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Can DPDT subsitute for SPDT

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  • Member since
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  • From: Shenandoah Valley The Home Of Patsy Cline
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Can DPDT subsitute for SPDT
Posted by superbe on Friday, January 13, 2012 4:09 PM

I need SPDT momentary toggle switches but only have DPDT toggles on hand.

Has any one tried this and if so do you just use the connections on one side of the switch?

Thanks

Bob

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Posted by babefluff on Friday, January 13, 2012 4:22 PM

That will work.

 

Scott

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Posted by rrinker on Friday, January 13, 2012 4:44 PM

Yup, just use one side or the other, a DPDT is just two SPDT in the same case, with one handle.

Are the DPDT momentary? Those are sort of oddballs. They do make such things but they aren't common, SPDT momemtary is much more common. If you are using these for solenoid turnotu controls, they definitely have to be momentary, or else you will have to rig a pushbutton as well.

                                 --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by superbe on Friday, January 13, 2012 6:43 PM

My turnouts and switch motors are Peco which as you know are twin coil machines. My first batch of toggles were SPDT momentary but the second batch are the DPDT.

 Either I ordered wrong or I was sent the wrong ones but that was six months ago.

Everyone, thanks for the info and if the wind keeps up I'll be under the layout tomorrow. Too cold for the wife to go out.

Thanks

Bob

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Posted by ctclibby on Sunday, January 15, 2012 11:34 AM

Hi

Keep in mind that you do NOT have a momentary switch as you describe your dpdt switches -  I don't know how much continuous current a PECO machine can handle, you might want to give that a look.

Todd Hackett

 Libby, Montana 59923

 I take only pictures then leave footprints on railroad property that I know is not mine, although I treat it as such...

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Posted by superbe on Sunday, January 15, 2012 12:16 PM

Hey Todd,

I must not have described them correctly. When you flip the toggle in either direction on the DPDT the toggle springs back to the off position.

Murphys's law is working full force today. For the first time I wired two switch motors to one toggle switch ( SPST Momentary) and also for the first time I crimped the wires to spade connectors instead of soldering.

Both turnouts will work togther in one direction but not the other. I believe I've narrowed it down to one wire and will see as soon as my back feels up to it.

Thanks for the reply

Bob

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Posted by ctclibby on Sunday, January 15, 2012 2:59 PM

Boy, haven't seen a momentary DPDT in *years*.  Good that you got that as they should work just fine.  Heck, you even have another set of contacts to play with.

I hate it when my back tells me to quit!

ctclibby

Todd Hackett

 Libby, Montana 59923

 I take only pictures then leave footprints on railroad property that I know is not mine, although I treat it as such...

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Posted by superbe on Sunday, January 15, 2012 7:26 PM

"Heck, you even have another set of contacts to play with."

Now you have given me something to think about.

I replaced the wire with one with soldered connectors but it made no difference. After reversing the wires on the switch motor that only changed what position the toggle was in to throw the turnout.

For some reason the same coil in both motors isn't getting enoufgh juice. One turnout takes two throws of the toggle to turn to the diverging route and the other one takes 4 or more. They both snap for the straight through route with one push on the toggle.

It's next to impossible to use a meter to check the wires when you using a momentary toggle, not enough hands.

If I can't find the trouble I'll take your suggestion and replace the SPDT with the DPDT and join the turnouts at the toggle rather than at terminal strips.  I'm thinkg the trouble is at the strips.

Bob

AS for my back that's a convient excuse when I get frustrated.

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Posted by rrinker on Monday, January 16, 2012 6:18 AM

 The wires conencted at the strip should be your common from both coils (usually the black wire, or the middle one of the 2 condustor wire). If that were off, the turnout wou;dn't move either way. But if you managed to get one side to the common and the common to one side of the toggle, that would do it. Twin coils are pretty straightforward, the middle is usually common to both coils, that goes to one side of the power supply. The left most and right most wires are each individual coil and go to the outer terminals of the toggle, The center of the toggle goes to the other side of the power supply.

                   --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by SMassey on Tuesday, January 17, 2012 12:25 PM

If you used a SPST switch it will only be able to throw in one direction.  If you have DPDT switches that are not momentary you can simply add a pushbutton momentary to the mix and get the momentary action that way.  This is what I have done on my control panel for my staging yard. 

 

Here is a schematic of the SPDT with Momentary:

 

Here is my setup for my control panel.

Note the open hole is for a power LED

 

Massey

A Veteran, whether active duty, retired, national guard, or reserve, is someone who, at one point in his or her life, wrote a blank check made payable to "The United States of America" for an amount of "up to and including my life."

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Posted by superbe on Tuesday, January 17, 2012 1:54 PM

Massey,

I described my toggles incorrectly. You are correct and what I have are the SPDT.

You certainly do neat work. I won't be poasting any pictures of mine.

I haven't had a chance yet to get back under the layout.

Thanks,

Bob

 

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Posted by superbe on Monday, January 23, 2012 3:49 PM

Well it has been 10 days since I started wiring two twin coil switch motors to one DPDT Momentary toggle switch. The idea was to save time hooking them up and only have one toggle to throw.

 

The immediate results were that one turnout would snap for the through position and the other turnout sometimes need and extra push on the toggle. Both struggled to but wouldn't go to the divergent route.

I spent many hours under the layout checking and replacing wires with no luck. 

Today as a last resort I disconnected one of the turnouts from the toggle and the one that was hooked up worked fine. After hooking up the other one to a DPST Momentary it two works A-OK.

I don't know what in the heck went wrong but from now on it is one toggle for each turnout.

Bob

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Posted by BroadwayLion on Monday, January 23, 2012 4:18 PM

The problem is not with your control switch. Or even your wiring. It has to do with the placement of your turnout and its motor. There is a bit of friction there which needs to be remedied. Some graphite in the motor the linkages and points may help.

Just Like 1:1 trains. Get out with a broom, and clean off the switch points.

 

ROAR

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Posted by fwright on Monday, January 23, 2012 4:24 PM

superbe

Well it has been 10 days since I started wiring two twin coil switch motors to one DPDT Momentary toggle switch. The idea was to save time hooking them up and only have one toggle to throw. 

The immediate results were that one turnout would snap for the through position and the other turnout sometimes need and extra push on the toggle. Both struggled to but wouldn't go to the divergent route.

I spent many hours under the layout checking and replacing wires with no luck. 

Today as a last resort I disconnected one of the turnouts from the toggle and the one that was hooked up worked fine. After hooking up the other one to a DPST Momentary it two works A-OK.

I don't know what in the heck went wrong but from now on it is one toggle for each turnout.

Bob

Sounds like your power supply is not beefy enough to throw two switch machines simultaneously.  A Capacitive Discharge unit will do what you want, and save your toggles and switch machines, and allow you to use your present power supply.  A CD unit is easily built from a few bucks worth of parts from circuits found online.  Or buy one from Circuitron.

my thoughts, your choices

Fred W

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Posted by fwright on Monday, January 23, 2012 4:24 PM

superbe

Well it has been 10 days since I started wiring two twin coil switch motors to one DPDT Momentary toggle switch. The idea was to save time hooking them up and only have one toggle to throw. 

The immediate results were that one turnout would snap for the through position and the other turnout sometimes need and extra push on the toggle. Both struggled to but wouldn't go to the divergent route.

I spent many hours under the layout checking and replacing wires with no luck. 

Today as a last resort I disconnected one of the turnouts from the toggle and the one that was hooked up worked fine. After hooking up the other one to a DPST Momentary it two works A-OK.

I don't know what in the heck went wrong but from now on it is one toggle for each turnout.

Bob

Sounds like your power supply is not beefy enough to throw two switch machines simultaneously.  A Capacitive Discharge unit will do what you want, and save your toggles and switch machines, and allow you to use your present power supply.  A CD unit is easily built from a few bucks worth of parts from circuits found online.  Or buy one from Circuitron.

my thoughts, your choices

Fred W

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Posted by rrinker on Monday, January 23, 2012 4:42 PM

 Definitely on the capacitor discharge supply. It will make everything snap with authority, and also prevent damage if you hold one of the toggles too long. Easy to build, or you can buy a commercial one, inexpensive. Circuitron has one, and a guy I just bought a brass loco from on eBay hadone and didn't know what it was, I helped him with a more accurate description of what he had, it went unsold for a mere $8.95 and it has a HUGE capacitor on it, LOTS of power.

 Several other advantages, less arcing of the toggle contacts, and a solid but short jolt of power to make the switch motors snap into position. And no dimming lights if you use the same power pack to run street and structure lights.

                        --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

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Posted by superbe on Monday, January 23, 2012 7:56 PM

The turnouts are Peco with Peco switch motors and a Peco CDU to power them.

After reading the suggestions about the CDU I ran a little experiment.

First I repeatedly flipped a turnout back and forth without hesitation and there was no pause at the turnout...

However, when I tried two different turnouts at the same time only one turned. It took another push to get the second turnout to snap, but this is still much much better than when the two were hooked up to the DPDT toggle. And of course wouldn't happen while running trains.

With regards to the DPDT toggle does the wire going to the CDU attach to the center connector? The reason I ask is because 2 at one end and the 2 in the center face one direction while the 2 at the other end face in the opposite direction.

The feeds from the CDU are going to a terminal strip and then to a second one. Perhaps this is causing a loss of power or maybe the CDU wasn't designed to operate multiple turnouts simultaneously.

One of the lessons I've learned from model railroading is to have patience.

Bob

 

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Posted by rrinker on Tuesday, January 24, 2012 6:31 AM

 The power supply goes to the middle terminal of the switch. One coil connects to one end, the other coil to the other end. If one flips the wrong way, just swap the wires on the end terminals. Ig machine 1 needs coil 1 to activate on the top terminal and machine 2 in the crossover needs coil 2 to activate for the same switch position, then the top terminal of teh switch would have the wire from coil 1 of machine 1, and coil 2 of machine 2.

Also remember toggle switches connect the opposite terminals from the handle position. So if you are looking at the back of the toggle, the terminal side, when you flip the handle UP it conencts the middle and BOTTOM terminals. For signle turnouts, say a basic siding, if flipping the toggle to the straight route sets it for diverging, you can flip the top and bottom wires, or just turn the toggle around.

                    --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
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Posted by superbe on Tuesday, January 24, 2012 10:55 AM

That's the way I had the wires hooked up.

I was just puzzeled as to why the turnouts work perfectly when on SPDT but not when both are on the DPDT.

Any way they are all working so to everyone

Thanks,

Bob

 

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