12v Turning Loop Tech Talk

[Shazam12]

Hi Andromeda,

Can you help me out on another electronics subject? No option to send a PM on this board, so I'm hijacking this thread here :-).

Was trying to get a turning loop into action for the 12v track. I've found a nice schematic on this site:

http://www.nproject.org/nl/algemene-tips/automatische-keerlus-met-een-relais-weerstand-en-twee-reedcontacten-voor-analoog-2-rail-systeem.html

I'm not too good at electronics, could you spell out for me what components to use and how to hook them up? This is a nice automated setup where the trains can keep running instead of stopping and do a pole reversal.

[bricks n bolts]

I'm not too good at electronics, could you spell out for me what components to use and how to hook them up? This is a nice automated setup where the trains can keep running instead of stopping and do a pole reversal.

I haven't used it but you could try this : http://www.azatrax.com/automatic-reverse-loop.html

Site's components looks very good for 12v, I'm tempted to give their sensors a go.

[alainneke]

I haven't used it but you could try this : http://www.azatrax.com/automatic-reverse-loop.html

Site's components looks very good for 12v, I'm tempted to give their sensors a go.

Looks good! If you don't mind soldering, here's one that you can build yourself. I currently use one to reverse polarity in my wye, and it works great

[bricks n bolts]

I currently use one to reverse polarity in my wye, and it works great

Cool, can we have a picture of how you've mounted and hidden the sensors?

[alainneke]

Cool, can we have a picture of how you've mounted and hidden the sensors?

Sure, here you go...

The sensor and infrared LED (no grass yet..)

Infrared sensor by alainneke, on Flickr

The power supply mounted under the table (input 15V AC, output 12V DC)

Infrared sensor power supply by alainneke, on Flickr

An overview of the wye (after letting the grass grow). The sensor is hidden under a little structure, the LED is mounted in the signal post

Wye overview by alainneke, on Flickr

... and how it works:

- the polarity on the left side of the wye (the tracks leading to the engine shed) matches that of the sensorless branch, so a train can pass the isolation without problems

- when passing the sensor, the polarity on the left side of the wye is reversed to match the polarity of the sensor branch*. When the train has passed, the polarity switches back

*This particular setup only works with DCC, because the motors don't reverse direction when you change polarity (forward is always forward). Analog layouts require 2 sensors and an additional piece of isolated track. Furthermore, you should only change the polarity of track sections ahead of the train (not under the train) when running analog

Edited February 22, 2013 by alainneke

[bricks n bolts]

Sure, here you go...

That's great alainneke, masterly done with the dual purpose signal post. Great layout too, with 7740, Horizon Express, monorail, train shed and crossing!

Like the grass too, helps finish it all off, my layout is currently on two dining tables, so don't think I'll be allowed to drill through them , but the grass idea may help hide all the wiring.

[alainneke]

That's great alainneke, masterly done with the dual purpose signal post. Great layout too, with 7740, Horizon Express, monorail, train shed and crossing!

Like the grass too, helps finish it all off, my layout is currently on two dining tables, so don't think I'll be allowed to drill through them , but the grass idea may help hide all the wiring.

Thanks! The other half of the layout is just as interesting, but I haven't got around to making decent pictures yet. The grass can be bought at most garden shops and is great to work with; just be sure you get the most compact (shortest) grass one you can find

[Shadows]

By your own admission, this was a hijack of the other topic and really needs it's own place so neither topic gets lost, so I've split the two.

Carry on.

[Andromeda]

Wicked and really informative tech Guys... Which is why I asked for, and wanted this to have it's own life... ! Thanks Shadows.

@Shazam

I think you only need 10 posts(don't quote me) to PM. The repies by B n B and Alainneke are both worth following up on. Your original link won't work straight off the bat as it uses two independant solenoids to switch the points from the same polarity supply, where as the ogeL point switch uses reverse polarity.

@ Bricks n Bolts, Alainneke

I did follow up on your suggestions as I have come across the polarity headache before, and have found a wealth of knowledge, thanks. How to adapt this for the old 12V, I imagine modified power rails or the rarer signal rails...

[bricks n bolts]

@ Bricks n Bolts, Alainneke

I did follow up on your suggestions as I have come across the polarity headache before, and have found a wealth of knowledge, thanks. How to adapt this for the old 12V, I imagine modified power rails or the rarer signal rails...

You'd have to modify them or just break the electrical connection with some sticky plastic at a join, the signal rails only isolate the power on one side at a time as they are for turning on/off the power rather than reversing the polarity.

[bricks n bolts]

I haven't got around to making decent pictures yet.

You're not kidding! Just seen your new photos on Flickr, love the town, airport, carousel and monorail, nice use of space and function, but this is simply amazing :

[alainneke]

You're not kidding! Just seen your new photos on Flickr, love the town, airport, carousel and monorail, nice use of space and function, but this is simply amazing :

Thanks :) It's quite hard to get everything to fit, especially the monorail. The command station is a great piece of equipment with a lot of possibilities!