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 February 17 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 February 17 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 February 18 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.

[alain10025]

Hello,

 

I thought I would come back here to give a little update on my situation... So, after trying hard to find a solution to isolate two DC sources one from another when they are both connected to the same kato turnout, I realized that this seems impossible with diodes due to the way polarity is reversed with the switch... 

 

I think the solution suggested by @inobu is the way to go : either a DCC-EX control station or, maybe a more generic arduino-based solution (I believe the main difference is that DCC-EX comes with a dedicated piece of software and android and ios apps...). 

 

In terms of arduino, I have zero knowledge. It seems there are some tutorials here and there but I was wondering if you know of any resource or tutorial explaining how to control 15 to 20 turnouts. What I have in mind is a setup where all the turnouts are connected to an arduino (through H-bridges or relay channels boards, this is still unclear to me)...

 

Thank you !

 

Alain

[inobu]

Alain,

 

I have been trying to find the best recommendation based on what you have stated. Here's what I think.

First lets go over you initial attempt. This is what you initially tried with the Diode. I think this is the device

you were trying to build. This is a Digikeijs DR4101. This board will flip flop the polarity based on Diodes.

It takes two input voltage inputs and flips the output on the wire. Which is what the Kato Switched need. 

You can find these on ebay and reverse engineer them and build yourself.

 

Even if you do this you still need a device to trigger the output voltage to drive the switch condition.

Then the Software to manage it.

 

This brings us to DCC-EX

 

DCC-EX

 

First lets understand the dynamics of the Kato Switches again. The switches need 12v to

operate. +12v one direction and -12v the other. DCC-EX provides a solution call a Motor Driver.

Its a L293D. This comes in a chip form or a complete board. We will look at the Complete board form first.

 

This board can control 2 different Kato Switches

 

 

 

From a robotic usage the board is created 

to drive motors on a robot be it wheel or arm. The IN pins are

the input pins from a MCU. We will use the Arduino for example. The output of

the Arduino GPIO pins are low voltage and low current signal called Logic Level output.

The Right side of the board is the Logic Level side/Arduino

The  IN1 and IN2 controls the direction of one motor and IN3 and IN4 controls the other.

 

The left side is the High Level side. This is where you provide the 12v for the Kato switch

to operate. You see the A- and A+ that is how the direction of the motor is operated.

The IC chip is what operates and responds to the Arduino.

 

Arduino and Single L293D

 

Here we have the single chip on a bread board connected to the switches.

This is basically the same connection as the completed board has. 

The problem is the limitation of the GPIO pins.

 

Below is a expansion board that increases the number of GPIO pins.

It used a I2C bus that the Arduino uses to increase the number of GPIO

Pins.

 

With the extension board and L293D boards you can cover your 20 turnouts.

 

So DCC-EX may be the way to go for you. Learning the Arduino isn't that hard.

Its worth while to learn as well.

 

Inobu

[alain10025]

Thank you very much @inobu for this detailed and clear answer. I am very interested in your suggestion to use a L293D board (or chip) as some of the tutorials I found were going for a L298P (such as this tutorial for instance) or a L298N when 2 turnouts are considered (such as this tutorial).

 

A quick look online showed me that one of the differences between the L293D and L298P seem to be the intensity of the current (max 600 mA for the L293D, versus max 2 A for the L298P) per channel. I believe this means that the L293D cannot receive more than one turnout per channel (I do not remember where I read this, but I believe one turnout can require up to 500 or 600 mA).

 

Would you advise against using a L298P with up to 2 or 3 Kato turnouts per channel ? It would seem to be an interesting option to me when some turnouts are activated in pairs (such as when two turnouts face each other from a track to another).

 

One last question if I may, I am having a hard time findig the expansion board you show for Arduino. I could only find something like this, Would you have a reference for such an extension board ?

 

Thank you again !

 

Alain

[inobu]

Those tutorials are repurposing the old driver board used in the old DCC setup. What I posted is the same type of board not made

for an Arduino.  Don't get caught up with what he is using. Pay attention to the device itself. Motor driver board. Look here

Because its a snap switch the power is momentary. So the current switch will be just a pulse. These are stepper motor drivers

but look at the price.

 

The link that you provided is for the Arduino UNO that is a smaller Arduino. The image I posted is for the Arduino Mega

its a faster Arduino.

 

This is how I see it. You have no other choice but to get one. What else are you going to do or use?

What you can do with it is going to benefit you 10 fold. Once you learn about the I2C bus and the IO ports

you can control just about anything.

 

This is what you want anyway.     Changing a Motor Driver Output to DC

 

Inobu

 

 

[alain10025]

@inobu, Excellent, thank you again !

 

Alain

[dotzen]

If you are considering DCC-EX there are a number of options depending on your skill level. See the DCC-EX web site about Conductor, Tinkerer, Engineer.

You can buy a DCC-EX CSB1 which will come pre-loaded with the DCC-EX control software, a display, and a power supply, and has two outputs that can be used for DCC or DC control. This is an all-in-one unit specifically designed to be simple to use. You can write automation scripts and load them to this unit via the USB interface and the EX-Installer app from you computer.

If you are comfortable with tinkering about with electronics, then you can build your own command station with an Arduino Mega, or preferably an STMicro Nucleo board. ST are one of the largest micro-controller manufacturers in the world and their Nucleo dev boards are exceptionally well made, more powerful than the Arduino's, and cheaper than the Arduino's. You use the same software as the CSB1 (there is only one version of software, it works on all platforms and has all functions), can add automation scripts, and interface with lots of sensors.

All of the software is free Open Source, is very well supported, and provides functions that commercial DCC systems do not.

If you are really keen you can of course develop your own system. I was already heading down this path but the DCC-EX team are so far ahead of me that i dropped everything that I was doing and jumped ship. I'm using DCC-EX to run a DCC layout with some simple automation, and also to run a DC layout with automation.  It is the best system I have seen.