This will work fine ...
... until you accidentally connect centre rail and catenary while both have power (this will most likely kill your digital controller or the booster)

I presume that for a moment, nothing will happen. Then, after a second or so, nothing will continue to happen.
Read more at http://www.brainyquote.c...html#PBlYo8iXFm3Ufmpm.99

But I haven't tried that - and I won't put my controllers at any risk to find out ...

Better turn both off both analogue and digital power before fiddling with rolling stock (especially tin plate stuff) or tools on the layout.

I have done 2 layouts now with the following solution, for those who have a few analogue items they want to run from time to time, but are mainly digital operators:

1: On a normal digital layout, I take one loop/line of track and wire it independently from the rest of the layout. The only permanent contact is K83 decoders working the switch motors, and 2-3 switches that join the loop to the main layout- on which with C track I isolate BOTH the hot and ground contacts as a security measure.

2: This leaves a possible ground joint from outer rail to outer rail at the switch, but that is it. (and I'm pretty sure it doesn't really matter anyways)

3: I then have 3 way toggle switches for both hot and ground wires to the isolated line. I use 3 way as I like taking both switches to the "off" position in the center as a security measure before flipping from one current to another. Via these switches I can route power to the rest of the layout, or to an analogue transformer.

It works like a charm, but like Ian recommends it basically just enables a very independent analogue loop on the layout. No trains cross over or anything like that. it does leave the benefit of the K83 keeping digital switch control while you run analogue trains though- which is nice.

Love the highly technical technical analysis of potential failure!! "Fails Unless Constantly Kicked" !!

I actually did this for some time on a former layout some years back - the brown/'ground'/common remained connected all the time, but I was also very particular to keep the Red (Stud&Catenary) wiring very distinctly separate. It enabled me to run some older non-converted Loco's along with the Digital ones, in fact against the common advice I used the overhead for Digital and the stud for Diesels & Steam. I had no problems with the Digital off the overhead but at that time I had all older style decoders as well - 6080 & 6090 which seemed quite happy with it, but I understand the potential problems with some of the newer decoders that are more sensitive to the possible erratic contact made by the pantograph.

Keep those Reds away from each other, and above all else, don't cross the beams, keep out of the nebula, and always keep the flux capacitor loaded to capacity, you never really know when you are going to need 1.21 Gigawatts in a hurry!!

Cheers

Cookee

Great to read the experiences above. So I have an MS1 (60652) which is powered by a Marklin 16V AC transformer via the digital adaptor "ugly box" (60115). That works fine for digital locos on an Mtrack layout. I would like to run analogue locos from the catenary and the two systems would share the track as a common ground. (I also noted above not to accidentally connect the centre rail with the catenary when putting on metal carriages etc).
The question is, can I use the same 16V AC transformer to supply the catenary (analogue locos) and to supply the digital system via the digital adaptor?
Does the digital adaptor (60115) have some kind of floating transformer with a switch mode power supply or does it only use a bridge rectifier? If it is the latter, I think that my proposal to use the same transformer for both systems may not work, because a part of the rectifier in the adaptor would be short-circuited because of the shared ground?
Similarly, can I use that same transformer to supply my Mtrack points and signals because these also use the track as a common ground for the lights.
Or would I encounter the same problem?

I>M>H>Opinion, experimenting with too many different power connections, and trying to divide, or separate a layout, signals, and or tirnouts, can result in severe shorts and spikes which can damage digital controllers. Especially newer ones like a CS2, CS3, MS2, etc. which use switched mode power supplies. Mixing these with older conventional tranmsformers is asking for trouble.
If a short circuit doesn't trip the controller saftey quick enough, damage can occur to them, and locomotve decoders.

Don't do this, this will destroy the MS1.
There cannot be a common ground between the input side and the output side of any Mobile Station or any digital controller that uses an H bridge on the output side.
This setup was possible with the 6020/6021 and 6604/66045.

Seems to me that you are better off connecting the turnouts to the yellow-brown of an AC transformer with 7072 box. This powers the switch light and controls solenoid separate from digital track power, and lowers power draw. (You can use red-brown of that AC transformer for scenery incandescents)

Added: this does require shared track ground between AC and digital, which others seem to discourage.

Edited by user 18 October 2023 13:45:35(UTC)  | Reason: Not specified

Hi Sven,

as long as there is no, but really not any contact between the two circuits, you can do what you asked.
And as long as the signal has not been deteriorated, you will not have any contact.
Why?
Because on analogic layout, you did not have any contact between track and catenary, so why should you have in semi-digital?

Good old 7239 old type (with the same relais as 7039) and 7188 had a fixed pair of red cables to connect on the track, and a pair of connectors for the catenary.
Newer models (flat relais) had two pairs of climp connectors, which you could use on your choice for track or catenary. In fact, it's the same relais as 7245 but 7245 has no signal lights.
See p.25 (pdf-page 26) in this document: https://www.marklinfan.n...cumenti/SignalManual.pdf

you connect your track to H and K (one inside the controlled sector, one on the central), and your catenary to L and N (one inside the controlled sector, one on the transfo).



If you read a little bit spanish - I did not find the english version... https://www.marklin-spai...y_conduccion_Marklin.pdf