What Switch ?

Not an expert here so need some advice.
I want to isolate both sides of a piece of track - but rather than use two SPST (one for each rail) I'd like to use the one switch. Why ? I have a
freight yard which I want to totally isolate from the main line so I can operate the yard independantly of the main line. Main line is an oval.
What sort of switch do I need - (rocker style preferred).
Cheers Mal Oz
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SPST means Single Pole Single Throw, ie it will switch a single circuit on or off.
You wish to switch 2 circuits, so you need a DPST or Double Pole Single Throw.
A DPDT Double Pole Double Throw (or DPCO double pole change over) will also work. The double throw means that it has 'On' positions, otherwise known as a change over switch. Just leave one on the sides unconnected.
Regards Jeff
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So, Pole = Circuit ! Now it makes sense.
Brilliant Jeff, thanks.
Off to Dickies I go then.
Cheers Mal Oz

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More or less; more accurately think of it as the 'moving' part of the switch That makes the contact.
So a Single Pole Single Throw has a moving part (pole) that can only move (connect) to one place.
A Double Throw has a pole that can move to one of 2 places.
So a DPST has 2 poles that each can move to 2 places
Trying a bit of ASCII Art:
\ -------0 0------ SPST
-------0\ \ 0----- SPDT -------0
\ -------0 0------ \ SPDT -------0 0------
-------0\ \ 0----- -------0 -------0\ DPDT \ 0----- -------0
Regards Jeff

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Draconus wrote:

Try for a DPDT center off. That way the yard can be on its own circuit, or connected to the main, or completely unpowered.
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It's turtles, all the way down

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If you use a DPDT which has a centre OFF position (two position switches exist also) you can wire two controllers so that the yard could work independently. The centre terminals feeding the yard. These are very useful when constructing a change over section from one contrller to another. I employ this mode in stations where I can either leave a train isolated or control it as I wish.
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Draconus wrote:

From the DSE catalog with your criteria.
P7720 P7708 P7730
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Regards

Kevin Martin
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Thats handy, thanks.
I like the DPDT idea, now that i know what i'm doing (well, more than i did yesterday anyway !)
cheers mal oz

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Assuming you have two controllers get a DPDT switch as suggested, however make sure that is "centre off", that way properly wired you'll be able to run your yard from either controller or have it entirely insulated. I have all the major "operating areas" of my layout wired that way, the main line, the yard and the shed ... I can use either controller (say) to drive from the main in to the yard, flick a switch or two and get another train running on the main using the orginal controller and then when that's up and running around in circles use the second controller to shunt the yard. The operation is prety seamless in practice and dead easy to wire.
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All the best,

Chris Wilson
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Thanks, I assume then you only need to cut the one rail running into the yard ?

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If you're using common return wiring then yes (one transformer per controller, all 'returns' wired togther - doesn't work if you have more than one controller wired to the same transformer), otherwise no, cut both
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All the best,

Chris Wilson
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yeah I have the two controllers wired to the same transformer....
... just searching the net now for a diagram for all this, not having much luck at the moment.
..so I need to cut both then by the sounds of it.
Cheers Mal Oz

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I found the 'Wiring The Layout' pages 2 and 3 on this group's website - it shows the circuit using 2 DPDT's and assumes Electrofrog points.
Can I use the same circuit layout for Insulfrog ?
Cheers Mal Oz

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