One word- relays

Does NCE have a “black box” that will turn a light on/off or one with a momentary impulse intended to throw switches? Digitrax, Marklin/Trix, Bachmann have such a device. I would think NCE would have something similar.

Further, I thought I read on this forum, many years ago, that DCC doesn’t work well with O gauge switches in general due to the electrical path DCC has to taken in the switch.

Steve

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THANKS for the two replies to this question.

@Vernon Barry posted:

One word- relays

• ==> I don't see how a relay would help here ??  Please elaborate if you have time to.

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@RideTheRails posted:

Does NCE have a “black box” that will turn a light on/off or one with a momentary impulse intended to throw switches? Digitrax, Marklin/Trix, Bachmann have such a device. I would think NCE would have something similar.

• ==> NCE in fact, DOES have several "black boxes" to control turnout motors.
• ==> But that signal is not intended to "mix" with the track signal (as is the case with these 3-rail turnouts).

Further, I thought I read on this forum, many years ago, that DCC doesn’t work well with O gauge switches in general due to the electrical path DCC has to take in the switch.

Steve

• ==> I think this is the problem, the turnout motor and the rails are part of the same "electrical path" you mentioned.

• ==> I tried to find that post you mentioned, but could not find it.

• When DCS is used, the "black box" is the AIU -- which is designed to "play" with the TIU.
• But MTH hasn't designed an equivalent "black box" to use with DCC, and I'm sure they're NOT interested in doing so.
  

Sorry, not trying to start something- was just trying to nudge you into the answer. I figured if you wired up all that and seemed to know a little about DCC, and was hoping you read the manual.

Let's dive into the first part: 2 different things- although they can share- 2 important concepts:

Controlling a switch using DCC and a decoder for that control system.

Powering a switch- does NOT need to be tied to the control system- and some decoder PCBs might allow for a power source, or the concept of using a relay to isolate the high current and voltage power required for the switch motor coils- from your DCC control board- again using something easy like a relay.

Example realtrax O-42 manual https://mthtrains.com/sites/de...ction/40as19639i.pdf

OK, so now we know that we can provide a completely separate 14-16V AC supply voltage that is NOT connected to the center rail of the track. In doing so- we RETAIN the anti-derailing sensing function of the switch, it is always powered regardless of DCC power on or not on the track.

Note- black wire- AKA common- is connected to outside rail. This is OK, we have at least partial (center rail not connected) to any DCC track power.

I'll separate control subsystem into a second post.

Again, in the previous post we covered separate auxilary power and a transformer for powering the switch and how to ISOLATE- by removing the jumper- the switch motor section and power and lights from DCC track power. Again- remove the jumper on all realtrax switches. Then wire a separate power source just for switches.

Control:

You said this earlier- NCE Corp. makes the Switch-Kat (for Kato & LGB), Switch-It (for Tortoise), and Snap-It (for American Flyer & S Helper) for controlling various types of turnout motors.

Just some discussion on why different control modules are made and what they are intended for. The realtrax switches are twin coil motors. A few brands have twin coil motors- Atlas being another one. The difference is MTH added extra circuitry and switches inside the motor to disable a coil once the switch has fully moved one direction or the other. This added circuitry helps to protect the coils from overheating if the activation or control circuit rather than a limited pulse or time of commanding the switch to switch- is more of a constant on one direction or the other (momentary VS toggle- basically). Because of this built in feature of self disabling the coil for a direction once in that position- we can treat this as a much simpler motor without worry. In other words- the very specific protection of something like a capacitive discharge switch control like "Snap-It" is not strictly required and won't help a lot with this switch.

So, of NCE decoder choices, QSnap seems IMO to meet some needs and features we might want given the situation. https://ncedcc.zendesk.com/hc/...Coil-Switch-Machines

It's a twin coil machine- just no capacitive discharge and can be separately powered and thus semi isolated from direct DCC track power.

Last a snippet from the manual

DC power option
A DC power connector is provided if you wish to use external power to run the decoder
and switch machines. This will enable the Switch8-Mk2 will ride through DCC track
shorts without power interruptions. Use a power supply providing between 9 and
15VDC with a 2.5/5.5mm plug, center positive (The NCE P114 is a good option here).
The power supply should be able to supply at least 200mA. If you connect an external
supply move the DC/DCC Power Select Switch to the DC position.
The DC voltage for the switch machines will be approximately 2 volts less than twice the
DC volts. Example : 12Vdc will yield about ((2 x 12) - 2) or 22 volts to the switch
machine.

OK, so here is the part I'm a little less sure about and may require the relays as an extra layer of isolation- both for current reasons as I do not know the current of the reatrax switch motor coils- and part 2- the anti derailing function most likely also is seen on the control wires to common. This poses NO PROBLEM if we use additional relay isolation- the relay contacts simply short one control direction lead of the switch to common- and so it won't matter. The controller- something like a QSnap or equivalent- can drive the relay coils just like a twin coil motor.

I don't know if this is additional wiring is absolutely needed- but I can say in O scale with derailments and other things- I think a good idea to protect your electronics.

@Vernon Barry posted:

Sorry, not trying to start something- was just trying to nudge you into the answer. I figured if you wired up all that and seemed to know a little about DCC, and was hoping you read the manual.

(1) Vernon: THANKS for putting together all this information.

(2) That looks like a lot of WORK that you did, to create those drawings and accompanying text ??

(3) The information you wrote is very INFORMATIVE.

HOWEVER: ~~~~~~~~~

• At this point, I'm probably "in over my head" with respect to electrical knowledge needed to make these MTH turnouts work with DCC track power.
• I'd like to try to get you or one of the other smart electrical guys to try this sometime with the MTH turnout -- but myself I'm going to "back off".

1. Future Approach ~~~~~~~~~

• My future approach -- if I ever do this -- would probably be to get turnouts like Ross or similar -- where the turnout motor is NOT connected electrically to the track.
• 
  * Then I should be able to use the same "established" hardware and methods I have used in the past -- to control LGB and Kato turnouts.
• I set up these Automatic Control "experiments" and videos with the hope that OTHERS in the future might use the information to repeat it themselves -- so I want to try to make it no more complicated than necessary.

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2. FYI: Previous Auxiliary Power to Turnouts

Following below as an FYI, is what I've done previously with using AC track power and DCC control:

Fig 1 - AC Track Power (2021 Video #833)

• Fig. 1 above shows a hookup from 2021 --where we used an NCE "Dual Relay" to control an MTH turnout, where the track power was AC, and we were using auxiliary input (with the jumper removed) to provide constant power to the turnout.
• In this case the "common" (-) for both the track and turnout were connected to the 'A' terminal of the old Lionel transformer that we used.

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Fig 2 - 2021 - AC Track Power (complete drawing)

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Fig 2 above shows the entire control board.

• We were controlling 2 Bachmann Chuggington conventional locos by turning blocks in the track on and off.
• So we had relays 'R1' and 'R2' controlling the track blocks, Relay 'R3' controlling the 'diverging' turnout, and Relay 'R4' controlling a red/green "status light" that told the kids when they could push the 'Start' button again.  
• The NCE "Mini-Panel" controlled all these relays automatically.

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Fig 3 - from 2021 Video #833

This setup is shown in the 3-part Video #833, titled "'Chuggington Central RR' O-Ga. Public Display, DCC Relay Control of 2 Non-DCC Locos".

Part 2 at the about the 7:30 point ( https://youtu.be/kHlvMf2qFOo?s...oNorbUAXxU&t=451 ) shows the 5 terminals-- and using a wire to simulate how the relay controls the turnout.

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3. Possible Hookup For DCC Track Power (Not Sure It'll Work or Not)

Fig 4 - Sketch for DCC Track Power

Fig. 4 shows a modification of that same drawing --using the same NCE "Dual Relay" to control the turnout motor -- using the same NCE 'Dual Relay' -- but this time with DCC track power.

• I think this is sort of similiar to what you (Vernon) were showing in your last sketch ??
• In this case, the outer rails ("common" (-) would be connected to both the Lionel AC pack and the NCE DCC command station -- see the terminal block in the lower right of the sketch.
• I'm not sure if this would work, or would damage one or both power units.
• Here's where someone more knowledgeable than me, could probably proceed more intelligently.

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As I mentioned above, I'm inclined to "play it safe" and proceed with a different turnout that has the turnout motor completely ISOLATED from the track rails.

But it would still be useful to know --  if this can be done with the MTH turnouts.

I'm hoping someone SMARTER than me with electricity -- will try this sometime.