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REVERSING LOOPS
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 Posted: Wed Mar 14th, 2012 06:20 am
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aethereus
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I had a crazy thought and wonder if anyone has tried this. While dreaming about a Birdwater and Raspberry cartoon of a GG 1 for my G scale layout, It occurred to me that maybe here was a solution to the age old issue of reversing loops. What would happen if I separated all of the wheel pickups for the motors and wired each pair through a bridge rectifier and then to the motors. This would mean that I would only need to make a pair of rail cuts just before the train reentered the main line. There would be no need for additional block cuts nor any block wiring. In addition there would be no need for a DPDT switch which would need to be manually thrown nor train position detectors and relays for automatic operation. The flaw is that you couldn't reverse direction with the cab control. HOWEVER, if a fella were to rip the RC receiver out of an old Radio Shack toy car and couple it to a latching relay, then reversing would be through the transmitter. A switch could be added to a wheel set before the bridge to couple the relay to track polarity for reversing if the reversing loops were not being used.

Whaddya think? Has any one tried this? Would love some comments.

Duncan

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 Posted: Wed Mar 14th, 2012 01:41 pm
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Herb Kephart
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If you spend a couple more bucks on a Shack car with a radio with a proportional throttle, and a battery (NimH or LiPo) all of the above becomes moot---



Herb 


I'm an avid commics fan, but Birdwater and  Raspberry is a new one to me.



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 Posted: Wed Mar 14th, 2012 02:34 pm
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W C Greene
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I say build it and see if it works. If it doesn't, then find another way. It might take far less time building the prototype than waiting for suggestions from the great unwashed. Please let us know how it turns out.

And have fun, run a train today... Woodie



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 Posted: Wed Mar 14th, 2012 05:15 pm
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aethereus
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Herb--Birdwater and Rasbery RR by Bruce Bates is one of my heros.

http://bates-r-us.org/birdwater/


Check out his 0-2-0 Locomotive among other stuff. Besides his drawings that regularly used to appear in Garden Railroad are a number of cool items that he has actually built, He uses figures in very imaginative ways to boot. Not everyones cup 'o tea, but he can definitely stir peoples creative juices.

Duncan

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 Posted: Thu Mar 15th, 2012 04:41 am
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Herb Kephart
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I think that that is one great link!

Who else has enough imagination to come up with an asparagus car?



Herb 



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 Posted: Fri Mar 16th, 2012 11:55 pm
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Si.
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Hi Duncan

Thanks for the 'Birdwater & Raspberry' link !!!
I loved Bruce's drawings when I used to get the mag.

I belonged to a club then, and always showed them to other members...
...they took the 'Birdwater' out of me though !

I think they're great, and would run a 0-2-0 on my line any day !

ELECY STUFF...

Duncan, since you want your train to run all day & G-Scale motors can use up quite a lot of juice ( not raspberry juice ); it seems to me that nice as RC may be, it just won't do it without a zillion batterys.

Even if you run on AC with a rectifier in the train, you will still get a short, with only 1 track isolation break.
Since the train wheels will bridge the two sections.
AC or DC, you still need a whole isolated section.
Also as you point out, no remote reverse with AC either.

These isolated sections should be at both switch/turnout exit points, so the electrical loop section is as long as possible.
You may want to run other 'lecy cars' also, such as lighted passenger cars.

I see now you want 'automation' and auto polarity changing.
You will need 2 spring loaded turnouts.
The polarity of each ends loop remains constant...
...and the connecting lines polarity is auto reversed.

You could do this with a latching-relay & track-mounted reed-switches; with a simple magnet under the loco.
Slot-car magnets are very strong, small & cheap.
I can't see there is a simpler way.
You do need wires to the 3 sections though.
Can't realy be avoided.

Cheers

Si.



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http://www.freerails.com/view_topic.php?id=7318&forum_id=17&page=1

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http://www.slotforum.com/forums/index.php?showtopic=59295&st=0&a
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 Posted: Sat Mar 17th, 2012 12:59 am
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Herb Kephart
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Si-

If I understand correctly---and that, some will say is a first--Duncan is proposing every axle with metal wheels is to be a separate pickup, which would have a diode in it's lead to the motor--so any circuit from one axle to the next would be blocked by the diodes.

But still reversing is a problem-


Herb



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 Posted: Sat Mar 17th, 2012 12:50 pm
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Si.
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Hi Herb & Duncan

Duncan's idea is an interesting thought, I have not come across before.

The problem is; as the wheels cross the insulated joiner, there would almost certainly be a short-circuit, even if just for a moment.
This would probably be enough to trip the circuit-breaker on most power-packs.

There is a real-small following for slot-cars running on AC power out there.
If you Google 'AC2 slot-cars' you will find their concepts on the AC2 site.
This isn't really relevant to trains in particular...
...but they use AC power to defeat 'DC engine braking'...
...& using diodes reversed for each of 2 throttles, & can then run TWO cars independently, in ONE slot.
Slot-cars obviously only go forwards though.
( clever huh, no DCC stuff either; a kind of 'Analog DCC' ! ).

Anyhow...
...personaly I would want a solution that just allows any loco to be put on the track & run without any mods ( except for a small magnet fixed underneath, which is easy ).

Just a thought on the wiring.
I do a lot of sound-recording wiring; and require neat, durable & easy to break-down / set-up installations.

If your power-pack was near one of the loops, you would only need 2 short ( neat ) cables at this point.
Perhaps only 1 in fact if you were smart how you wired it up.
For the cable to the distant-loop; I would use good quality, thin & very flexible 'microphone-cable'.
This is available as 2 or 4 core, both with an earth braid.
You could with a suitable mini-connector, fixed almost invisibly to a tie at the loop; connect your track-power & reed-switch, with 1 cable, straight to the latching-relay ( which would be in a small placky-box ), next to the power-pack.
It would help if your power-pack had a straight 'un-controlled 12v DC out, for the relay-coil.

Only 1 long cable, which is thin, flexible & doesn't mind getting stepped on, coiled up or generally abused ( reliable ).

Suitable mini-connectors ( PC, RC, audio, etc. ), would make this easy to connect-up & break-down, change, fiddle with etc.

For 'Auto' operation, you would need 'spring-loaded' switches / turnouts; and the train would travel the loop in 1 direction only.
Which shouldn't be a problem ( ? ).
You could wire in a manual DPDT swith as well; but I'm not sure you'd need / want to, with such a simple track-plan.

Hope that makes sense & is some help.

Cheers

Si.



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' Mysterious Moose Mountain ' - 1:35n2 - pt.II
http://www.freerails.com/view_topic.php?id=7318&forum_id=17&page=1

' M:R:W Motor Speedway !!! ' - 1:32 Slotcar Racing Layout
http://www.slotforum.com/forums/index.php?showtopic=59295&st=0&a
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 Posted: Sat Mar 17th, 2012 03:20 pm
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Herb Kephart
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Si

If the gap that you are concerned with momentary shorting was actually two gaps, about 1/4" (6.35mm for those that have callously abandoned Imperial [you know who you are!]) and the short rail is electrically dead==no short.

There are folks that run trolley (tram) systems with diodes, and half wave DC over here. Similar to the slot car system that you describe, two operators can run separate cars on the same track, with individual control.

I agree that a lot more use should be made of the excellent mini-connectors that are available now--I think of this every time that I start cutting wires to remove something. Problem is that that is the ONLY time I seem to think of them, and never get around to ordering any. Also, the smallest--the ones that come with leads attached- are almost impossible to solder new leads into.


Herb 



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 Posted: Sat Mar 17th, 2012 07:16 pm
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Si.
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Hi Herb.

Yeah...I was going to mention a 'dead-strip'.
Slot-car folk use short 'dead-strips' to trigger timing-gear.
You could actualy trigger a latching-relay using a 'dead-strip' as well.
The motor continuity provides the 'contact' instead of a reed-switch.
Could be a problem with multi-pickup wheels, as opposed to short slot-car braids.

There are about a zillion different types of micro-connectors available.
The ones for RC and the like, from hobby-stores are way over-priced IMO.
Electronics suppliers sell a much larger range, way cheaper.

Yeah...a lot are VERY small ( micro, in fact ).
0.1" pitch is common, and small.
0.2" pitch are still small for models; but are normaly that much easier to work with.
Some brands have crimp-inserts as pins; and are much easier to assemble.

PC fan-connectors aren't too bad, as it happens.
For inside of locos etc.
Also they come as ready made extenders and stuff; and can be cut and hacked with the plugs / skts. already fitted.
Very cheap as well.
Especialy if you find a PC in the trash.

Cheers

Si.

P.S.
The other thing about microphone-cable Duncan...
...is it comes in lots of different colours.
eg. Black, Grey, Green, Blue, Red, etc. etc.
Could be good for 'camoflage' on carpet etc.
The grey stuff gets used in old stone buildings a lot.



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' Mysterious Moose Mountain ' - 1:35n2 - pt.II
http://www.freerails.com/view_topic.php?id=7318&forum_id=17&page=1

' M:R:W Motor Speedway !!! ' - 1:32 Slotcar Racing Layout
http://www.slotforum.com/forums/index.php?showtopic=59295&st=0&a
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