Hi everyone, I am designing my layout, and the more I read, the more confused I am. Being Polish and being a retired(I am a Medic, not a Mechanic). . So far, I want 3 large circuits and block signals. What equipment do I need? CS3+ and power pack for that. What do I use for signals, and what do I use for turnouts? Do I need separate circuits for the block signals? Thanks, guys for the help.

First of all to educate you on feedback mechanisms. Marklin has three types and you need some form of getting the information to your controller. The most commonly used is the contact track. It requires the most work on your part but once installed is very reliable. Marklin three tracks power allow the outside tracks to be isolated and then recognize when there is something on them that connects them. So any car with ac wheels can be recognized. Their advantage is they will show continuous occupancy as long as there is an ac wheel set on them. This is great for block control. The problem is they do not recognize dc wheel sets.
The second most popular is circuit tracks. They require minimal effort on your part and can recognize which direction the train is going. However they need a slider to activate them. Easiest way to think of them is like a three position light switch with the middle position being off and the other two positions indicating what direction the train is going. The problem they have is they only report when the slider is on the switch so not very usable for block control. Plus any car that has a slider for lighting also activates it.
Marklin also sells reed switches. They are kind of a pain as you need to install a magnet under a car or loco and a sensor on the track. The advantage is very selective activation. But they are fussy. Also no direction sensing.
More than likely you will want to use the contact tracks for block control. It is possible to do block control with the the others but long consists can cause problems for them.

Hi guys, and thank you for the information. I am using K Track. So it seems that circuit tracks for block signals works best. Next question, I worked for Norfolk Southern for some years and when the locomotive passes the signal, it turns from whatever aspect was there to red/stop. Can I do this with block signals, i.e., from green to red?

Hi Jon

Various circuits A large layout means you need to divide your layout into zones powered by a booster (I use a CS3 for may medium layout with 26 locos powered similtaneously)

Multiplying the number of boosters above one's real need leads to excessive wiring, additional costs and make Märklin richer.

It also calls for digital feeders (I use 2,5 mm² in a star wiring starting from the CS3 or the booster)

Power supply Since over 10 years I use a 100W power pack (60101) to get 5 A of digital power for each unit (against Märklin advice to reserve these for larger scales.) and I never observed a negative effect. Staying at 3 A limit means you need to increase A LOT the number of boosters because of unbalanced load

Block signals Because I use Rocrail to drive my trains, signals are cosmetic only (only in visible places and only when you finances allows them). The advantage is reduced wiring (no more stop zones or brake zones, no flickering of lighted cars when crossing a stop section).

Which types? Depending on your selected era III or VI you may prefer semaphores or light signals. Signalling may be complex and interesting but is a very important cost item.
My preference is for semaphores (Flügelsignale) because I like era III and because you may see their position from any direction.

Separate circuit? It is best to have a separate circuit for all switches and signal commands. This allows you to run analog trains on occasions

Catenary? It is nice to have to operate electrics but accessibility is terrible espacially when combined with covered platforms (avoid this combination at all costs).
Having catenary only on a portion of the layout is excellent (still plausible to use steamers and have a steam depot.

Radius and tracks The best Märklin track is the C track excellent contacts and durability, lacks flexible track but easdy to come by with large radii. Must paint the rail flanges in dark rust color. R1 is fine for the very very large majority of Märklin locos but not so realistic so better use from R2 or R3.
Avoid using slider operated contact tracks which sooner or later will cause slider take off at small speeds.

Quality wiring It is important because tracking a short circuit in a large layout may become very difficult:
- observe color codes
- use labels for various circuits Booster n,
- a ground wires are permanently connected (soldered) while the "B" connections must allow easy deconnection for tracking shorts
- distribute decoders (m83, m84, m88 close to where they are needed. The feedback cables should not be tightly tied to avoid mutual parasitic induction.
- prefer a CS3 with a Link88 to a CS3+ leaving you with only ONE bus for feedback
- install the WiFi router at least one meter away from the layout.
- install a test track connected to the main CS for registering locos and testing them
- do not use 100% of your decoders as extensions and changes are inevitable.
- keep track of addresses of various decoders (address, etc) labels and records on excel sheets are very helpful.

My layout is certainly not a good example but you learn by doing the bad things
https://www.youtube.com/watch?v=PGSgeDmzgWM

Cheers
Jean