controlling kato turnouts with several switches

[alain10025]

Hello,

 

As my unitrack layout is getting a bit complex, I decided to drop the "one turnout / one switch" idea to control several turnouts at a time so that one switch now defines a given pathway for a train, thus controlling potentially a fairly large number of turnouts (say from 4 to 10 typically). 

 

First, it seems the Kato power supply is a bit short in power and I find that switching simultaneously 6 or more turnouts leads to a non negligble speed drop (which I could already observe with the double crossover that includes 4 turnouts) of trains running on the layout. I intend to get a separate DC supply, probably 12V / 5A to avoid any issue.

 

The reason I am writing this post is because when I use my switches as described above, I find myself in a situation where some turnouts will be controlled by several switches. See, for instance, the example below where I consider two switches : one for the red route and one for the yellow route. Both routes start from the same turnout.

 

Assuming both the yellow and the red switches are connected to the same power supply, when I activate one switch, power will go through the turnouts but also through the yellow switch and vice versa. I found that this seems to short circuit my power supply (not always though). In order to avoid the power coming back through the other switch, I initially thought to use rectifier diodes but - I am quite new at this, I may be missing something... - the inversion of polarity at the exit of the switch seems to make this solution unfeasible.

 

So here is my question : is there any way to control one turnout with several switches connected to the same power supply ?

 

Thank you !

 

Alain

 

 

Edited Monday at 01:24 AM by alain10025
typo

[inobu]

Alian,

 

It is about the applied voltage to the switch themselves. The Kato switches are called snap switches. The require 12v momentarily

which creates a magnetic field that throws the switch. It need a polarity switch to push the magnetic field the other direction.

 

When you tie all the switches together and throw them in unison then current demand is a multiple of each switch. 
 

You are not seeing a short circuit but an overload of current. Its typically called an "in rush of current"

 

What you are wanting to do is called Switch Routing. This is when one control point issues or actuate a series of switches to

create a path or route for the train to travel.

 

That is a nice yard you have and bringing electronics and computer control is the way to go.

 

Look into DCC-EX as it is opensource and used Arduino's as its main component. I'm not telling you to go DCC but

use the switching aspect of DCC-EX for your DC layout.

 

You can use DCC-EX to create a PWM DC controller that will replace your Kato transformer. I thin that is the way to go.

 

Inobu

 

 

 

 

 

[cteno4]

Alain,

 

the old BCD capacitor discharge circuit haas some options to do multiple switch firing. George outlined some ideas in one fo his docs. Might want to take a look at them too. Simple circuit to fire a switch with prefect pulse, but gets a bit crazier when you get into the multiple firings.

 

Cheers

 

jeff

[dotzen]

EX-Rail, the route automation function of DCC-EX mentioned by inobu, is very powerful. You don't have to use DCC anywhere on your layout to take advantage of this. You do need some form of driver that can be computer controlled for each switch. I have some from a local Australian supplier that control 8 Kato switches per board for $70AUD, there are many other options out there. The basic operation is that you can define each of switches on your layout, then create a route that either throws or closes each switch to the desired state, and you can then call each route to activate it. This can be done from a phone app, or you can even define a button and use the physical button to activate the route. Signals and other accessories can also be defined and set in the same manner. There is a bit of a learning curve to Ex-Rail but there is a very comprehensive tutorial on the DCC-EX website to guide you through the basics.

Regardless of how you proceed with automating multiple switches, powering the switch controllers from a separate supply to the loco is vital.

Edited Monday at 09:57 PM by dotzen

[MrLinderman]

1 hour ago, dotzen said:

EX-Rail, the route automation function of DCC-EX mentioned by inobu, is very powerful. You don't have to use DCC anywhere on your layout to take advantage of this. You do need some form of driver that can be computer controlled for each switch. I have some from a local Australian supplier that control 8 Kato switches per board for $70AUD, there are many other options out there. The basic operation is that you can define each of switches on your layout, then create a route that either throws or closes each switch to the desired state, and you can then call each route to activate it. This can be done from a phone app, or you can even define a button and use the physical button to activate the route. Signals and other accessories can also be defined and set in the same manner. There is a bit of a learning curve to Ex-Rail but there is a very comprehensive tutorial on the DCC-EX website to guide you through the basics.

Regardless of how you proceed with automating multiple switches, powering the switch controllers from a separate supply to the loco is vital.

 

Hi Dotzen, is that switch driver from simplyrail? 

[alain10025]

Thank you @inobu, @cteno4 and @dotzen for all your comments ! I get that using a more versatile computer / Arduino based solution would be ideal and surely very versatile. I will have a look at DCC-EX, their website is very detailed (and it runs on Linux systems, always a plus !). 

 

In any case, I will use a separate power supply to prevent any perturbation for running trains.

 

Just a comment with respect to @inobu said, I think you are right that an "in rush of current" may occur but I am not completely certain this is what I observe with my Kato power supply since I can reproduce consistently the issue with certain switches but not with others... In any case, uisng a different power source will solve that issue.

 

Thanks again !

 

Alain

[cteno4]

@alain10025,

 

How have you wired your points up? Could be in the cable and connections used you see the variations. Doesnt take much to loosen a tad of power pulse to make the switches not fire as well. Also have you swapped controller switches between good point and bad point as the controller switches are very mechanical beasts with strip just snapping past a contact to make the pulse and that can be very variable.

 

jeff

[dotzen]

22 hours ago, MrLinderman said:

 

Hi Dotzen, is that switch driver from simplyrail? 

No, the ones I have are from Rosscoe Train, https://rosscoe.com/shop/index.php?main_page=product_info&cPath=1&products_id=8

These are designed for Kato or similar that reverse the polarity across the solenoid. I even use them to drive dual solenoid Fleischmann points as I know that the design can manage this without burning anything out.

Simplyrail are great for servo controlled stuff.

[MrLinderman]

58 minutes ago, dotzen said:

No, the ones I have are from Rosscoe Train, https://rosscoe.com/shop/index.php?main_page=product_info&cPath=1&products_id=8

These are designed for Kato or similar that reverse the polarity across the solenoid. I even use them to drive dual solenoid Fleischmann points as I know that the design can manage this without burning anything out.

Simplyrail are great for servo controlled stuff.

 

Thanks Dotzen, link saved. looks like a great addition for my upcoming DCC setup

 

I'm assuming these would also work fine with Tomix switches?

Edited Tuesday at 10:45 PM by MrLinderman

[dotzen]

Yes, any point motor that uses a momentary activated solenoid and reverses polarity to switch back.

These use small H-Bridge drivers to provide the switching, and a capacitor discharge to provide the 'oomph' to energise the coil.

There's nothing inherently wrong with the old BCD circuit, but times have moved on and small H-bridges are very cheap and versatile.