DC loop wiring question

[Wobbleboxer]

I need some help with a DC wiring puzzle that I seem to have created for myself. Not your normal reverse loop question.

My line is basically one big loop, with sidings off, very familiar to most I'm sure. My plan is to extend a new loop off the main one into another area of the garden. The attached picture will hopefully help explain.

Now bear with me cos this is where my brain starts to overheat.

A train running west to east on the mainline will pass through point C and point D, no special wiring there.

Now consider a train entering the new loop from the west via point C. If the centre link is wired to take its power feed from whichever link point B is pointing at, then the train can enter no problem. Further, if the loop is wire to take its power from the centre link, then point A can be set either way and the train will enter the loop.

However, in order for the train to exit the loop point A must be changed and in doing so the polarity will change. But if point B is changed simultaneously it will also change the polarity of the centre link and in theory the correct polarity will remain for the train to continue it's journey and exit back on to the main line via the right hand link. A brief stop in the loop should overcome any jumpy trains caused by the brief power switch, but I was planning a station in the loop anyway.

So long as points A and B are changed as a pair I see no problem here. Or have I got this all wrong?

 

[Gizzy]

I need some help with a DC wiring puzzle that I seem to have created for myself. Not your normal reverse loop question.

My line is basically one big loop, with sidings off, very familiar to most I'm sure. My plan is to extend a new loop off the main one into another area of the garden. The attached picture will hopefully help explain.

Now bear with me cos this is where my brain starts to overheat.

A train running west to east on the mainline will pass through point C and point D, no special wiring there.

Now consider a train entering the new loop from the west via point C. If the centre link is wired to take its power feed from whichever link point B is pointing at, then the train can enter no problem. Further, if the loop is wire to take its power from the centre link, then point A can be set either way and the train will enter the loop.

However, in order for the train to exit the loop point A must be changed and in doing so the polarity will change. But if point B is changed simultaneously it will also change the polarity of the centre link and in theory the correct polarity will remain for the train to continue it's journey and exit back on to the main line via the right hand link. A brief stop in the loop should overcome any jumpy trains caused by the brief power switch, but I was planning a station in the loop anyway.

So long as points A and B are changed as a pair I see no problem here. Or have I got this all wrong?

I believe what you have said is feasible, but you would have to isolate rails as appropriate.

Let me have a look at your diagram and I'll get back to you....

 

[MR SPOCK]

[align=center]If you wired that up everything would heat up in fact , looks about impossible with DC unless you construct some intricate loop detection and logic control switching, or have batteries and radio control,and no track power,

look at the old peco how to wire up a layout booklet should still be for sale, masses of good info there, about two quid I think,

The other way would be to have two parrallel tracks where you have a single link track, it would stop two dead shorts,
[/align]

 

[Tony]

1/ Cant you make the straight bit double track it would be far easyer

2/ Does the mainline run both ways or just one way

3/ Are you using a seperate controler for the extension

Tony

 

[ntpntpntp]

The "tail" of a Y formation normally needs to be treated as a reverse loop, therefore the feed to the "centre link" needs to be switchable between the trackwork in the "left link" and "right link" via double-pole changeover. This should be done via a double pole accessory switch linked to point B. All four rail joints at the frog end of point B need to be insulated.

Then you have tle "loop" which of course needs to be treated as a reverse loop. All four rail joints at the frog end of point A need to be insulated, and the track within the loop wired to the "centre link" via double-pole changeover, again this can be done using a double pole accessoriy switch on point A.

You will have to stop the train and reverse the controller at two places: within the loop when you change point A and switch polarity, and again stop on the "centre link" while you change point B and the polarity of the "centre ink" before you continue out of the Y onto the main line.

Something like that!

The suggestion to make the "centre link" double track and not to bother with points A and B would remove the need for any of this complexity, as in effect the new trackage would just form a "bent" passing loop!

 

[Gizzy]

I need some help with a DC wiring puzzle that I seem to have created for myself. Not your normal reverse loop question.

My line is basically one big loop, with sidings off, very familiar to most I'm sure. My plan is to extend a new loop off the main one into another area of the garden. The attached picture will hopefully help explain.

Now bear with me cos this is where my brain starts to overheat.

A train running west to east on the mainline will pass through point C and point D, no special wiring there.

Now consider a train entering the new loop from the west via point C. If the centre link is wired to take its power feed from whichever link point B is pointing at, then the train can enter no problem. Further, if the loop is wire to take its power from the centre link, then point A can be set either way and the train will enter the loop.

However, in order for the train to exit the loop point A must be changed and in doing so the polarity will change. But if point B is changed simultaneously it will also change the polarity of the centre link and in theory the correct polarity will remain for the train to continue it's journey and exit back on to the main line via the right hand link. A brief stop in the loop should overcome any jumpy trains caused by the brief power switch, but I was planning a station in the loop anyway.

So long as points A and B are changed as a pair I see no problem here. Or have I got this all wrong?

I believe what you have said is feasible, but you would have to isolate rails as appropriate.

Let me have a look at your diagram and I'll get back to you....

Yep, I reckon it's do-able if you isolate both rails at the 4 points in your diagram.

You could use an accessories switch (assuming LGB) with the point motor to set the polarity as required and change the points as a pair by wiring both motors together in parallel.

Have a look at your diagram which I've amended with the wiring and switching.

What I can't work out though, is why you want to do it. Unless you make the 'centre link' long enough for your longest train, you won't be able to reverse a train from either the east or west direction by changing both points together....

 

[ntpntpntp]

Actually, looking at Gizzy's solution I concur: if you're going to switch points A and B simulaneously then it can be done with one double-pole changeover.

The trackwork in the loop must be longer than your longest train of course, and I also agree with Gizzy's note that the "centre link" must also be longer than your longest train if you plan to operate points A and B simultaneously. My previous suggestion with two polarity changes assumed independant changing of the points.

 

[Tony]

Gizzy im sure your solution will work but i have a saying that goes keep it simple, keep it real and although its differcult to know what young Mr Boxer is trying to achive or the space limitations he may have i m sure there must be an easyer solution. i say this as i had a similar track planed but with a few cups of coffee and afew hours staring out the window realised there was a far better way that gave me even more scope for playing and saved on expencive point work and wiring
Tony

 

[Wobbleboxer]

Thanks guys, see I'm not mad, well maybe a bit but no more than anyone else round here.

I had included power breaks in my diagram, but didn't highlight very well, thanks Gizzy.

The track is Peco but I was planning to use LGB point motors and accessory switches. I did originally have the crossing over via a crossing rather than 2 sets of points but I can't get the links from the mainline to come from where I had planned and I didn't like the idea of double track as much of the centre link will be out of view, so I thought I'd add a bit of interest. Also, with appropriate reversing of controller I plan to use it as a reversing loop for turning trains too.

Anyone got any spare Peco points or LGB motors?

 

[Tony]

Colin
just had a quick look thought i had 3 sets of points but can only find 2
Any hoo i have 1 x L/h + 1 X R/h points both used but very good must be worth £40 the pair and also 7 yard lenghts of used but good flexy must be worth £30 the points are large rad and about 2 ft long
this the rail thats thinner than LGB with the wood effect sleepers think its code 250 will take some photos in the morning and post on here tomorow if interested will do free postage if it helps

Tony

 

[Neil Robinson]

Thanks guys, see I'm not mad, well maybe a bit but no more than anyone else round here.
The track is Peco but I was planning to use LGB point motors and accessory switches.

A word of caution.
The microswitches used in the accessory switches are, as the name implies, rather small; they have the relatively high, for their size, maximum current rating of 3A. However many power supplies put out more than that and I've known a fair few failures probably due to accidental shorts. An alternative is to use relays, operated either by track magnets or using the accessory switches to switch the relatively low power relay coils.

 

[korm kormsen]

Colin,

at first thought, you might be better off, if you do not break your power at point B.
it might be easyer, to put two (simultaneous) breaks at points C and D.

or, on second thought, wire everything as a "two reverse loop layout". the main circle being the second loop.
in that case, you would have to break the mainline between C and D.
one switchmotor for points A and B and their polarity together, plus one switch for the piece of mainline between C and D.

give me a couple of months of armchair modelling time - and i will come up with a good solution.
.

 

[beavercreek]

Wow Colin you are in my exact problem territory now. I have posted a thread about how I have been wanting to get a plain and simple method for making a double reverse loop (dumbbell) to replace a point to point shuttle line working with DC analogue. Besides the ideas given about building your own relay boards and using point motors with auxiliary switches (and as Neil says the power could be too much for them if something goes wrong, so more relays), I have found that the only auto method off the shelf is the Massoth auto reverse loop module. This will do what you want and in analogue it just needs the extra small power supply for its own use.
If you are handy with building your own circuits and using electronic components, or know somebody who does,then totally disregard my ramblings as you can make up the required kit for about less than half the cost of a second hand Massoth unit (using the great advice given in this thread and my one) and feel the pride in creating your own stuff.
Me, I can totally rewire a factory, recording studio or house but little circuits and their components seem to perplex me for some reason......don't know why :-