Topics

Dual Mode? DCC/DC


Duff & Polly M
 

I am sorry if this has been asked before, or if this question should go elsewhere.
I currently operate DC, mainly because of the number of locomotives that will need work.  I do have a few locomotives that are DCC Ready.
A club I am joining is DCC.  I am thinking I would like to equip one or two of my DCC Ready locomotives with decoders, so they can run at the club.  However, I would also like to use them also at home on my DC layout.

I have heard something about dual mode decoders that can automatically determine whether DC or DCC is available.  If these do what I think they do, are available, and not too too expensive, I am inclined towards this solution.

Are there negatives to this approach, and.or recommended methods?

Thank you.


Greg Harter
 

Just for info:  Our club, in Columbus, Indiana, is over 25 years old, and has been running both DC and DCC on the same layout for over 20 years.  We use DCC detector boards, which we designed and built, that preclude a loco going from a DC track to a DCC track, or vice versa.  We have four mainlines, several crossovers and a couple of reversing loops, If the current on two specific mainlines isn't the same (DC or DCC), the crossovers will not operate, and/or the isolated track section between those two mainlines will not receive any current of either type.  We have never had an incident where this did not work, and have not had an incident involved any damage to a loco.  

We planned this originally because we had several members who wanted to run DC and several who wanted to run DCC.  

We did a clinic at the 2016 NMRA in Indianapolis on how this operates.  

Dual mode decoders are okay, but very limited.  

Greg Harter
Columbus Area Railroad Club


doncarter521@...
 

FYI 
Most newer decoders will work with just DC current with no problems. Most manufacturers will state if it will work both ways so check when you purchase. them. 
📞🚂👂


On Feb 20, 2020, at 8:04 PM, Duff & Polly M via Groups.Io <dpmeans@...> wrote:

I am sorry if this has been asked before, or if this question should go elsewhere.
I currently operate DC, mainly because of the number of locomotives that will need work.  I do have a few locomotives that are DCC Ready.
A club I am joining is DCC.  I am thinking I would like to equip one or two of my DCC Ready locomotives with decoders, so they can run at the club.  However, I would also like to use them also at home on my DC layout.

I have heard something about dual mode decoders that can automatically determine whether DC or DCC is available.  If these do what I think they do, are available, and not too too expensive, I am inclined towards this solution.

Are there negatives to this approach, and.or recommended methods?

Thank you.


thomasmclae
 

Most decoders let you set whether the Lok runs on DC as well as DCC.
However, some DCC layouts require you to turn this option off for technical reasons.
Best option is to select some Locs to add DCC, and use those exclusively at the club.
(Note, my club still has DC as well as DCC.)

Thomas
DeSoto, TX 


RONALD ST.LAURENT
 

Greg,

We avoided the DC/DCC thing at our club by purchasing a decoder for each member to install in an engine of their choice.  This was about in the year 2000.  Our club has been around since 1953.

The argument "I have 50 engines for DC" doesn't really hold water when you ask them "How many of them do you regularly run?"

Being a pure DCC club makes things infinitely easier.

Ron

Lansing Model Railroad Club www.lmrc.org


On Fri, Feb 21, 2020 at 9:25 AM Greg Harter <greg1462@...> wrote:
Just for info:  Our club, in Columbus, Indiana, is over 25 years old, and has been running both DC and DCC on the same layout for over 20 years.  We use DCC detector boards, which we designed and built, that preclude a loco going from a DC track to a DCC track, or vice versa.  We have four mainlines, several crossovers and a couple of reversing loops, If the current on two specific mainlines isn't the same (DC or DCC), the crossovers will not operate, and/or the isolated track section between those two mainlines will not receive any current of either type.  We have never had an incident where this did not work, and have not had an incident involved any damage to a loco.  

We planned this originally because we had several members who wanted to run DC and several who wanted to run DCC.  

We did a clinic at the 2016 NMRA in Indianapolis on how this operates.  

Dual mode decoders are okay, but very limited.  

Greg Harter
Columbus Area Railroad Club


thomasmclae
 

Trying to do that for 20 years.
Still some folks that insist on running DC.

Thomas
DeSoto, TX


Jerry Michels
 

Ron wrote: "he argument "I have 50 engines for DC" doesn't really hold water when you ask them "How many of them do you regularly run?""
Also, conversion to DCC doesn't have to be done to all locomotives at the same time.  
Jerry Michels


Jerry Michels
 

Hi Thomas, we've had similar discontent at the Amarillo Railroad Museum, but we just ignore it.  The rule is that we run DCC, no if ands or buts.  We have even disabled running address 00 because it messes with our detection system.  No one is forced to join the museum, so you either comply or take your DC locomotives with horn-hook couplers and plastic-wheeled rolling stock elsewhere.
Jerry


Mark Gurries
 

This topic seems to have derailed into a layout question as opposed to YOUR decoder question.

Almost ALL decoders made past and present support both DC and DCC mode of operation.

The question is not if the decoder will support DC mode but how well it supports DC mode.   You can see a wide variation in the locomotives response to a DC throttle position.  Simply put is will not have as wide of a speed control range than the locomotive had BEFORE you installed the decoder.  Many considered this speed control in DC mode unacceptable.

Some History:  Some time ago, Atlas decided to market a new type of decoder with a marketing name of "Dual Mode”. By Dual ModeTM, they meant the decoder has a physical jumper plug that allows the modeler to select between DC-only operation or DCC and DC operation. With the plug in the DC-only position, a decoder equipped locomotive runs on a standard DC powered (analog) layout with no speed differential when compared to a similar non-decoder-equipped locomotive.  The locomotive shell had a roof top hatch that you removed exposed the jumper so you can change it on the fly.  You then put back the hatch.

These decoders are no long made but it has lead to some confusion in the market place to imply you must buy a specific decoder to run in both DC and DCC mode when that is not true at all.

Finally there is one downside to keeping the DC mode enabled (by default it is typically enabled) when running on DCC.   If there is a momentary short on the track, it can confuse the decoder and it will exit DCC mode and go to DC mode on the fly.   Unfortunately this results in a runaway locomotive under DCC mode where the only way to stop it is to kill layout power or grab the engine.

On Feb 20, 2020, at 5:04 PM, Duff & Polly M via Groups.Io <dpmeans@...> wrote:

I am sorry if this has been asked before, or if this question should go elsewhere.
I currently operate DC, mainly because of the number of locomotives that will need work.  I do have a few locomotives that are DCC Ready.
A club I am joining is DCC.  I am thinking I would like to equip one or two of my DCC Ready locomotives with decoders, so they can run at the club.  However, I would also like to use them also at home on my DC layout.

I have heard something about dual mode decoders that can automatically determine whether DC or DCC is available.  If these do what I think they do, are available, and not too too expensive, I am inclined towards this solution.

Are there negatives to this approach, and.or recommended methods?

Thank you.

Best Regards,

Mark Gurries
Electrical Engineer
DCC Website & NMRA DCC Clinics: www.markgurries.com




Don Vollrath
 

Good rule Jerry. After all it’s your RR and your club.
DonV


Duff & Polly M
 

Thank you for the various replies.

An issue of speed control was mentioned a couple of times; the locomotive with DCC decoder set for DC will not necessarily respond the same way as the locomotive without the decoder, when the locomotive is powered by lower DC throttle settings.  There is a minimum voltage needed before the decoder activates, resulting in a locomotive minimum speed that may be higher than desired.  I had not appreciated this before, although the physics makes sense.

One of the locomotives is a Mantua Pacific, with Vanderbilt tender.  It seems that the decoder is located in the tender, and the tender top is readily removable.  Except for possible problems with repeated removal and insertion of plug and decoder, it should not be inconvenient to swap the two, if the performance with the decoder programmed for DC is not acceptable.

The other locomotive is a Bachmann SD40-2.  I have not yet explored how easy replacements can be done, but my initial thought is that the reduced low speed performance would be more problematic, suggesting swapping, instead of reprogramming, might be necessary.  It was suggested that I dedicate certain locomotives for exclusive use at the club; this solution might be best for the SD40-2.


Duff & Polly M
 

I must take back part of my previous post.  Upon closer examination, the Bachmann SD40-2 is standard DC, although it appears that the motor may be isolated.  Wires from the trucks go to a simple circuit board, which appears to distribute power - both pos and neg -  to the motor and the lamps; no measured conductivity from either to the frame.  That may be a simple, but not necessarily low cost, conversion.  If so, I will make this locomotive dedicated, as I previously mentioned.