Next electrical question: Arduino powered DC/DCC circuit breaking?

[John]

This won’t be popular, but trying to use both modes on a layout at one time is a recipe for disaster.  Quit trying to accommodate both modes simultaneously.  Do one or the other. If you must run DC then have a time period set aside for those runners, or don’t include crossovers that can cause the issue you’re trying to solve. 

Send the hate mail to @UPModeler

[kiwi_al]

Send the hate mail to @UPModeler

ROTFLMAO  Geez you did have to bring him up after all these years!!!

[peteski]

This won’t be popular, but trying to use both modes on a layout at one time is a recipe for disaster. 

Thanks for another voice of reason. I've been trying to (mostly unsuccessfully) make this point since this thread started.

Send hate mail to peteski! 

[jagged ben]

I blew out a dc power pack when I accidently connected it to a track with dcc power. I support this endevor.

What kind of power pack was that?  Just curious.  How long was it hooked up for?

[Lemosteam]

What about a logical solution:

Have the Arduino sense/monitor six things, three for each track:

DC
1: Power type DC or DCC?
2: Polarity
3: Voltage (current) whatever, lol (not sure if needed)

DCC
1: Power type DC or DCC?
2: Direction of all available power on the circuit
3: Voltage (current) whatever, lol (not sure if needed)

Monitor the crossover (both switches) for operational function, i.e. is it in working condition?

1: Operable? , i.e. is it in working condition?
2: Current position: Open for crossover or closed to crossover

Then develop a situational control for every condition, program the code, and use your electrical genius to make it work on that module.

I.e.
Both tracks DCC: crossover switch is available to use

Both tracks DC: crossover switch is available to use

Inner DCC outer DC vice-versa- disable crossover completely, I.e. prevent traffic from leaving a given track.

Crossover malfunction or manual turnout throw on one or the other: shut down

[Maletrain]

I agree that it is not a great idea to run DCC on one loop and DC on the other at the same time.

But, I also know that the reality of the situation is that there are people who want to do that, and the ad hoc nature of a T-Trak meet is such that somebody is likely to try it more than once, even if there has been some bad experiences with doing it.

And, crossovers in T-Trak will (mostly) be made with Kato turnouts, which have little mechanical sliders that change the turnout direction and the electrical paths inside the molded "ballast" of the track sections.  So, it is not possible to "lock" those turnouts electrically.  IF a module setup includes a crossover, then the modes for powering the loops need to be limited administratively to avoid any trouble with the potential use of the crossover, and we all know how well the rules are adhered to.

I am not sure what can happen with a DCC component circuit that is back-fed with DC. 

I have read a post by Robin Becker that the Tam Valley "Frog Juicers" will not be destroyed by DC power on the tracks, and will even work to open the circuit, but will NOT REVERSE a DC current.  So, presumably, 2 juicers used as a both-pole circuit breaker would not be damaged and could be a DC or DCC circuit breaker.  So, MAYBE you could power isolated, short track sections with the turnouts on each side of a crossover through something like that, which would at least open the circuits if the result was excess current through either power source. 

But, I still don't know what NOT excessive DC current can do to a DCC component.  Or vice versa.

[Lemosteam]

And, crossovers in T-Trak will (mostly) be made with Kato turnouts, which have little mechanical sliders that change the turnout direction and the electrical paths inside the molded "ballast" of the track sections.  So, it is not possible to "lock" those turnouts electrically.  IF a module setup includes a crossover, then the modes for powering the loops need to be limited administratively to avoid any trouble with the potential use of the crossover, and we all know how well the rules are adhered to.

Remove the sliders on crossovers only and force them to always be electrically thrown only (which could be controlled with the Arduino by simply disabling the circuit).  Just like with the old ATLAS solenoids, it was always best to wire them together so that both turnouts were thrown into the diverging direction to avoid derailments.

[Maletrain]

Remove the sliders on crossovers only and force them to always be electrically thrown only (which could be controlled with the Arduino by simply disabling the circuit).  Just like with the old ATLAS solenoids, it was always best to wire them together so that both turnouts were thrown into the diverging direction to avoid derailments.

I think there might be some push-back from people who own the modules if there is a rule requiring them to be physically disabled to suit an operating mode they may not agree with and will not see on most of their setups.

My current thinking is to have some sort of visible signal, such as an LED that is visible from any crossover location, that is only green if use of the crossover is permitted, and otherwise red.  Not perfectly reliable, but probably better adhered to than power supply setup guidelines.

[Lemosteam]

Fair, but I am not sure Ed is referring to use within the standard.  His other threads have been about his clubs.  Not sure, Ed?

[Maletrain]

I think Ed and I are considering slightly different off-standard situations.

In my case, I am NOT considering allowing DC on one loop and DCC on the other loop, but am considering allowing crossovers.  That would be enforced by my power supply switch board, as discussed in the other thread.  So, my only concern is that crossovers in DC mode where the two loops had different DC controllers might cause some problems, particularly if those DC controllers used pulse-width speed control instead of simple voltage level speed control.

Ed can speak (post) for himself, but he does seem to be considering having DC on one loop and DCC on the other.  I am somewhat interested in the potential for problems with that because my home test layout has an outer loop that I can power with DC or DCC, which is connected by a crossover to an inner loop that I only run with DCC.  My concern has been whether inadvertent bridging of the two loops with DC power could harm my DCC circuit breakers and reversers by back-feeding them with DC, while they are NOT powered with DCC.  So, that has me looking at things like the post by Robin Becker about the effects of DC on their DCC equipment.  I still need to check with the PSX people about the same issue.

[John]

What about a logical solution:

Have the Arduino sense/monitor six things, three for each track:

DC
1: Power type DC or DCC?
2: Polarity
3: Voltage (current) whatever, lol (not sure if needed)

DCC
1: Power type DC or DCC?
2: Direction of all available power on the circuit
3: Voltage (current) whatever, lol (not sure if needed)

Monitor the crossover (both switches) for operational function, i.e. is it in working condition?

1: Operable? , i.e. is it in working condition?
2: Current position: Open for crossover or closed to crossover

Then develop a situational control for every condition, program the code, and use your electrical genius to make it work on that module.

I.e.
Both tracks DCC: crossover switch is available to use

Both tracks DC: crossover switch is available to use

Inner DCC outer DC vice-versa- disable crossover completely, I.e. prevent traffic from leaving a given track.

Crossover malfunction or manual turnout throw on one or the other: shut down

That's actually a great idea if the users insist on using both at the same time .. sort of an interlocking ..

[Maletrain]

The trouble with this sort of interlocking is that it breaks down with the Kato turnouts being manually throwable and that causes internal electrical switching of the track power routing.  And it would be hard to even sense the position of a manually thrown Kato turnout without doing physical alterations of the turnout.  So, a full interlocking concept is unlikely to be feasible for a layout where different contributors with different backgrounds all provide modules.

Also, if there are 2 separate DC controllers used for the 2 loops, there is the issue about whether they are pulse width controlled or steady DC.  If they are both plain vanilla DC, then probably no serious damage  concerns, even with polarities not matched.  But, if they use pulse width, especially if it comes with some sort of feed-back, what is the effect of interconnecting the two controllers on the controllers themselves?  I don't know that is OK, so I intend to avoid it as much as I practically can.

I plan to NOT allow crossover use with DC unless the power for both loops comes from the same controller.  But, the only feasible way to do that I can think of is to have an LED indicator that is green when crossovers are "allowed" and red otherwise, and try to train users to look at that indicator before throwing a crossover. 

The way I would have the power input board configured, it would be possible for the situation with 2 DC controllers to be converted to having one controller provide power to both loops, while isolating the other controller, by throwing one electrical switch on the panel, which would result in the red "crossover approved" LED changing to green.  So, a crossover move with 2 DC controllers could still be executed by throwing one switch on the power panel, using the crossover and returning it to straight-through, and then throwing the power panel switch back to dual DC control. 

[jagged ben]

The trouble with this sort of interlocking is that it breaks down with the Kato turnouts being manually throwable and that causes internal electrical switching of the track power routing.

I don't see where you got the idea of locking out turnouts.  My suggested approach in reply #13 doesn't require that.  Kill power to the turnouts when DC is lined to go into DCC, or vice versa, if you prefer.  That's all. 

And it would be hard to even sense the position of a manually thrown Kato turnout without doing physical alterations of the turnout. 
...

No it wouldn't, because they are power routing.  Just measure voltage on the trailing point rails of the diverging route.  This is almost the easiest part.

[mmagliaro]

Arduino?

Perhaps this will be useful.  It tells whether the voltage connected at the input is AC or DC, and lights one or the other LED, and powers or drops out a relay.
And yes, this works, and yes, I have PCB layouts for it. 

Two of these and you know whether each track is DC or AC.

Now, what do you want to do with that information?

[Maletrain]

Jagged Ben,  I don't want to get into an argument, but I really don't see how you can electronically detect when a Kato turnout is manually thrown without at least soldering a wire to the diverging rail past the frog.  And, then that needs to be sensed for both DC and AC power against the other diverging rail, because we don't know in advance whether there will be DC or DCC on the straight-through path for a particular turnout.  At least there is already an available wire for the other rail.  And, those wires would need some sort of additional bus to take them to the interlocking mechanism location.  Or, a separate interlocking device would be needed for each crossover.

The problem as I see it is whether you can count on everybody with a module that has a crossover coming with those 2 additional wires soldered to the appropriate rails on their module.

I guess Ed's situation, a club that can set its own standards, could make that happen.

For my situation, where I am trying to attract newbies with an opportunity that involves the minimum of fuss, that is not an attractive option.  Nor is having to provide programmed arduinos and power relays for the modules that show up with crossovers.

T-Trak is intended to provide a simple, entry level experience.  But, at its most basic, it just runs 2 trains in separate circles.  To make it more interesting, you need to violate the basic standard to some extent.  But, that is a slippery slope.