# Set multiple tortoise switches from a single toggle



## gordo53 (Jul 28, 2019)

Our yard occupies an entire small former bedroom and consists of 7 concentric reverse loops. There are six sidings plus the main. On the inbound leg, the tortoise wiring is straight forward as each siding connects directly with the main. However, on the outbound leg, four sidings converge into two, the resulting two converge, and that track is joined by each of the remaining two sidings before rejoining the main. My plan is to be able to engage each siding with just a single toggle switch. In other words, with just a single toggle the appropriate (multiple) tortoises will be set. I have a design, but it's complicated. I'm thinking some of you must have done something similar and hopefully simpler. Thanks in advance for any and all advice.


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## gunrunnerjohn (Nov 10, 2010)

How about a diode matrix to trigger a single relay based on the positions.

With the proper spring tension, you can simply drive through the tortoise machine on the outbound side, you don't necessarily have to switch the points.


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## gregc (Apr 25, 2015)

there are several approaches depending on whether you are using snap switches or tortoise like switch machines

an approach uses diodes to direct a pulse to snap switches. however this requires a more beefy supply since power is routed to multiple coils at the same time

for tortoise machines, latching relays can be selected using diodes to change polarity or route +/- 12V to the switch machines


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## gordo53 (Jul 28, 2019)

We use tortoise switches.
Yes, diodes are a must.
I was not aware you could run through a switch if the spring was weak enough. The spring bars we have are quite stout. Will need to get some new ones and try it. Thanks.


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## gregc (Apr 25, 2015)

a latching relay has two coils. Power is applied to a coil to switch it's state which it holds after power is dropped from the coil

momentary switches can be added for each track and diodes connected between that switch and the appropriate coil for each turnout that needs to be switched. there will be multiple diodes to each relay coil unless there is only one connection.

not the least expensive approach.

dpdt relays are need is a single 12V supply is used and polarity must be reversed. spdt if both +12 and -12V supplies are used and simply routed


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## DonR (Oct 18, 2012)

Tortoise powered turnout points are held in place
by the motor, not springs, so the trains can't push
the rails aside.

If it's not too late, you could change the turnouts to
twin coil motors and use the very simple and easy to operate
Diode Matrix system. You push a panel button in any yard track and all turnouts in the route are set. Requires only
a barrier strip terminal board and a few diodes.

It's going to be quite complex to have the same sort of
system using Tortoise motors due to the fact they use
reversing polarity DC voltage.

Don


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## traction fan (Oct 5, 2014)

*Simple control for multiple Tortoise motors*



gordo53 said:


> Our yard occupies an entire small former bedroom and consists of 7 concentric reverse loops. There are six sidings plus the main. On the inbound leg, the tortoise wiring is straight forward as each siding connects directly with the main. However, on the outbound leg, four sidings converge into two, the resulting two converge, and that track is joined by each of the remaining two sidings before rejoining the main. My plan is to be able to engage each siding with just a single toggle switch. In other words, with just a single toggle the appropriate (multiple) tortoises will be set. I have a design, but it's complicated. I'm thinking some of you must have done something similar and hopefully simpler. Thanks in advance for any and all advice.




gordo53;

I use a very simple system I found in Model Railroader Magazine. The article appeared in the November 2000 issue.It's titled "Route Control for slow-motion turnout motors" by David K. Smith. This system is bone simple analog, no computer chips at all. It uses a center-tapped transformer, a few diodes and resistors, two capacitors, and one rotary switch. That's it! The photo below shows my control panel for Cedar Falls, WA. The right-hand, orange, part controls the turnouts. The white part on the left only controls the lights and motorized doors of the engine house above the panel.
The single rotary switch is simply set for whatever track you want, and all the turnouts are automatically set for that track. You can enlarge the photo by clicking on it. Two clicks gives a detailed view.

You can probably order a back issue, or download the article, from Model Railroader for a fee. [email protected] Or (800)-533-6644. I would send you a copy of the article, but, the article is copyrighted, which, legally, makes it a federal crime for me to send you a copy, and anyone, including federal law enforcement, can look in on this forum. 

good luck, have fun;

Traction Fan :smilie_daumenpos:


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## gunrunnerjohn (Nov 10, 2010)

DonR said:


> Tortoise powered turnout points are held in place by the motor, not springs, so the trains can't push the rails aside.


If you use a light enough spring wire, they will open as you go through, I've seen it first hand. We have also done the same with the NJI switch machines.


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## Lemonhawk (Sep 24, 2013)

You can use Digitrax DS64's and program the routes in them. It's designed to the use one push button to set a route. Like most Digitrax products they are a marvel of versatility hence have complicated manuals. If you want to involve a computer you can use JMRI to control routes. Of course if your good at programming an Arduino, you can roll your own controller! Note that in use the DS64 does not need Loconet, but to set up the route programming you will need a DCC connection. Nice thing about DS64's is that they can be set up to use their own power supply and not use up track power like switch-its.


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## gordo53 (Jul 28, 2019)

I emailed a request for a copy of the November 2000 article. Couldn't download it (unless I have a digital membership). Thanks for the tip.


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## gregc (Apr 25, 2015)

see design procedure for yard ladder


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## gordo53 (Jul 28, 2019)

Thanks Greg. Being a relative newbie, I didn't know the term "yard ladder". One of the examples in that piece is just about an exact match to what I'm working on. Looks like a simpler solution than mine which is a very good thing. I'm using toggle switches instead of a rotary, but the logic is the same. I had to chuckle. I was a software developer for 20 years. The "truth" tables were not unfamiliar.


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## traction fan (Oct 5, 2014)

*Toggle vs. rotary*



gordo53 said:


> Thanks Greg. Being a relative newbie, I didn't know the term "yard ladder". One of the examples in that piece is just about an exact match to what I'm working on. Looks like a simpler solution than mine which is a very good thing. I'm using toggle switches instead of a rotary, but the logic is the same. I had to chuckle. I was a software developer for 20 years. The "truth" tables were not unfamiliar.




gordo53;

The circuit recommended by gregc sounds like the same one I suggested. I'm glad he could furnish you with more information.
Using that circuit, the higher positive, "overriding " voltage is supposed to be applied to only one route at a time. With the specified rotary switch, this happens Automatically, since the switch can only supply power to one of its terminals at a time. With a group of toggle switches though, it's quite possible to have more than one switch "on" at a time, which would apply the higher overriding voltage to two, or more, routes simultaneously, possibly telling one Tortoise motor and gear train to rotate both clockwise and counter-clockwise, at the same time. I don't know whether that would damage your expensive Tortoise machines, or not, But I recommend using the rotary switch as an extra safeguard.
Obviously, you would not likely select both track 'A',and track 'D', at the same time intentionally, but accidents do happen, and I've learned that Murphy's law is very true, and worth providing insurance against.
Spring-loaded, momentary, toggle switches would seem like a possible solution, except that while pushing one to the "on" position will cause the circuit to work normally, the second you let go of it, things will go back the way they were. The circuit only works by feeding that overriding voltage to one route's motors, and keeping it there constantly. The rotary switch does this automatically too.

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

not sure what you're getting at above. this design depends on the rotary switch to select only a single route and maintain voltage


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## traction fan (Oct 5, 2014)

*Agreed*



gregc said:


> not sure what you're getting at above. this design depends on the rotary switch to select only a single route and maintain voltage


gregc;

I know. That is what I was getting at. The OP said he wanted to use (presumably several) toggle switches instead of the single rotary switch. That can work, but it has the built-in potential for having two toggles "on" simultaneously and possibly telling a Tortoise motor to run both forward and reverse at the same time. Using the rotary switch, as designed, eliminates this possibility. So I'm recommending that he use the circuit as designed, with a single rotary switch, not an array of toggle switches.

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

gordo53 said:


> I'm using toggle switches instead of a rotary, but the logic is the same.


i missed this.

not sure how you can use toggle switches for route selection.


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## traction fan (Oct 5, 2014)

*Toggle switches*



gregc said:


> i missed this.
> 
> not sure how you can use toggle switches for route selection.


gregc;

Not that I advocate this, I do not. However it could be done. Think of how the rotary switch in the original circuit operates. There is one common terminal which has the voltage that is used to select the route on it. By rotating the knob attached to the rotary switch you connect that common terminal to one of several output terminals ranged around the fiberglass disc of the rotary switch. In short, you connect the voltage to one terminal and keep that voltage constantly on that same terminal to operate the circuit as designed.

Now think of a row of SPST (on-off type) toggle switches, built into a control panel, with each switch set into a line representing each of the yard tracks.
If we feed the operating voltage to all the "input" terminals of all the toggle switches, then we can flip one toggle switch to its "on" position and feed the voltage to the output terminal of that switch, and keep it there. Electrically, this does the same thing as the rotary switch. However, it is absolutely dependent on the human operator. He has to flip only one toggle switch "on" at a time, and always remember to switch that toggle switch "off" before selecting a different track, by turning that track's switch "on." 

While this is quite doable, you can probably see the potential for human error inherent in this arrangement. By contrast, a rotary switch's mechanical layout prevents you from even being able to select two routes at once. It will only allow voltage to be connected to one route's output terminal at a time.

regards;

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

traction fan said:


> However, it is absolutely dependent on the human operator.


guaranteed to fail



momentary buttons could be used (again assuming ???) only one button is pressed at a time, and held until all motors have completed travel. The tortoise switch machine are likely to hold the point in position.


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## traction fan (Oct 5, 2014)

*Agree and disagree*



gregc said:


> guaranteed to fail
> 
> 
> 
> momentary buttons could be used (again assuming ???) only one button is pressed at a time, and held until all motors have completed travel. The tortoise switch machine are likely to hold the point in position.




gregc;

I agree with the idea that humans can, and sooner or later will, fail. 

I disagree with the momentary pushbutton idea though. Even if the operator pushed one button, and held it down, (unlikely, at least consistently, every time, forevermore.) The second he let go the overriding voltage would be cut off, and the constant, lower voltage would drive the Tortoise back the other way.

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

traction fan said:


> The second he let go the overriding voltage would be cut off, and the constant, lower voltage would drive the Tortoise back the other way.


there should be no voltage once the button is released


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## traction fan (Oct 5, 2014)

*there is in my circuit*



gregc said:


> there should be no voltage once the button is released


gregc;

The circuit I recommended to him, from the November 2000 model railroader uses constant -9 volts DC to set the Tortoise motors to a default or normal position. This voltage is overridden by +18 volts DC to set any turnouts that need to change point position to the position required for a route. Turnouts already in the right position are left with the -9 volts. So, at least in this circuit, there is always some voltage on all the Tortoise motors, holding them firmly in one position or the other. Perhaps your circuit is different?

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

how is the -9V "over ridden"?


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## traction fan (Oct 5, 2014)

gregc said:


> how is the -9V "over ridden"?


 -9VDC +18VDC= +9VDC

"Normal" turnout position with the Tortoise pushing the points against the stock rail on one side of the turnout = the constant -9 VDC. Add the override voltage of +18VDC and you get a net value of +9VDC. 

-9VDC turns the DC motor one way and +9VDC turns the motor the opposite way. One motor terminal is ground so + or - with respect to the zero volts at ground will cause the motor to turn one way or the other.

Traction Fan


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## gregc (Apr 25, 2015)

you can't be saying that there is -9V on one of the tortoise terminal and by connecting it also to 18V you 9V ???

the other terminal is at ground? right?


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## traction fan (Oct 5, 2014)

gregc said:


> you can't be saying that there is -9V on one of the tortoise terminal and by connecting it also to 18V you 9V ???
> 
> the other terminal is at ground? right?


Of course I can be saying it, I have said it.
I also have the circuit on my layout, and it works.

When +18 volts is applied to one of the motor terminals that has -9 volts already on it, the "first" +9 volt portion of that +18 volts cancels out the -9 volts that is already there. The remainder of the + 18 volts is +9 volts. So, the net result is that the voltage on that terminal changes from -9 volts to + nine volts, when the +18 volts is applied. 

The math works like this;

(-9) + (+18) = (+9) 

It's simple addition, using one negative number in the equation. When you add a negative number it is basically the same as subtraction. So, if the terminal starts off at a potential of -9 volts, and you add +18 volts to that existing -9 volts, the result is +9 volts. I don't know any simpler way to explain it.

All the positive, and negative, voltages are in respect to, or referenced to, ground, which is zero volts. - 9 volts is lower than zero. +18 volts is higher than zero.
One end terminal of the center-tapped transformer and one terminal of each Tortoise motor are all connected to each other as a common ground. The center tap of the transformer outputs an AC voltage that when rectified by one of the diodes becomes the -9 VDC. The other transformer terminal, (the one furthest from the ground terminal) outputs a higher AC voltage, which when rectified by the other diode, (which is connected the opposite way as the first diode) becomes the +18 VDC.

I can't explain it any further than that. I certainly don't want to get into an online argument with you. 

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

traction fan said:


> When +18 volts is applied to one of the motor terminals that has -9 volts already on it, the "first" +9 volt portion of that +18 volts cancels out the -9 volts that is already there.


connecting together two power sources at different voltages with a common ground creates a short

the voltage of multiple voltage source in series (but not shorted together) add.



traction fan said:


> One end terminal of the center-tapped transformer and one terminal of each Tortoise motor are all connected to each other as a common ground. The center tap of the transformer outputs an AC voltage that when rectified by one of the diodes becomes the -9 VDC. The other transformer terminal, (the one furthest from the ground terminal) outputs a higher AC voltage, which when rectified by the other diode, (which is connected the opposite way as the first diode) becomes the +18 VDC.


the schematic shows how a center tap transformer can be wired to provide two voltage sources with a common ground.

one terminal of a tortoise switch machine can be connected to the GND and the other terminal to either +12V or -12V


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## gordo53 (Jul 28, 2019)

Well, FWIW, failure is something I am well acquainted with. I will post results as soon as they're available. We are currently waiting on an order of new Tortoise machines as most of the turnouts in the old layout were manual. 
This might help explain what we're doing. Our power source for the Tortoises is two 9v power supplies hooked up in series with the common wired between the two. It is option 2 in the Tortoise instructions. Tends to make wiring a bunch of Tortoises easier. I've done precious little with electronics for over 50 years - since I was in amateur radio in high school, so it's fun and also instructional. Thanks for your help.


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## traction fan (Oct 5, 2014)

*different circuit*



gregc said:


> connecting together two power sources at different voltages with a common ground creates a short
> 
> the voltage of multiple voltage source in series (but not shorted together) add.
> 
> ...


 gregc;

The circuit in your schematic is a very common one for building a split +/- power supply. It however is not the same circuit I saw in the Nov. 2000 Model Railroader, and recommended to the OP. As stated in my last response, and my very last attempt to explain that circuit to you, The Nov. 2000 MR circuit has one of the END terminals grounded, NOT THE CENTER TAP, as in your schematic. 
Just out of curiosity, are you an electrical engineer? I'm not, and, of course, you can answer that question, or not.
I'm just curious about your rather fierce tenacity in this thread and your apparent desire to be right, have the last word, and prove me wrong. Think, or believe, whatever you want, I feel this ridiculous debate over nothing has gone on long enough. 

Traction Fan


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## gregc (Apr 25, 2015)

traction fan said:


> It however is not the same circuit I saw in the Nov. 2000 Model Railroader, and recommended to the OP.


i wish you could post diagram. 

maybe that circuit connects the center (-9V) to one tortoise terminal and connects either (not both at the same time) to what they call ground or +18V to the other tortoise terminal?



traction fan said:


> are you an electrical engineer?


yes



traction fan said:


> I'm just curious about your rather fierce tenacity in this thread and your apparent desire to be right, have the last word, and prove me wrong.


i hope no one attempts to connect power supplies at different voltages with a common ground to the same point since a short will likely damage equipment



traction fan said:


> When +18 volts is applied to one of the motor terminals that has -9 volts already on it, the "first" +9 volt portion of that +18 volts cancels out the -9 volts that is already there.


the way you explained this -- connecting 18V to a terminal that is already connected to -9V -- is a short.

if one side of the transformer is "ground" the the other side could be +18V and the middle +9V. I don't know how -9V is possible


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## Lemonhawk (Sep 24, 2013)

I was thinking my DS64's had a complicated way to make routes. I beginning to think that it's the easier approach. A simple push button on the track ladder you want to activate. Uses a simple 12v power supply. Will run stall motors or solenoids(CD). talks to JMRI via loconet or track.


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## gregc (Apr 25, 2015)

traction fan
i believe Matrix control for Tortoise switch machines by David Smith describes the circuit you've been referring to.

the schematic diagrams in that article (cached google image below) shows that while -9V may be directly applied (or thru a diode) to a tortoise terminal, the 18V is connected to the same terminal thru 2.2K 1/2 Watt resistor.

when the -9V is connected, there is 27V across the resistor, passing 12 ma and ~-9V at the terminal.

when the -9V is not connected, something less that 18V is on the terminal, depending on the current being draw.


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## traction fan (Oct 5, 2014)

gregc said:


> i wish you could post diagram.
> 
> maybe that circuit connects the center (-9V) to one tortoise terminal and connects either (not both at the same time) to what they call ground or +18V to the other tortoise terminal?
> 
> ...


 I'm done.

Traction Fan


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## gordo53 (Jul 28, 2019)

Thanks guys. I didn't mean to cook up controversy.


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## traction fan (Oct 5, 2014)

*Not your fault*



gordo53 said:


> Thanks guys. I didn't mean to cook up controversy.


gordo53;

You didn't. 

Don't sweat it. Did you get your copy of the article from Model Railroader yet?

Traction Fan :smilie_daumenpos:


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## gordo53 (Jul 28, 2019)

The back issue is no longer available and the website has changed. I think I need to have a digital subscription ($99) to get access. Greg sent me a link to a more recent article that is probably pretty close. I think I've got it. My new Tortoise switches showed up today so I'll give it a shot in the next few days. I'll figure it out. Half the fun is getting there. Thanks again for everything.


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## traction fan (Oct 5, 2014)

*Matrix control for slow motion switch machines*



gordo53 said:


> The back issue is no longer available and the website has changed. I think I need to have a digital subscription ($99) to get access. Greg sent me a link to a more recent article that is probably pretty close. I think I've got it. My new Tortoise switches showed up today so I'll give it a shot in the next few days. I'll figure it out. Half the fun is getting there. Thanks again for everything.


gordo53;

I looked at the link in gregc's most recent reply, and that is the exact same circuit that was in the magazine. Not surprising since it has the same title and author. If you build it the way its diagramed, it will work. I've built two of them and they both work fine. I do recommend that you use a rotary switch, as shown in the link rather than toggle switches.

good luck, have fun;

Traction Fan :smilie_daumenpos:


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## gregc (Apr 25, 2015)

Now that it is clear what Traction Fan was describing, i think the article posted on MR by Thomas Hunt is more conventional, though requires using a 2-pole rotary switch. It uses 2 12VDC supplies which you may already have on hand.

While the Smith avoids the use of a 2-pole rotary switch, it provides positive voltage to the switch machines thru a 2.2K limiting resistor that I believe will cause them to change position very slowly in the one direction and somewhat faster in the other (-9V). The power supply is also somewhat unconventional, not exactly replaceable by two separate DC supplies.

both rely on diodes to control multiple turnouts for a selected route.

for me, it was interesting to read about different approaches to solving this type of problem. My experience is somewhat different for dealing with route control through interlocks


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## gordo53 (Jul 28, 2019)

Ok, so here's my best attempt at a wiring diagram using dpdt toggle switches to wire a yard ladder. Please don't laugh. I'm not an electrical engineer. I finished it up today and it does work. Small victory for the electronically challenged mind!


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## gregc (Apr 25, 2015)

can you explain how to use the toggle switches?


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## gordo53 (Jul 28, 2019)

Sure. All the toggles are normally set to mainline. There is one toggle per siding. To select the siding simply flip the appropriate switch. When the siding is deselected, all the tortoise machines revert back to mainline. I should add that the lower number sidings take precedent over the higher numbers. In other words, the lower number tortoise machine (turnout) is normally (when no siding is selected) closed.


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## gregc (Apr 25, 2015)

so you only set one, and only ever set one toggle to a siding?


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## gordo53 (Jul 28, 2019)

Yes, we will only operate one siding at at time. When the siding is selected all the appropriate tortoise machines are set. When the switch is turned back to the "normal" position, the tortoise machines all return to their "default" positions. Only the outbound leg of the yard is shown. The inbound leg is also wired but is much simpler in that each siding is connected directly to mainline.


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## gregc (Apr 25, 2015)

i'm impressed.

if i understand it correctly, the default toggle switch (right) connects the switch machine to -9V and provides -9V to all higher toggle switches. 

When you move a toggle switch to the left, you provide 9V to all the switch machines that need to switch position (reverse) either directly or thru diodes and break the -9V path to all higher toggle switches (and turnouts) 


so when T2 is selected, T2 and T1 are connected to 9V, but T3 and T4 (all other turnouts) are simply disconnected, not connected to either 9V or -9V.

some would argue you need to maintain pressure on the points (hand laid turnouts with sold point rails). But if that were an issue you could probably adjust points to favor the normal non-diverging position.

thanks for posting


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## gordo53 (Jul 28, 2019)

Yes, you have it exactly right. The spring on the tortoise machine maintains the pressure on the turnout. Thanks much for your interest and feedback.


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