the two switches which are on two separate control panels as long as one of them is in the off position so as not to create a short. Power sources would be identical. This is giving me a headache.
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Post by boxcarwilly on Mar 13, 2017 12:59:11 GMT -5
Here is another way to look at this. Picture a length of isolated track. The track on both sides of this block are controlled by one central power source. It's the block between the outside tracks that are controlled by both power sources. This is the block that I need to alternate power sources on, the outside tracks fore and after remain the same.
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Post by emaley on Mar 13, 2017 15:47:07 GMT -5
I have read this several times and it sounds like you want to control the train from either of two different locations. A dpdt switch will do the job. A short would be the result of not maintaining correct polarity if a switch was not used. Just wire middle terminals to the track and either end terminals to the separate power supplies. Not sure what the purpose is, but I am sure there is an easier way.
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Post by boxcarwilly on Mar 14, 2017 11:52:59 GMT -5
Thanks again for the suggestions. And I now have an idea of what to do but do I need two separate DTDP switches or just one in a central location? As I said in the beginning of this thread, This particular piece of track will be exclusively for a passenger train, however, it needs to be controlled by two separate power source. The main source is will be on a panel 15 feet away from this track but still visible. Now here's the other side of it. There will also be a power source on the layout less then 2 feet away from this section of track. I'm doing this so that two operators will be able to control this passenger train but only in this block. Just to make it more clear, in the same location will be a functioning yard which will be controlled exclusively by the second operator and power source, so the passenger track will need to be controlled by the second operator for the purposes of building a consist, changing engines and other purposes, and the main operator on the main panel won't be able to do that. Now if there is no need to disturb the passenger train, then it becomes a through track, after stopping at the station, and will be controlled from the main power source while the second controller will just look after the yard and feeder tracks. This is why the two separate power sources. I guess without actually seeing it, it's hard to visualize. I understand about the DPDT switch but the question now is, where to put it? At which location?
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Post by boxcarwilly on Mar 15, 2017 11:07:49 GMT -5
Thanks Greg.
Yes to first question. No to DCC. Too late, too costly. I think I have a handle on what I need to do and how I want to accomplish it. Not quite there yet, but will be by the summer. Then we'll see.
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Post by zoinks007 on Mar 15, 2017 14:58:26 GMT -5
Thanks again for the suggestions. And I now have an idea of what to do but do I need two separate DTDP switches or just one in a central location? .... I understand about the DPDT switch but the question now is, where to put it? At which location? With the hope I'm not being "too helpful" (I'm often "too helpful" without meaning to be).
There would necessarily be only a single DPDT switch, and if I had to choose between one of two locations, I'd choose the more heavily used station. It's a mechanical device, of course, and the nature of the DPDT design means there can be only one.
However, if you're interested in being a little innovative, the relay idea is actually a fantastic option and, frankly, conceptually not that different from how you power a turnout frog. The device here would probably do the trick:
www.ebay.com/itm/12V-1-Channel-Relay-Module-Optocoupler-Low-Level-Trigger-Expansion-Board-Arduino-/112053316365?hash=item1a16e5eb0d:g:7AEAAOSw7s5Xgzcv
The shipping is free, and depending on where you buy the DPDT switch, it's not much more expensive if at all. Hard to beat a buck. But this way you separate the control of the power from the power itself, whereas with the DPDT switch you have the one physical device and it directly controls power polarity. To control the relay, you'd just need switches at each station to trip it, and those you probably already have (same as for throwing turnouts).
The negatives would be common, which admittedly can theoretically cause issue (shouldn't since both units are tied to the same ground in your house), so you'd route the positive through the relay. It's been a long, long time since I did any hands-on electronics, which I'm really looking forward to digging into. But this seems to be at least a viable approach. Good news is it's DC, so a simple volt meter would tell you if it's working correctly.
Please forgive me if I served to beat that old dead horse...
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Post by dawdawes on Mar 15, 2017 20:33:23 GMT -5
we did this a lot in the UK before dcc and I will be doing it for my new z layout as its dc. one dpdt switch per section, both controller go into one switch, one top, one bottom, with one out to the track.it's the only safe way to do it, never put 2 controllers on the same track without a dpdt switch dawdawes.com
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Post by boxcarwilly on Mar 17, 2017 13:13:01 GMT -5
You don't need to get hostile. I've already decided that the switch I need will be located on the main control panel 15 feet away from the actual track in question. The second operator sitting next to the station will have no ability to control the passenger track. He will have total control over the yard instead which will be beside the station. Also, I have learned the hard way that buying anything from China on Ebay is risky to say the least especially when it comes to electronics of any kind. I've bought lights, from 3 different sellers on Ebay to use with my layout and out of each lot I've bought, half didn't work. So I don't buy them any more. I get my street lights and such elsewhere.
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Post by boxcarwilly on Mar 18, 2017 10:54:10 GMT -5
Link took me to an Ebay listing. Shipper is in Hong Kong. You may be in Colorado, but the item is manufactured in China. No thanks.
I've decided what to do as indicated.
Thanks for you help everyone.
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Post by boxcarwilly on Mar 19, 2017 10:29:44 GMT -5
Sorry Greg; The link in question was supplied by zoinks 007. But it's all academic as I've decided to power the track from one source only so a second operator will not be able to but still have full control over the yard.
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