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Offline aclassifier  
#1 Posted : 03 January 2014 21:14:23(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 64
Location: Trondheim
I have decided to do this mix on a small layout.

I assume the Märklin transformer will survive an accidental short between the two circuits, but will the digital connection box? If not, is there a fix for it, like suitable zener?

I have written a small blog note about my rationale: http://www.teigfam.net/oyvind/home/models/079-connecting-catenary-wires/

Øyvind Teig
Trondheim Norway
Offline kbvrod  
#2 Posted : 03 January 2014 21:17:16(UTC)
kbvrod

United States   
Joined: 23/08/2006(UTC)
Posts: 2,597
Location: Beverly, MA
nope.
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Offline RayF  
#3 Posted : 03 January 2014 22:40:46(UTC)
RayF

Gibraltar   
Joined: 14/03/2005(UTC)
Posts: 15,435
Location: Gibraltar, Europe
Hi Øyvind,

I would not risk a short between the two "live" systems. The raw AC would most likely destroy the output transistors on the digital controller if they were accidentally shorted together.

Can you not wire them so that only one of the two systems can be energised at the same time? This would give you the ability to run both the digital and analogue trains, but not simultaneously. I have an arrangement on my layout where I can switch either my analogue controller or my MS2 to the centre studs. The ground rails are connected as common return to both. This works well and I can change between analogue and digital at the flick of a switch.
Ray
Mostly Marklin.Selection of different eras and European railways
Small C track layout, control by MS2, 100+ trains but run 4-5 at a time.
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Offline Webmaster  
#4 Posted : 03 January 2014 22:51:42(UTC)
Webmaster


Joined: 25/07/2001(UTC)
Posts: 10,844
What tracks are you using? For K-tracks there are "ski lifters" to the slider pickup ski does not make contact with with both current circuits.

The problem is that you should never short the pickup slider between the 2 current feed systems. Not good at all...
You can of course make your own "ski lifters" too with a round plastic popsicle stick or so.
The important thing is make sure the slider has no contact with both circuits at any time via the centre rail "pukos".

And, common ground in the outer rails is essential...


If you plan to use catenary only for AC, it is doable - but you should then remove the slider from the loco so it can travel from catenary only.
And as mentioned earlier - common ground for both systems.

But - If the loco derails you might get into problems if the wheels are shorted towards the digital centre rail while under AC power from the catenary...
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
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Offline aclassifier  
#5 Posted : 03 January 2014 22:51:51(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 64
Location: Trondheim
Ray

Good idea! However, my layout is quite small that I have no track real estate to park the nonpowered locos. I would have to swap all locos to and from the layout, quite difficult with catenary above I think.

What about a small series resistor from the digital controller box when I run mixed? I could switch it in with a relay, and also switch in protection diodes or zeners. I would at max run 3 locos at the same time, and I could accept two. If the output transistors are weak, how about changing them? And how about the booster box?

Are the circuit diagrams available anywhere?

Øyvind
Offline aclassifier  
#6 Posted : 03 January 2014 22:55:18(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 64
Location: Trondheim
Originally Posted by: Webmaster Go to Quoted Post
What tracks are you using? For K-tracks there are "ski lifters" to the slider pickup ski does not make contact with with both current circuits.

The problem is that you should never short the pickup slider between the 2 current feed systems. Not good at all...
You can of course make your own "ski lifters" too with a round plastic popsicle stick or so.
The important thing is make sure the slider has no contact with both circuits at any time via the centre rail "pukos".

And, common ground in the outer rails is essential...


M-track. What's a ski lifter?
Ø

Offline Webmaster  
#7 Posted : 03 January 2014 22:57:44(UTC)
Webmaster


Joined: 25/07/2001(UTC)
Posts: 10,844
Please see my previous post, updated now...
Juhan - "Webmaster", at your service...
He who asks a question is a fool for five minutes. He who does not ask a question remains a fool forever. [Old Chinese Proverb]
Offline Hoffmann  
#8 Posted : 03 January 2014 23:04:20(UTC)
Hoffmann

Canada   
Joined: 25/11/2004(UTC)
Posts: 1,106
Location: Guelph, Ontario

Hi,

My opinion is to be absolutely sure of no short between the two systems to install a short piece of M-Track ( #5129 ) and insulate the centre rail on either side.

That way no short with the slider is possible.

Martin
marklin-eh
Offline clapcott  
#9 Posted : 03 January 2014 23:08:10(UTC)
clapcott

New Zealand   
Joined: 12/12/2005(UTC)
Posts: 2,244
Location: Wellington, New_Zealand
Originally Posted by: kbvrod Go to Quoted Post
nope.


Concur, do not even try !!
Peter
Offline H0  
#10 Posted : 03 January 2014 23:12:18(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 13,505
Location: DE-NW
Hi!
Originally Posted by: aclassifier Go to Quoted Post
I assume the Märklin transformer will survive an accidental short between the two circuits, but will the digital connection box? If not, is there a fix for it, like suitable zener?
There is not technical protection (Dr Dirt wrote that already).
You don't need a ski lifter (aka centre rail rocker) if you use AC only for catenary.

An accidental short will only do harm if the catenary is under power. So always set the catenary to 0 when you put trains on the track or take them of to minimise the risk.

You can limit the damage by using a cheap booster for the centre rail. If you do not need mfx feedback, the cheapest boosters will be Märklin Delta Controls 6604 or 66045.

For mfx locos you can use a programming track without catenary connected directly to your controller - and then you need a centre rail rocker between controller section and booster section.
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline river6109  
#11 Posted : 04 January 2014 01:08:07(UTC)
river6109

Australia   
Joined: 22/01/2009(UTC)
Posts: 12,569
Location: On 1965 Märklin Boulevard just around from Roco Square
Øyvind,

I wouldn't attempt to try your experimental concoction, if you have metal overhead masts, a metal loco and a live centre rail you only need a derailment or an accident whereas the loco comes off, touches the metal mast and bingo your experimental concoction is out the window and your money is down the drain

John
https://www.youtube.com/river6109
https://www.youtube.com/6109river
5 years in Destruction mode
50 years in Repairing mode
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Offline mike c  
#12 Posted : 04 January 2014 05:14:42(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 6,368
Location: Montreal, QC
The possibility of the metal lok body conducting the AC from the catenary to the tracks in an accident had not occurred to me. However, it is my belief that a short involving contact between the analog AC and the outer rails would not cause damage to the digital controller. The same could not be said for contact between the live catenary and the third rail, as this would result in both main and return power being supplied to the output terminals of the digital controller. This makes it essential that all locomotives and cars have the power selectors correctly positioned and that no jumpers or leads inside the loks or cars/coaches connect the two voltage sources.

I had a number of old Marklin lamps, which were wired so that the lamp mast served to conduct one of the two leads. In an accident, a lamp fell over and contacted a metal coach. The lamp had been incorrectly connected and this resulted in a short which damaged the coach. I have been very careful since then to mark the leads and do not use any metal accessories around my digital tracks.

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Offline mike c  
#13 Posted : 04 January 2014 05:18:56(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 6,368
Location: Montreal, QC
Originally Posted by: Webmaster Go to Quoted Post
If you plan to use catenary only for AC, it is doable - but you should then remove the slider from the loco so it can travel from catenary only.
And as mentioned earlier - common ground for both systems.

But - If the loco derails you might get into problems if the wheels are shorted towards the digital centre rail while under AC power from the catenary...


I would think that the threat would be more if the catenary wire would either contact the third rail or a metal lok body that was in contact with the third rail during an accident or unsafe operation (i.e. when putting a lok on the rails). You would have to have a section of track for railing your trains without catenary and then slide them under the wires before running them.

The best solution would be to have parallel tracks where you could have an analog and a digital circuit. My plan was to have a digital mainline using R4 and R5 which would basically be an oval with a show section and a station. In the station, this mainline would meet a local line using R3. The local line would meander around a little more and would perhaps be more alpine in design. This line could be analog AC (Maerklin) or two rail DC (Trix) using C Track.
The other possibility would be to have a classic Maerklin analog set up on the interior of the layout using R1 and R2.
My plan was that I might opt for a H0m narrow gauge setup (Bemo) for the layout interior, which would leave only the R3 line for AC analog or DC operation, which could be done relatively easily if I used K track and made my own connections to the track. That track would have to be separate from the mainline to avoid an AC/DC short.

Regards

Mike C
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Offline H0  
#14 Posted : 04 January 2014 09:38:06(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 13,505
Location: DE-NW
The question of mixing analogue via catenary and digital via centre rail has been discussed many times before - and even Märklin Magazine wrote it can be done.

The new aspect of this thread is the question if there is a technical protection for the digital controller (I'm afraid there is none).

Older threads:
https://www.marklin-user...Supplies.aspx#post433696
https://www.marklin-user...peration.aspx#post280906
https://www.marklin-user...e-layout.aspx#post348360
https://www.marklin-user...-Madness.aspx#post361446
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline aclassifier  
#15 Posted : 04 January 2014 15:21:36(UTC)
aclassifier

Norway   
Joined: 18/03/2012(UTC)
Posts: 64
Location: Trondheim
Originally Posted by: H0 Go to Quoted Post

The new aspect of this thread is the question if there is a technical protection for the digital controller (I'm afraid there is none).


I have HW background, and I would be surprised if it's impossible to find some limited running mode where it's possible to protect the digital control box. I haven't studied the modulation, but I assume it's not 100% modulated, only overlayed. But I would need some more data, like the circuit diagram of the control box. Is it available somewhere? Here's a brainstorm list:
  1. Introducing some current limitation (like a resistor) might help the output transistors in the control box if the digital gets connected to AC.
  2. Then, voltage limiting diodes could limit the voltage and thereby give more control of the max current.
  3. I would also limit the current out of the AC transformer, to one-two locos. And two-three digital locos.
  4. Also, design some detection circuitry that could trap the digital output might perhaps also be a way to proceed. It's most often heated overload that kills a transistor, so I assume one would have several ms to detect this.
  5. Or running the AC through a diode bridge to perhaps limit any negative overcurrent if necessary. I think old analogue motors also run on DC?

Øyvind
Offline Renato  
#16 Posted : 04 January 2014 16:14:27(UTC)
Renato

Italy   
Joined: 19/03/2004(UTC)
Posts: 976
Location: Gorizia, Italy
Originally Posted by: aclassifier Go to Quoted Post
Originally Posted by: H0 Go to Quoted Post

The new aspect of this thread is the question if there is a technical protection for the digital controller (I'm afraid there is none).


I have HW background, and I would be surprised if it's impossible to find some limited running mode where it's possible to protect the digital control box. I haven't studied the modulation, but I assume it's not 100% modulated, only overlayed. But I would need some more data, like the circuit diagram of the control box. Is it available somewhere? Here's a brainstorm list:
  1. Introducing some current limitation (like a resistor) might help the output transistors in the control box if the digital gets connected to AC.
  2. Then, voltage limiting diodes could limit the voltage and thereby give more control of the max current.
  3. I would also limit the current out of the AC transformer, to one-two locos. And two-three digital locos.
  4. Also, design some detection circuitry that could trap the digital output might perhaps also be a way to proceed. It's most often heated overload that kills a transistor, so I assume one would have several ms to detect this.
  5. Or running the AC through a diode bridge to perhaps limit any negative overcurrent if necessary. I think old analogue motors also run on DC?

Øyvind


Hi Øyvind,

Of course they can run on DC but the current absorbtion is greater than on AC, therefore the motors overheat and could be damaged.
Another issue is the overvoltage needed to change direction of travel.

Cheers

Renato
Offline kbvrod  
#17 Posted : 06 January 2014 03:29:55(UTC)
kbvrod

United States   
Joined: 23/08/2006(UTC)
Posts: 2,597
Location: Beverly, MA
Originally Posted by: kbvrod Go to Quoted Post
nope.


Hi all,
As Tom and Juhan have stated,...the ski/shoe "lifters" were originally designed to separate digital/analogue areas and also digital areas,...for larger layouts.I remember a a M layout in France that had (3) 6021's on one massive layout (2 on the track and one on the catenary),...early days of MM digital. Cool

And yes,IF you can switch between the two power supplies,you can do it,......


Dirt

Offline mike c  
#18 Posted : 06 January 2014 04:59:01(UTC)
mike c

Canada   
Joined: 28/11/2007(UTC)
Posts: 6,368
Location: Montreal, QC
Here's an interesting twist to this saga… If you place an analog lok on a digital layout, it takes off in one direction at full speed. Here is my question. If you take the output of a 6021 controller and run it through the speed control of a regular transformer (already limited to 0-19VAC), would you technically be able to control the voltage (i.e. speed) and possibly also generate a reverse pulse. If so, you could potentially use the same power supply and controller for both analog and digital sections and the outputs of the 6021 would then not see any power surge from the analog section of the layout.

Any thoughts?

Regards

Mike C
Offline BrandonVA  
#19 Posted : 06 January 2014 17:03:55(UTC)
BrandonVA

United States   
Joined: 09/12/2011(UTC)
Posts: 2,533
Location: VA
Originally Posted by: kbvrod Go to Quoted Post
Originally Posted by: kbvrod Go to Quoted Post
nope.


Hi all,
As Tom and Juhan have stated,...the ski/shoe "lifters" were originally designed to separate digital/analogue areas and also digital areas,...for larger layouts.I remember a a M layout in France that had (3) 6021's on one massive layout (2 on the track and one on the catenary),...early days of MM digital. Cool

And yes,IF you can switch between the two power supplies,you can do it,......


Dirt



I have heard of the ski "lifters" before, but never seen one. Was there a Marklin product number for these? Or just a homemade option?

-Brandon

Offline H0  
#20 Posted : 06 January 2014 17:57:50(UTC)
H0


Joined: 16/02/2004(UTC)
Posts: 13,505
Location: DE-NW
The numbers for the centre rail rockers are 385550 for M track, 385580 for K track, and 204595 for C track (nowadays maybe needing a leading E).
Regards
Tom
---
"In all of the gauges, we particularly emphasize a high level of quality, the best possible fidelity to the prototype, and absolute precision. You will see that in all of our products." (from Märklin New Items Brochure 2015, page 1) ROFLBTCUTS
UserPostedImage
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Offline kbvrod  
#21 Posted : 06 January 2014 18:17:19(UTC)
kbvrod

United States   
Joined: 23/08/2006(UTC)
Posts: 2,597
Location: Beverly, MA
Originally Posted by: BrandonVA Go to Quoted Post
Originally Posted by: kbvrod Go to Quoted Post
Originally Posted by: kbvrod Go to Quoted Post
nope.


Hi all,
As Tom and Juhan have stated,...the ski/shoe "lifters" were originally designed to separate digital/analogue areas and also digital areas,...for larger layouts.I remember a a M layout in France that had (3) 6021's on one massive layout (2 on the track and one on the catenary),...early days of MM digital. Cool

And yes,IF you can switch between the two power supplies,you can do it,......


Dirt



I have heard of the ski "lifters" before, but never seen one. Was there a Marklin product number for these? Or just a homemade option?

-Brandon



Hi Brandon,all,
They actually came (2 of each,see Tom's post) with the 6021.

Dirt
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