Running both DCC & DC locos on the same layout.

[CRL]

I guess if you have to fry a loco, it’s cheaper to fry the DC one.

The prototype inspiration for my layout is the Clifton, AZ branchline off the UP at Lordsburg, NM. Most of that line was originally a narrow gauge line, so it has sharp curves and steep grades for a standard gauge line. Looks like I need to bite the bullet and dump my DC six axle locos at a minimum since the prototype uses exclusively 4 axle locos.

On the DCC part of the layout, which will be most of the layout, I plan on using the Digikeijs command station with the Digikeijs DR4088LN’s for block detection. They have a smart reverse loop module available that looks capable. All these use Loconet to communicate. They also offer servo controllers for turnouts, but I think I like the Tam Valley servo controllers better... and they’re cheaper. One of the Tam Valley controllers has a locking feature that might be useful at the DC / DCC junction point.

[C855B]

Can't speak for other systems, but one of the things that brought me over to Digitrax back in my N scale days is that at least back in 2005, it was the only system I knew of that allowed for simultaneous operation of DC and DCC locomotives. ...

"0000" is still allowed for locos without decoders, but the current firmware does have a lockout "CV" that may even be in the locked position by default. It's good for single operators, but lousy for multiples. The bit-stretching for DC occupies so much digital bandwidth you lose control of the DCC locos at times. The feature might not (don't know either way) be available in the latest "Zephyr" combo control station/throttle; it wasn't in the older models like the DCS50 and 51.

And like Ed said, it's not something you want to use for a long operating session. The PCM square wave causes the motors to heat up.

Oh - no adjacent DCC-DC blocks. Bad juju. Crossing the boundary is known to let the magic smoke out of decoders. Your LOTO idea still has the problem of bridging should you accidentally overrun the block. If you did that with a sub-block that goes neutral for the opposite circuit, it might help, but, say, if you ran m.u., other locos may push through anyway.

[CRL]

I was envisioning using the Tam Valley servo controller with the lock-out feature to control the turnout leading to the DC branchline or industrial switching area. When the switch is set to the mainline, there is no access to the DC area. When the switch is thrown to the diverging line which is restricted access to the mine only and is locked out to the mainline crew. Basically, I think this could be controlled using an interlock style feature tied to the operation of the servo controlled turnouts from the mainline and the mine to the interchange being slaved together.

Imagine a DC industrial switch engine for, say a mine or quarry, brings in “empty” hoppers from the interchange track. That switcher only needs DC power to extend far enough into the interchange track to couple to cars left there by the mainline local. The rest of the interchange could be dead. The mainline local needs access only to the interchange, not the mine trackage, which is too decrepit to support it anyway 😉. If the mainline diverging route is opened, the mine diverging lead closes. If the mine diverging lead opens, the mainline diverging route is closed.

[Dave V]

"0000" is still allowed for locos without decoders, but the current firmware does have a lockout "CV" that may even be in the locked position by default. It's good for single operators, but lousy for multiples. The bit-stretching for DC occupies so much digital bandwidth you lose control of the DCC locos at times. The feature might not (don't know either way) be available in the latest "Zephyr" combo control station/throttle; it wasn't in the older models like the DCS50 and 51.

And like Ed said, it's not something you want to use for a long operating session. The PCM square wave causes the motors to heat up.

Oh - no adjacent DCC-DC blocks. Bad juju. Crossing the boundary is known to let the magic smoke out of decoders. Your LOTO idea still has the problem of bridging should you accidentally overrun the block. If you did that with a sub-block that goes neutral for the opposite circuit, it might help, but, say, if you ran m.u., other locos may push through anyway.

I'd only ever done that with an old DB150 and never had a problem losing a DCC engine while double-heading analogs on my old Pennsy.  I have a DSC52 now, but currently all my shiznit is DCC so I'm not in a position to test whether the DSC52 is up to task.

Admittedly I never had to run more than two (and A/B lashup) DC engines at once on the PRR, and my RGS ops are even less frenzied, so I'd still be comfortable sending a DC engine out onto the line at "0000" against DCC traffic.  But I've never tried to do ops on the scale that you have.

The DC motor "whine" on Digitrax is a bit annoying...but I've never had any damage issues with the DC locomotives I used to run for hours at shows with my DCC engines on Digitrax.  I understand the hesitation to do it for prolonged periods, but my locos suffered no ill effects.  Eventually I was able to convert (or have a professional convert) them all to DCC, including a pair of FA/Bs that the great @wm3798 milled the frames out for me for and hardwired in the decoders.

[peteski]

This.

Digitrax lets you run both. DC operation isn't perfect, and you may not want to do it for long periods of time, but it works.

Even the latest coomand stations?  I'm surprised, but then again, we are talkign about Digitrax.

[peteski]

The DC motor "whine" on Digitrax is a bit annoying...but I've never had any damage issues with the DC locomotives I used to run for hours at shows with my DCC engines on Digitrax.  I understand the hesitation to do it for prolonged periods, but my locos suffered no ill effects.

Most conventional motors (with iron-core rotors) will heat up (even sitting still), but survive. But the DC operation on DCC is murder on coreless motors.  Even sitting still, motors are constantly under pulses of full DCC voltage that switches polarity many times a second.  That causes the armature to shake back and forth under full track voltage.  That vibration causes the whine sound, and those full voltage pulses create the heat in the windings.

[peteski]

Unless maybe I am dumb or unlucky enough to run a DCC engine from the yard onto the dead inner loop at the same time as I run a DC powered loco from the outer loop onto the dead inner loop.

Of all the people I know, you should know that statistically accidents can *AND WILL* happen. I would be strongly against and DC/DCC setup what would leave even the slightest remote possibility of those 2 power systems getting connected.  But that's me.

[Steveruger45]

I’m of the same mind Pete.  My layout had (as per my earlier post) DPDT switch to either select dcc or dc for the entire layout.  That switch is  long ago now removed as layout is run dcc only.

[Dave V]

Does the OP plan to eventually convert the DC locos to DCC at some future time (as money and time permit)?

I feel like that would inform the level of effort on the front end here.  Cost/benefit analysis type thing.

For me the Digitrax "trick" was right on the money because I'd always planned to go 100% DCC eventually as fast as time and money permitted...drop-ins into DCC-ready first with the old-school engines last.

[CRL]

@Dave V - Yes, the plan is to start with the drop in conversations and then convert as many of the remaining locos as time, money, eyesight & dexterity allow. The process could be expedited if a cure is found for anal retentive syndrome & OCD (or CDO as a friend says).

[peteski]

The process could be expedited if a cure is found for anal retentive syndrome & OCD (or CDO as a friend says).

Ah, them dyslexic friends? 

[CRL]

Ah, them dyslexic friends? 

Nope... just so OCD that she felt better with the letters in alpha order. 😉

[djconway]

When I started out in DCC, I had a layout with DPDT controlled block wiring.  To run DC or DCC I replaced one throttle/power supply with the DCC system (cab A) and kept the DC in cab b.  Worked out fairly well, ran that way for over 10 years - no magic smoke released, no fried DC motors.

[CRL]

One of my objectives on the layout is to take advantage of the somewhat simpler DCC wiring for the majority of the layout and only have the small DC sections isolated & controlled primarily using the power routing capability of the Peco turnouts. I’ve done this successfully before without any problems and know all the tricks to keeping them working. Number one is keeping all the turnouts accessible for occasional cleaning of the points. The one turnout that is hardest to reach is always the problem child.

[nstars]

Lenz did manufacture the LT100 module for just this situation. It would disconnect the DC power in case a short circuit was detected. Unfortunately Lenz stopped producing the LT100 years ago. You may still find it on Ebay.

Marc