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Model Railroading > SPDT and relay to reverse polarity for Tortoise Switch Machine?


Date: 02/18/21 21:46
SPDT and relay to reverse polarity for Tortoise Switch Machine?
Author: wabash2800

I haven't moved up to using relays in wiring yet. Can I operate a Tortoise switch machine with an SPDT switch and a relay?

How is it wired?

I know how to do it with a DPDT switch, but the kind of snap relay micro switch I want to use as a DPDT is much more expensive than one offered as an SPDT.

Victor A Baird
http://www.erstwhilepublications.com



Edited 2 time(s). Last edit at 02/19/21 06:14 by wabash2800.



Date: 02/18/21 22:26
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: santafesteve

The least expensive way is with 1 power supply and 1 DPDT switch.  The next least expensive way is with 2 power supplies and 1 SPDT switch like they show in the switch machine installation instructions. I can’t understand why you would want to do it anyway else. 

Steve Kelly CSMRRC



Date: 02/19/21 05:40
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: funnelfan

As long as the relay is a DPDT, then yes, you can wire the SPDT switch like a simple on-off switch for the relay coil and let the relay switch polarity. I would have to experiment, but I think if you had a 12v AC suppy, I'm sure you can make it work with a SPDT and a couple of diodes.

Ted Curphey
Cheney, WA



Date: 02/19/21 06:19
SPDT and relay to reverse polarity for Tortoise Switch Machine
Author: wabash2800

I need about 40 snap action micro switches for a special application (physical characteristics). The micro SPDT snap action switches are very cheap. A micro snap action DPDT switch starts out at about $7...

Victor A. Baird
http://www.erstwhilepublications.com

santafesteve Wrote:
-------------------------------------------------------
> I can’t understand why you would
> want to do it anyway else. 
>
> Steve Kelly CSMRRC



Edited 3 time(s). Last edit at 02/19/21 06:42 by wabash2800.



Date: 02/19/21 06:48
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: wabash2800

Thanks Ted. A signal maintainer friend is back from training from out-of-state now. (It was not railroad related. He is also private jet pilot, but that is another story.)

I was able to contact him, and he says it will be no problem at all. In fact, in another application with crossing gates he wants to show me how to do that anyway. I will share what I have here when I get it worked out.

Victor A. Baird
http://www.erstwhilepublications.com

funnelfan Wrote:
-------------------------------------------------------
> As long as the relay is a DPDT, then yes, you can
> wire the SPDT switch like a simple on-off switch
> for the relay coil and let the relay switch
> polarity. I would have to experiment, but I think
> if you had a 12v AC suppy, I'm sure you can make
> it work with a SPDT and a couple of diodes.



Edited 2 time(s). Last edit at 02/19/21 07:07 by wabash2800.



Date: 02/19/21 11:03
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: JUTower

I assume you already have the relays? The relays plus the SPDT switches probably cost more than DPDT switches which would be easier.  Regardless of that, you could use the same power supply to energize the relay coils and energize the switch machines (assuming 12V relays)...

See attached.




Date: 02/19/21 18:00
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: wabash2800

Thanks for your imput JUTower. Here is a grab shot of one of my levers and a SPDT snap-action, micro switch. I want the snap action micro switches for their physical characteristics to work with my levers. Snap action DPDT micro switches are available, but you can buy oodles of the SPDT snap-action, micro switches and DPDT relays for what you pay for one snap action micro DPDT switch. Though easier to wire, it would cost me about $300 for the DPDT snap action micro switches for my tower frame. Also, for some reason, my signal maintainer friend prefers the micro SPDTs. For sure, John has some other tricks up his sleeve.

As I mentioned before, I had used DPDT toggle slide switches but wasn't happy with the motion, even with bell cranks. I will show how I do this later. 

Victor A. Baird
http://www.erstwhilepublications.com

 



Edited 4 time(s). Last edit at 02/19/21 18:36 by wabash2800.




Date: 02/20/21 06:58
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: JUTower

Thanks for the photo - this makes a lot more sense now. Really interesting!



Date: 02/20/21 09:26
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: Kimball

Looks like you are developing a new product line...



Date: 02/20/21 14:07
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: funnelfan

Really, you can just replace the relay with a couple of diodes if you use a 12v AC power supply. The diodes will set polarity for the Tortoise motor.

Ted Curphey
Cheney, WA




Date: 02/20/21 14:13
Re: SPDT and relay to reverse polarity for Tortoise Switch Machin
Author: wabash2800

No Kimball, the lever is a modified Hump Yard Purveyance (name of company that makes them) lever that I also painted. (I apologize, but these photos have been posted here before.) The first picture is my frame with the painted 40 levers. The next photo is the unsatisfactory method I used with DPDT slide switches. Even with bell cranks, I was unhappy with the lever action. The last photo is my life-size model board with indicator lights and a track diagram. (I drew up the model board myself based on similar Wabash style model board in a tower I was familiar with and had a sign shop print it in color on a sheet of PVC plastic.  There really was a Fort Wayne Union Railway, but it went under the Wabash rather than at grade. 

After modifying the levers designed for choke cables and made of an engineering kind of plastic, I soda blasted them and then painted on Krylon paint for plastic. The number plates are an addition I made from U section plastic stock, but I had to use a special kind of adhesive to attach them to the levers. (The number plates are oversize, but you have to be able to see them!)  A model railroader that worked at the local hobby shop made both white and black decal numbers for the switch levers. ( I now can do that on my own.) I would have loved to have raised numbers, but it wasn't practical with what is available. Since I have four more interlockings to build, perhaps I can work that out in the future.)

This white levers are out-of-service levers; the signal levers are red; the derail levers are black and blue; facing point lock levers are blue; the switch levers are black, and the two levers for the east and west crossing gates are yellow and red. Just like the real thing, a bell will announce trains approaching the plant and indicator lights on the model board will show the location of trains. The green indicator lights will light up when a signal is lined and go out when the signal drops. I scratch-built the indicator lights as I could not find the ones I remember. The semaphores worked beautifully once I slowed them down, but John is going to show me how to wire them so that they will drop when a train passes them.(My semaphores simulate motorized semaphores.)

I could have built the frame like the real thing with levers interlocked within a frame with tappets and bars, etc., but don't want to spend that much time. And neither do I like the computer solution. As I plan it,  when the derails are open and set against a route, that will kill the power to that section of track and also cut power for the corresponding signals and turnouts. Technically, It is not a real interlocking, but it will work for now.

Victor A. Baird
http://www.erstwhilepublications.com


Kimball Wrote:
-------------------------------------------------------you 
> Looks like you are developing a new product
> line...



Edited 4 time(s). Last edit at 02/20/21 15:28 by wabash2800.








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