Kato automatic DC reversing loop

[tossedman]

Has anyone had any success creating an automatic reversing loop on a DC layout using Kato switches? If so, what brand reverser did you use?

 

Thanks,

 

Todd

[katoftw]

Why not make a block and use the Kato reverse switch?

[kvp]

I think the confusion might be that the original question if for using a kato turnout, without any manual switches. So the reverser has to throw the turnout and switch the polarity.

 

I remember that there was an old style automatic crossing gate for Kato that used track contacts. The expansion set had two extra contact rails. These can be used to sense the train right before the turnout. The signal has to be amplified from TTL level to relay drive level (with a transistor for each sensor), then a 3 circuit bistable relay can be thrown with it. One circuit of the relay can drive a capacitor discharge circuit to throw the turnout, the other two can be used to reverse the voltage polarity on the mainline. Using 4 sensors connected in pairs (the transistors allow this) and using a 4 circuit relay allows the throwing of 2 turnouts on two loops. Don't forget to isolate both rails on both legs of both turnouts and feed both loops directly and the main through the reverser relay.

 

The circuit above works with any train sensor, be it magnetic, optical or current consumption detector. The only rule is that each train must completly fit between the two sensors, but if the sensors are mounted just after the turnout, then this gives maximal train size for a given loop. Imho the optical sensor crossing gate expansion sensor is still manufactured by kato. But it's possible to get any point based train sensor that can drive a relay and use that. The relay has to be bistable, 4 ciruits, 4x2 inputs and able to handle 2 ampers. (and ideally it should run from the same voltage as the sensors)

 

ps: For other track systems, like maerklin z or berliner tt bahn, the track sensors give direct output power for the same brand relays and turnouts, so you can just wire them together (each sensor to one of the relay coils and one of the turnout coils). For tomix tcs, you still need amplifiers to throw the turnouts, but the mainline polarization is done by the turnouts.

[cteno4]

circuitron has some auto reverses that you can add addon boards to that might also be able to throw the points as well. One way is to use sensors and their other used power draw for detection. I've used their auto reversers for point to point situations and they work decently. Their instructions although complete at times can be hard to follow. Little fiddly to adjust up on the sensors. Did have one club members here that I inatalled on on his layout and like 6 months later the board failed.mthey did replace it free of charge.

 

Their point control stuff may be double coil ac, can't remember.

 

http://www.circuitron.com

 

https://www.azatrax.com/reverse-loop-system-2.html

 

http://www.bakatronics.com/shop/search.aspx?search=Aar3

 

Cheers

 

Jeff

[kvp]

Imho from the three, this seems to be the winner:

http://www.azatrax.com/reverse-loop-system-2.html

 

For Kato turnouts, you can use a single 12V supply (the top one), skip the blue wire with the bottom supply (you might have to swap K1-K2 at the relays) and use two double pole double throw relays or a single 12V quad pole double throw. Use the second relay (or the 3rd and 4th poles) to select between 12V (red) and gnd (black) and add one 1000 uF capacitor in series with each Kato switch coil and tie the other ends to gnd (black) and you are ready. If you are buying from the site, you don't need the two tortoise switch machines but need a 2nd dpdt relay.

 

ps: total cost: $36.50+$9.15*2+$9.50=$64.30 (you don't really need the diodes with the above modification, just check the relay polarities before connecting)

Edited March 1, 2015 by kvp

[tossedman]

Thanks for the feedback folks. KVP, I seem to have come to the same conclusion as you. I emailed Azatrax and asked. The reply from John was as follows:

"Thank you for visiting our website, Todd.  Yes, the double reverse loop can be used with Kato's single coil switch machines.  See:

http://www.azatrax.com/reverse-loop-system-2.html#snap-switch

The first diagram shows Atlas type twin-coil switch machines.  Scroll down to the next diagram so see the single coil Kato switches.

The Azatrax products you'll need:
One MRD2 dual detector/turnout control
One LARY-DC latching relay

Installation of the infrared sensors can be done by drilling 3/16-inch holes in the track roadbed, or the sensors can be placed beside the track and disguised with scenery or structures.

You'll also need the plastic rail joiners to make the insulated rail joints at the eight places shown on the diagram.  These you can get from the place that sells the Kato track."

 

I'm not sure if I'm going to try this double reversing loop yet but it's good to know that I am able to use Kato points.

 

Thanks again,

 

Todd 

[kvp]

I'm not really sure if you can use the Kato turnouts without an extra dpdt relay and the capacitors. The LGB switches have an end switch, but the Kato ones don't and will burn out if keept powered. The modification i wrote takes care of that and you only need a single (cheaper) 12V DC power pack and the cheaper non latching dpdt relays (but actually two of them).

[tossedman]

Good point kvp. I shall investigate further.

[tossedman]

Well, I contacted Azatrak and was told the MRD2 circuit board has two 'Mode' switches. The installation guide tells you to install and adjust the sensors first, before connecting switch machines, with the Mode switches set to 'N' and 'S'.

 

Once the sensors are known to work properly, set the Mode switches to 'TO' ('turnout') and 'S' ('snap'). This setting will energize the switch machines only momentarily to avoid burnout. If the Mode switch is set differently then switch machine burnout can happen, so check the Mode switch before connecting switch machine power.

 

So, looks like it should work with Kato turnouts.

 

Todd

[gavino200]

On 3/1/2015 at 8:46 PM, tossedman said:

Well, I contacted Azatrak and was told the MRD2 circuit board has two 'Mode' switches. The installation guide tells you to install and adjust the sensors first, before connecting switch machines, with the Mode switches set to 'N' and 'S'.

 

Once the sensors are known to work properly, set the Mode switches to 'TO' ('turnout') and 'S' ('snap'). This setting will energize the switch machines only momentarily to avoid burnout. If the Mode switch is set differently then switch machine burnout can happen, so check the Mode switch before connecting switch machine power.

 

So, looks like it should work with Kato turnouts.

 

Todd

 

 

Did you ever get around to trying this? How did it work? Would you choose this system again?

 

Anyone know of any other systems that have come out since this thread went into hibernation?

 

I'm planning to keep the Tram line DC. I may use a DCC decoder to supply DC power to the line. But I don't suspect this would make any difference to how the reversing loop would function.

 

My options as I can see them are:

 

1. A reversing loop on each end. Not sure if I can have stops as well with a DC system.

2. A junction at each end to alternate trams. One arrives and one leaves. At both ends.

3. A simple straight line where a single tram would just arrive, stop, reverse, and go back the way it came.

 

It would be nice to  be able to override automation and run manually. But that's not essential. I think the tram would be cool to have running in the background but might be a bit boring to actually run. 

 

Anyone have any experience or opinions?

Edited February 11, 2018 by gavino200

[tossedman]

You know, I bought it but it's still sitting on the shelf. Haven't got far enough on building a layout to install it. One day. Hopefully sooner rather than later.

[kvp]

On 2/11/2018 at 11:28 PM, gavino200 said:

1. A reversing loop on each end. Not sure if I can have stops as well with a DC system.

Yes, actually if you control the loops separately without interfering with the powre feed, then you can use the Tomix automatic control unit (the old one) to do automatic stops with slow down and speed up. It also has a manual mode, where you can use any controller to drive your tram. (in automatic mode, the controller just sets the top speed so you still have manual control, but the automatic stops will override that) You can even place stops inside the two reversing loops.

 

Imho the old Tomix unit could do both variants of the point to point automation you mentioned besides the stops between the loops operation.