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Enlivening the frog and powering the Tortoise with the same DPDT -- or not

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  • Member since
    February 2021
  • 288 posts
Enlivening the frog and powering the Tortoise with the same DPDT -- or not
Posted by crossthedog on Saturday, September 25, 2021 9:31 PM

Hi all. I have installed a Tortoise and it works fine with a DPDT on/on switch. I'd like to use the same switch and add wires to power the frog and have its polarity change, rather than having a second switch just to change frog polarity. I know how I would hook up to the DPDT because I've been experimenting with wires and frogs and rails and I know what has to go where. What I DON'T know is if combining the two systems is electrically feasible or if it would short something.

Here's the plan:

The black lines represent components already in place. The blue lines represent what I want to add. I would double up connection on the three connections on one side of the switch, as shown. The center wire would go to the frog, and the other two would go one to each rail ahead of the points.

Will this work? What am I not seeing?

Thanks,

-Matt

 

 

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 20,110 posts
Posted by MisterBeasley on Saturday, September 25, 2021 10:03 PM

Your suggested implementation won't work.  Sorry.

But, that's exactly what the other terminals on the Tortoise do for you.  Use one of the SPDT sets to power the frog.  Two posts connect to track power, and the third post goies to the frog.  The diagram showing which posts to use is with the Tortoise.  Don't solder the track power wires until you've tested the frog polarity in each point position.

It takes an iron man to play with a toy iron horse. 

  • Member since
    February 2021
  • 288 posts
Posted by crossthedog on Sunday, September 26, 2021 12:22 AM

MisterB, this is great news, thanks. I looked again at Figure 2 in the Tortoise instructions, and after your comment and rereading the instructions with this idea in mind, the picture suddenly makes sense. It seemed over my head when I first installed the Tortoise so I blocked it out of my memory, but now I see that the schematic is showing two internal switches, with wire from connection post 4 going to the frog and 2 and 3 going to the rails. 

I'll try it out tomorrow (and yes, I'll wrap the wires through the holes first to test before soldering them). Thanks for replying, MB. I'm slowly starting to get this electrical stuff, and so far everything on the layout is working perfectly, with 10 separately powered blocks and also DCC when I want it. 

Before embarking on the quest to power my frogs, I ran some tests with my DC steamers -- used some lengths of wire, drilled a few holes, touched a wire to this or that rail -- and found that powering the frogs competely solved the problem of the locos stalling on the turnouts. So I'm committed to getting them all wired eventually, Tortoises for crossovers and hard-to-reach locations and Caboose manual throws for easy access spots.

-Matt

Returning to model railroading after 40 years and taking unconscionable liberties with the SP&S, Northern Pacific and Great Northern roads in the '40s and '50s.

  • Member since
    January 2017
  • From: Southern Florida Gulf Coast
  • 14,526 posts
Posted by SeeYou190 on Saturday, October 16, 2021 12:22 AM

crossthedog
Will this work? What am I not seeing?

That will not work.

However, you can buy 3PDT (three pole double throw) toggles for less than $4.00 each, and they will do what you want.

I have used these when I needed both sets of Tortoise contacts for signal logic.

You will want switches that are set up as on/on and non-locking. This is what I found in a quick search.

-Kevin

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

  • Member since
    July 2009
  • From: somerset, nj
  • 3,854 posts
Posted by gregc on Saturday, October 16, 2021 4:01 AM

MisterBeasley
But, that's exactly what the other terminals on the Tortoise do for you.  Use one of the SPDT sets to power the frog. 

make sure of machine polarity/alignment

make sure of rail connections and correct polarity to frog

greg - Philadelphia & Reading / Reading

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