Wiring tortoise with Bipolar method & SPDT

beakie

Wiring tortoise with Bipolar method & SPDT

Postby beakie » Wed Nov 03, 2010 8:11 am

Hiya Guys

I wonder whether someone could help me with the wiring of 2x 12v supplies in series, as per the Tortoise instructions.

It’s the connection of the bus wire to both the -/+ terminals that’s confusing me. I have seen on schematics 12v+ and 12v- as power rails which similarly confuses me.

I guess I’m so used to positive and negative being apart because of short curcuits.

Would be grateful for any assistance

Regards

Dave

John Fitton

Re: Wiring tortoise with Bipolar method & SPDT

Postby John Fitton » Wed Nov 03, 2010 12:54 pm

Dave,

I use Fulgurex slow motion switch machines and they have a similar power supply requirement. Two independent (i.e., not off the same main controller or transformer) controllers are required. Connect one terminal of each one to the other. This effectively becomes a common ground (earth in UK). Set one of the controllers to give a positive voltage wrt this common earth, and the other controller to give a negative voltage. The magnitude of the voltage controllers the speed of the switch machine.

I use SPDT switches to operate the Fulgurex machines. They have three terminals, which for ease of description I call upper, centre, and lower. The positive terminal of the first controller goes to all the upper terminals of the SPDT switches, the negative terminal goes to the lower terminals. Each switch machine has two terminals. One is connected to the common ground. The other goes to the centre terminal of its controlling SPDT switch. I suggest standardizing all your swithc machines, colour coded, and with identical wire lengths, and using terminal blocks for ease of line replacement and servicing.

John

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grovenor-2685
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Re: Wiring tortoise with Bipolar method & SPDT

Postby grovenor-2685 » Wed Nov 03, 2010 2:05 pm

I guess I’m so used to positive and negative being apart because of short curcuits.


Its really just the same as wiring up controllers for common return wiring. The important thing is that the supplies come from seperate transformer windings and you only make the one connection between the two supplies.

Have you already obtained two power supplies? And if so what sort?

For the tortoises you don't need to use two transformers as they will happily work off half wave power and you can produce the required + and - by using a single transformer and a pair of simple diodes.

Regards
Keith
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Keith
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beakie

Re: Wiring tortoise with Bipolar method & SPDT

Postby beakie » Wed Nov 03, 2010 4:01 pm

Hiya Guys, thx for your replies...

Thx for your clear reply, john.

Upto now I have been using a spare 12v supply from a Gaugemaster model D (Twin Track) and wiring the turnouts with DPDT switches. I only had three turnouts at that stage. I have another 6 turnouts to wire and I am looking for a more permanant arrangement. I have used 3 tortoises so far, but acquired a 2 fulgerex motors.

Thanks keith, for your reply

grovenor-2685 wrote:
I guess I’m so used to positive and negative being apart because of short curcuits.


Its really just the same as wiring up controllers for common return wiring. The important thing is that the supplies come from seperate transformer windings and you only make the one connection between the two supplies.


Understand the principle involved in the Common Return Wiring, but the practicalities of achiveving confuse me Kieth.
Think this may be another thread on a different day lol

grovenor-2685 wrote:
Have you already obtained two power supplies? And if so what sort?


I havent yet, Kieth. I have been looking at the Guagemaster Unregulated AC Power supplies(Encased), even considered buying a chassis Mounting Transformer and carrying out all the necessary wiring, although this might be ambious for me. Its clear that my present arrangement, will have to change if I want to use SPDT with a comon Return to save on wire.

grovenor-2685 wrote:For the tortoises you don't need to use two transformers as they will happily work off half wave power and you can produce the required + and - by using a single transformer and a pair of simple diodes.

Not sure how this would work kieth, but sounds good. I'm always trying to budget so much a month, so cost is always a factor. So far I have tried to do things in modules. For Example, I want some nice levers and a good control panel and plan to construct these at a later stage. Just trying to get the track wired and working so I can ballast, so some of what i'm doing is temporary and my panel is functional at this stage.

I digress again.....

Many thanks again for your replies


EDIT: Just been looking at Instructions for AC with Steering diodes, on Tortoise instructions,think I understand this more, Kieth.

Many thx Dave

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Re: Wiring tortoise with Bipolar method & SPDT

Postby allanferguson » Thu Nov 04, 2010 12:42 am

beakie wrote:EDIT: Just been looking at Instructions for AC with Steering diodes, on Tortoise instructions,think I understand this more, Kieth.

Many thx Dave


Many years ago when we built Bonnybridge we used half wave AC for the points motors (Fulgurex I think). The motors were a little noisier, but not noticeable at an exhibition. It saved an awful lot of wire. We used the 16vAC output from an H & M controller I think. I attach the wiring schematic which may be helpful.
Principle of half wave control of switch machines.doc
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Re: Wiring tortoise with Bipolar method & SPDT

Postby allanferguson » Thu Nov 04, 2010 12:45 am

I'm sorry I meant the attachment to appear in the body of the message, but I obviously don't understand how to do it

Allan F

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Re: Wiring tortoise with Bipolar method & SPDT

Postby Paul Willis » Thu Nov 04, 2010 6:47 am

allanferguson wrote:I'm sorry I meant the attachment to appear in the body of the message, but I obviously don't understand how to do it

Allan F


Hi Allan,

If I can summarise it correctly without doing it at the same time, then you have done everything correctly apart from putting the image in the post itself.

When you have surfed to the file that you want to attach, and clicked "upload attachment", then you get an option to "add the file". This will leave it as an attachment to the message. There is then, next to it, a button labelled "Place inline".

If you position your cursor where you want the image to appear in the message, and click on this, it inserts a bit of code in the message that says "[attachment] xxx.jpg [/attachment]" or whatever the file is called, and the image mysteriously (well, not really...) appears:

Principle of half wave control of switch machines.doc


Now... In this case, your drawing was done in a word processor, and saved as a .doc file. That won't display in the web browser as it can't interpret it as an image. So what I did was download it, save it as a pdf file (using Cute PDF), then copy that document's contents into a graphics package (the GIMP) and save it as a .jpg.

Longwinded to wrote, although in reality it only took a few seconds. Both of the bits of software referred to are free to download, and very worthwhile (the Society adverts for magazines are all drawn in GIMP, so you can see that it produces work to professional publishing standards - comments on the artistic content not necessary!). And you get this:

Half wave.jpg


The real moral of the story is that word processors are for text and graphics packages, even simple ones like Microsoft Paint, which I recall is used to great effect by Russ Elliott, are for images.

HTH
Flymo
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beakie

Re: Wiring tortoise with Bipolar method & SPDT

Postby beakie » Thu Nov 04, 2010 7:15 am

Hiya Guys

Thanks for your post Allan and your time making the schematic, it was most helpful. I always think a picture tells a thousand words

allanferguson wrote:I'm sorry I meant the attachment to appear in the body of the message, but I obviously don't understand how to do it


Absolutely no worries Allan

Allan, I note you have placed diodes on the machine, as well as the Ac supply. Are these to smooth out the current more.

I have some N4001 diodes, could I use these in this arrangement.

Regards

Dave

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Re: Wiring tortoise with Bipolar method & SPDT

Postby nigelcliffe » Thu Nov 04, 2010 8:17 am

beakie wrote:I have some N4001 diodes, could I use these in this arrangement.


Yes.

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Re: Wiring tortoise with Bipolar method & SPDT

Postby grovenor-2685 » Thu Nov 04, 2010 9:46 am

Allan, I note you have placed diodes on the machine, as well as the Ac supply. Are these to smooth out the current more.

No the diodes at the machine are not required for a tortoise (there would be nowhere to put them) but for the fulgurex/lemaco they are needed so that the cut off contacts are not bypassed, I rather thought that they are already built in as they are also needed to work it with a dpdt switch, but its a long time since I used one. (Noisy horrible things ;) )

If you want to smooth the current, eg if the noise annoys you, then a couple of capacitors can be added.
Regards
Regards
Keith
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Re: Wiring tortoise with Bipolar method & SPDT

Postby allanferguson » Thu Nov 04, 2010 1:37 pm

Thanks, Flymo, for the tutorial. One of these days I'll get the hang of this computer thingy ;)

Beakie, I found the original drawing for the Bonnybridge layout, which confirms the point made by grovenor-2685. I can't remember whether the diodes were built in -- certainly there were moulded recesses for them in the motor base.

Now lets see if I can get it right this time...
Bonnybridge Points Wiring.jpg


Bingo!

Incidentally, we used DPDT switches, and changed the crossing polarity with them at the panel, rather than relying on the C/O cwitch in the motor; this meant another wire to each turnout thus negating the saving we'd already made!
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Re: Wiring tortoise with Bipolar method & SPDT

Postby Russ Elliott » Thu Nov 04, 2010 2:00 pm

allanferguson wrote:Incidentally, we used DPDT switches, and changed the crossing polarity with them at the panel, rather than relying on the C/O cwitch in the motor; this meant another wire to each turnout thus negating the saving we'd already made!

Yes, but look on the bright side, Allan - if you didn't use split potential, that would have involved 3PDT switches!

beakie

Re: Wiring tortoise with Bipolar method & SPDT

Postby beakie » Thu Nov 04, 2010 4:09 pm

hiya Guys

Thanks Kieth and Allan, lots of food for thought here . Thanks for digging out orginal diagram Allan.

On the fulgurex I have, the diodes are built in, so I guess they are the diodes in your diagram.

Interesting thought on x polarity switching, I have had an auxillary sw on Tortoise fail for xing .

Thanks for all the info guys, much appreciated.

Regards

Dave


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