Automatic reverse loops???

[Anonymous]

Hello,

I'm planning a small HOn30 layout and would like it to be loop-to-loop. I want the whole thing to be hands free and have the locomotive go the same route through the loops (the straight path)

I was thinking I could use a photo cell to trigger a tortoise switch machine when the loco enters the loop. I could then use the contacts of the tortoise to swap the polarity of the main track. Since I want the loco to travel the same way each time both switch machines will trigger at the same time.

Also one switch machine will switch the track power and teh other one will switch teh power to the turnout frogs.

The photo cell circuit I was thinking of: http://www.canadiancontent.net/en/jd/go?Url=http://www.mrollins.com/circuit.html

Will this whole idea work? If not what will?

Thanks
Chris
http://www.railimages.com/gallery/chrisschmuck

[Seamonster]

Your idea should work. You'll have to do a bit of experimenting. Here are some things to consider. Whatever you use to detect the train you'll have to make sure it doesn't release and re-trigger between cars. Slanting an IR detector across the track should take care of this. Make sure the detector is far enough into the loop so that it doesn't move the turnout under the tail end of the train. With a Tortoise, you'd need some sort to flip-flop or bistable (latching) switch so that once activated, the power stays on to the switch machine because once the train clears the detector, it will go back to its original state. You'll need to reverse the mainline polarity with each switch machine. It won't be difficult to do. Go for it! Good luck.

[Anonymous]

Thanks for the reply.

The circuit listed in the link uses a relay. So running through a photo cell circuit should throw the tortoise. I'm not sure how to get it to throw the other way when it trips the next photo cell.

The loco will enter the 1st loop, cross the photo cell and through the turnout, witch will switch the polaritly of the main. Now when the loco get to the 2nd loop it will hit another photo cell. This time I need the turnouts to throw the other way.

Any ideas?

Thanks

[Seamonster]

Okay, the relay is your latching switch. It's either energized or not. Send me an e-mail and I'll see if I can cook up a diagram for you.

[Anonymous]

Bob,
I sent you my E-mail.

This is what I want to do.

[FCnota]

Are you using DCC? If you are, why not just use an autoreversing unit (check out Tonys Train XChange)? You'd need two but they are totally automatic. I don't know if they work for DC. Just my 2 cents worth.

[Anonymous]

It will be a DC layout.

I don't have a DCC system and a decoder would never fit in the locomotive.

Thanks

[pcarrell]

You wouldn't have to fit it in a locomotive. An autoreversing decoder is a stationary decoder. It wires directly to your track and you mount it to the benchwork.

I don't know about using it with DC though. Maybe one of the DCC guru's could provide you with some better info?

Heck, I'd be interested in knowing that!

[rrinker]

There is a circuit for this on Rob Paisley's site, but given the complexity of it, you might as well just get the Circuitron AR-1. It's not really that complex in theory - just a set-reset flip flop driving a relay which drives the tortoise. Actually, you could skip the relay, the flip flop has enough output capacity to run a tortoise. Mainline power would come fromthe power supply, to one set of Tortoise contats wired as a revering switch, tot he other Tortoise's contacts also wired as a reversing switch and THEN to the main line in the middle - that way either Tortoise changing position would switch the mainline polarity.
Unless you want to run more than one train, then it gets a bit more complicated.

--Randy