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Discussion Boards => General Discussion => Topic started by: DAVISinGP on January 10, 2018, 03:01:58 PM

Title: DC on a DCC Layout
Post by: DAVISinGP on January 10, 2018, 03:01:58 PM
I'm sure every newbie eventually asks a question about this – so I guess it's my turn.  ;)

I've been enjoying my Digital Commander set (DCC) for a few months.

I recently purchased an older style (DC) Bachmann PCC trolley which runs just fine. However when not running, the lights remain on and the motor buzzes. Since I don't run it very often, I don't want to leave it in that state whenever the layout is powered, although I'd like to have it parked somewhere on the layout. Until now, I've been removing it, putting on a separate piece of track close to the layout.

So I've got two questions.

1)   Is this behavior "normal" when running DC equipment on a DCC track?

2)   And if so, is there a way to create a "cutoff" of some sort so that power can be cut to the a stub on which the trolley could sleep?

Thanks.
Title: Re: DC on a DCC Layout
Post by: dutchbuilder on January 10, 2018, 03:13:20 PM
The answer to both your questions is yes.
What you hear is the block modulation of your dcc controller.
Just make a switchable dead siding for your dc locomotive.
Be aware that running a dc locomotive on dcc is not very healthy for the motor.

Ton
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on January 10, 2018, 04:11:47 PM
Thanks, dutch.

A "switchable dead siding" sounds exactly like what I need. What's involved in creating that? Remember that I'm very new at this.  :)
Title: Re: DC on a DCC Layout
Post by: Terry Toenges on January 10, 2018, 06:47:10 PM
                                 /  /   Straight leg
                               /  /
                              /  /
TURNOUT -->         /  /____________________________________
                            /  /______                             _______________Diverging leg
                           /  /         V                              V
                          /  /           l__ ++++++++++__l
                                                 on/off switch

You could do it like this. Cut a gap in one leg and wire an on/off switch with one wire on each side of the gap. Fill the gap with a piece of plastic or glue or something so it doesn't close up. Trim it down so it's even with the rails.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on January 11, 2018, 09:17:07 AM
I appreciate your diagram and info.

Once again, I'm very new at this. So just to make sure I'm on the right track (yes, pun very much intended), since I'm using EZ Track, where would I put the break? Could I just pull out one of the rail connector pins and replace it with the wire to the on/off switch or would you suggest cutting a rail on the track itself?

Thanks.
Title: Re: DC on a DCC Layout
Post by: Bucksco on January 11, 2018, 11:39:26 AM
http://shop.bachmanntrains.com/index.php?main_page=product_info&cPath=258_366_367&products_id=2495
Title: Re: DC on a DCC Layout
Post by: Terry Toenges on January 11, 2018, 11:40:33 AM
Yes. You can remove a rail joiner. They make plastic rail joiners that you could use in place of the metal one. You still have to attach the wire to each side of the gap. You can buy rail joiners with wires attached.  You could use those on the two pieces of track on both sides of the gapped ones. If you want the gap close to the turnout, you can use short pieces of E-Z Track close to the turnout then longer ones past the gap.
Or, you can just cut the gap in the rail and solder the wires on both sides of the gap.
I had forgotten about Bachmann's insulated gap pieces, too. Those would work if you don't want to do it yourself.

           metal joiner        metal joiner                  metal joiner
____________l______________l_________________l_______________
        Joiner with wire       plastic joiner         joiner with wire
____________l_____________  l ________________l_______________
                     V                                                      V
                      l ____________switch_____________l
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on January 11, 2018, 01:43:06 PM
Thanks a lot, you guys. Very helpful info.
Title: Re: DC on a DCC Layout
Post by: Joe323 on January 12, 2018, 09:26:08 AM
You might have difficulty removing the metal joiner from the EZ track.  If so I would just do one of two things. 

Clip off the metal joiner and put a tiny piece of plastic in between the roadbed sections to maintain the gap. Or

Cut the gap in the rail somewhere other than a joint with a dremel tool or maybe track cutters.
Title: Re: DC on a DCC Layout
Post by: jward on January 13, 2018, 07:53:24 AM
I routinely wire my layouts similar to this. Not only does it give you a safe place to park your dc locomotives, it also reduces the load on your command station as well. Dcc locomotives draw power whether you are using them or not, so parking them on isolated tracks will make sure you don't exceed the limits of your dcc system. EZ command is only rated for one amp, and if you have multiple locomotives, especially sound equipped ones, sitting around drawing power you are asking for trouble.

Title: Re: DC on a DCC Layout
Post by: DAVISinGP on January 13, 2018, 10:20:18 AM
Thanks again, you guys.

In educating myself about model railroading, this thread has been a great lesson.  :)
Title: Re: DC on a DCC Layout
Post by: WoundedBear on January 13, 2018, 09:14:33 PM
If it's just a "dead end" siding for parking, I would think just using a power routing turnout would save a lot of wiring and a switch......no?

Sid
Title: Re: DC on a DCC Layout
Post by: James in FL on January 13, 2018, 09:55:21 PM
QuoteIf it's just a "dead end" siding for parking, I would think just using a power routing turnout would save a lot of wiring and a switch......no?

Sid

Great minds think alike.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on January 14, 2018, 10:02:22 AM
Looks like my education continues...

I hadn't heard of a "power routing turnout" but by its name, it sure sounds like it might be a solution. Can it be created/used with EZ Track?
Title: Re: DC on a DCC Layout
Post by: jward on January 14, 2018, 12:40:35 PM
Power routing may not be a good idea with dcc. On a power routing switch, both points and frog are the same polarity as the rail that one of the points is in contact with. That leaves a situation where the wheel backs may brush a point of opposite polarity, causing a momentary short. This is not noticeable on DC, but on DCC it may instantaneously shut down your command station.

I learned this lesson the hard way when I first started using dcc with my handlaid switches, which were easier to build as power routing types. I had to modify my construction methods to eliminate the problem.

Much better with DCC to use an isolated section with an on-off switch (spst) to kill the power.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 07, 2018, 01:42:32 PM
Well, the Power Terminal with Insulated Gap suggested by Yardmaster did the trick and is perfect for my current (pun intended) needs. My old trolley can now rest quietly on a siding.

I have a related question: what would I need to power the "dead" side when and if I want to extend the track a bit?

I have a Digital Commander set with an EZ-Command controller. I presume I will need another source of power for the "other side" that can easily be turned on and off. What would be an easy way to do that?

Thanks.
Title: Re: DC on a DCC Layout
Post by: Flare on February 07, 2018, 02:11:16 PM
I would just wire up a DPDT switch to the 'other side'.

That would enable/disable power to both rails at the same time from your existing controller.

Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 07, 2018, 02:43:43 PM
Quote from: Flare on February 07, 2018, 02:11:16 PM
I would just wire up a DPDT switch to the 'other side'.
Sorry - very new to the hobby. Could you tell me what a DPDT switch is? Thanks.
Title: Re: DC on a DCC Layout
Post by: Flare on February 07, 2018, 03:07:10 PM
Quote from: DAVISinGP on February 07, 2018, 02:43:43 PM
Sorry - very new to the hobby. Could you tell me what a DPDT switch is? Thanks.

Sure.  Basically it's a toggle switch that controls two circuits at once.  Much cheaper than a second DCC controller and you won't have to worry about synchronizing them.

Leave one circuit unconnected and wire the other to the siding's rails and you can turn it off and on with the switch.


You can find a more detailed explanation on the different kinds of switches here:  https://learn.sparkfun.com/tutorials/switch-basics/poles-and-throws-open-and-closed

Title: Re: DC on a DCC Layout
Post by: Terry Toenges on February 07, 2018, 03:34:23 PM
To add to what Flare said, the DPDT abbreviation means "double pole double throw".
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 07, 2018, 04:00:35 PM
Thanks guys.

I hate to act stupid, but in the case of electrical engineering, well, I am.  ;D

If I connect a switch and wires to the "dead" section of track, where is the power coming from? Am I splicing into the existing wire from the controller to the track?
Title: Re: DC on a DCC Layout
Post by: Flare on February 07, 2018, 04:37:54 PM
Quote from: DAVISinGP on February 07, 2018, 04:00:35 PM
If I connect a switch and wires to the "dead" section of track, where is the power coming from? Am I splicing into the existing wire from the controller to the track?

That's one option.  Another would be to tap directly into the gapped track section since it has connectors underneath for both ends.

Just get a pair of Bachmann feeder wires and connect them to both ends of the gapped track with the switch between them.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 07, 2018, 04:40:36 PM
Thanks again.

I was also thinking that perhaps I could pick up power from the other terminal track connector. I have an extra controller-to-track wire assembly - what do you think about utilizing that?
Title: Re: DC on a DCC Layout
Post by: Flare on February 07, 2018, 04:48:20 PM
The other side of a terminal rerailer?  That will work too.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 07, 2018, 05:09:23 PM
Thanks for all your help.

My education continues...
Title: Re: DC on a DCC Layout
Post by: Warflight on February 08, 2018, 08:57:01 PM
All of this is great advice... I too have a few DC engines I run on my layout, and yes, I pull the engines off the track when not in use.

Lately, I've been making an effort, to put a decoder in each engine I can (obviously, it's not happening with the Gandy Dancers, or the DeWitt Clinton, or the John Bull, but the Norris engines have space in the tender, and the motors are already isolated, and it's just two wires to solder)

If your engine has an 8 pin plug (or if you're feeling squirrely enough to hard wire) I would suggest a simple (cheap) decoder for it... if you can.

Otherwise, if all you're doing is using it every so often, and taking it off the track, or putting it on an isolated track, you're still fine with it.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 09, 2018, 10:13:28 AM
If I leave one line connected to the other side of the "split", can I use an SPST on the other lead, or is there some reason I should use the DPDT to both?
Title: Re: DC on a DCC Layout
Post by: Flare on February 09, 2018, 11:35:46 AM
Quote from: DAVISinGP on February 09, 2018, 10:13:28 AM
If I leave one line connected to the other side of the "split", can I use an SPST on the other lead, or is there some reason I should use the DPDT to both?

A SPST would work too, I suppose which switch you use is a matter of personal preference.

In my case I prefer not to have any power going to a segment that's supposed to be turned off.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 09, 2018, 12:33:08 PM
Quote from: Flare on February 09, 2018, 11:35:46 AM...I prefer not to have any power going to a segment that's supposed to be turned off.
That makes sense.
Title: Re: DC on a DCC Layout
Post by: jward on February 10, 2018, 08:23:40 PM
what you are doing with an on off switch  to control power to a section of track is a time tested concept that was used for many years before DCC came along. It is known as block control. Using only one rail to control the section via a single pole switch is also time tested, known as common rail wiring, where one rail acts as a common return to the power supply, similar to a grounded chassis in electronic equipment. Unless you have a special situation such as a reversing loop, there is no need to isolate both rails, or use a double pole switch. In your case, where you are merely killing power to a section of track, a SPST, or on-off switch will do just fine. Just be sure that the contacts can handle the current output of your power supply. In the case of EZ command, with a 1 amp output, a switch you can buy in Radio Shack with contacts rated 3 amps will be more than enough.

The concept here can also be applied as many times as you want on your layout. You could, for example, have every siding on your layout isolated, and park all your locomotives in their own track when not in use.
Title: Re: DC on a DCC Layout
Post by: DAVISinGP on February 12, 2018, 12:01:58 PM
Thanks for that info, Jeffery.