MÄRKLIN H0 conventional driving and electromechanical automatisation

 

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Märklin-H0-Knowledge

Circuits for advanced users – Automation of Processes

Components and their circuit diagrams

 

state: 12.02.2026 12:26

 

 

This page explains the circuit diagrams used in my circuits.

If you are a real electrical expert and have any suggestions for improvement, please let me know.

 

General circuit symbols

Circuit symbols are the elements that make up circuit diagrams and schematics.

 

Connections and intersections

 

Symbol for two wires that cross but have no electrical contact with each other:

   

Symbols for lines that are electrically connected to each other:

General circuit symbol for a connector on a component, a terminal, a solder lug, a socket:

The dotted line represents the transition from the inside of the component to the outside.

Special circuit symbol for a socket or terminal:

Special circuit symbol for a plug:

Circuit symbol for "ground", connection "0" on the Märklin transformer,

potential of the Märklin rails, the track body of the M track

Circuit symbols for light sources

 

Contacts

A contact connects two wires and has only two possible positions: closed or open.

Contacts are always shown in the device's rest position.

Many commercially available switches and relays have not only simple normally closed and normally open contacts, but also changeover contacts that switch back and forth between two contacts.

 

Circuit symbol for a contact that is open in the rest position, a normally open contact:

Circuit symbol for a contact that is closed in the rest position, a normally closed contact:

Circuit symbol for a changeover switch, the combination of a normally open contact and a normally closed contact:

 

Types of operation

In order for a contact to move and switch, we need something to activate it.

 

Symbol for manual operation, one button:

The dashed line represents the mechanical connection to the contact.

Symbol for manual operation with a rocker lever, here with three locking positions:

Circuit symbol for actuation by a coil:

And we need something to reset it.

 

Symbol for automatic reset, e.g., by a spring:

Circuit symbol for actuation and reset by a double coil that pulls an iron core back and forth:

 

Terms for electrical components

Relay:
A switch that is electrically actuated by at least one solenoid coil. Usually with 1, 2, or 4 changeover contacts.

Monostable:
Switches, regardless of the type of actuation, that return to a rest position after actuation are "monostable".
Pushbuttons, toggle switches with pushbutton function, simple relays.

Bistable:
Switches that remain in their current position after being actuated are "bistable".
Märklin signal drives and universal remote switches are bistable.
Push buttons with ballpoint pen mechanisms, toggle switches, and slide switches, which are also available with three positions, are tristable.

There are commercially available bistable relays that are significantly cheaper and smaller than universal remote switches. I prefer to use these.

 

General components

Now we combine the circuit symbols to form circuit diagrams, or functioning components.

Let's look at the circuit diagram for a manual switch, i.e., a switch contact that is open in its rest position and is closed manually. When the hand is removed, it returns to its rest position (standard switch).

 

General circuit diagram of a pushbutton with spring return, open in rest position:

We look at the circuit diagrams of commercially available relays with two changeover switches.

 

General circuit diagram for a monostable relay with 2 changeover switches, automatic reset:

General circuit diagram for a bistable relay with 2 changeover switches:

 

 

Märklin H0 components with switching function

The Märklin H0 contact track:

 

My special design for Märklin H0 contact track, in which the conductive wheel set performs the switching function. One rail is connected to "0", while the other is connected to the socket.

 

The Märklin H0 switch track:

 

My special circuit diagram for a Märklin H0 switch track, two normally open contacts, mechanically operated.

A switching tab transfers the movement of a slider to one or the other normally open contact, depending on the direction of travel. Springs restore the unactuated state.

The normally open contacts connect "0" to one of the two sockets. The socket at the rear in the direction of travel is switched.

 

The Märklin universal remote switches.

 

Special circuit diagram for the Märklin universal remote switch No. 7045:

7045 has 6 connections:
4 wires and 2 sockets.

7045 has only one switch.

Connection and function:
Yellow wire to "L" on the transformer,
blue wires with red and green plugs optionally activated briefly(!) to ground "0" coils,
red wire is connected to one of the sockets.

7045 is bistable, so it remains in its current position even without control voltage. It has a manual switch lever.

Special circuit diagram for the Märklin universal remote switch No. 7245:

7245 has 10 connections:
3 wires and 7 terminals.

7245 has 1 changeover switch and 2 normally open/normally closed contacts.

Connection and function:
Yellow wire to "L" of the transformer,
blue wires with red and green plugs optionally activated briefly(!) to ground "0" coils.
Terminal 2 switches between terminals 1 and 3,
normally open/normally closed between terminals 4 and 5 and between terminals 6 and 7.

7245 is bistable, meaning it remains in its current position even without control voltage. It has a manual switch lever.

Special circuit diagram for the Märklin universal remote switch No. 7244:

7244 has 15 connections:
3 wires and 12 terminals.

7244 has 4 changeover switches.

Connection and function:
Yellow wire to "L" on the transformer,
blue wires with red and green plugs optionally to ground "0" activates the changeover.
Terminal 2 switches between terminals 1 and 3,
of which there are 4 sets.

The control voltage may also be applied continuously to 7244.

7244 is bistable, i.e., it remains in its current position even without control voltage.
It is fully electronic and therefore has no manual switch lever.

 

The conventional Märklin H0 signals.

Märklin H0 signal drives are bistable and therefore remain in their current position even without control voltage.

Manual operation is possible at the wings of the semaphore signals, while the light signals with magnetic drives have an control lever.

First, the minimalist circuit diagrams:

Only the double-coil drive and the contacts it moves are relevant for the layout control.

 

Simplified circuit diagram for signals
    446/11 or   7039, block semaphore signal
    446/12 or   7040, exit semaphore signal
    446/21 or   7042, protection signal
    446/41 or   7044, block light signal
    and               7188, block light signal.

Connection and function:
Yellow wire to "L" of the transformer,
blue wires with red and green plugs optionally activated briefly (!) to ground "0" activates coils, the two red wires are connected for "proceed" signal and disconnected for "stop" signal.
The second contact between the sockets works in exactly the same way.

Simplified circuit diagram for signals
    446/13 or   7041, shape entry signal, and
    446/22 or   7043, shape exit signal

Connection and function:
Yellow wire to "L" of the transformer,
blue wires with red, green, and orange plugs optionally activated briefly(!) to ground "0" coils, the two red wires are connected for the "Go" signal and disconnected for the "Stop" signal.
The second contact between the sockets works in exactly the same way.

This is the complete circuit diagram for the 446/22 or 7043 fly shunting signal.

Simplified circuit diagram for signals in the 72xx series.

As I do not own any signals in this series, I can only speculate on the design of the drives based on the structurally similar 7245 universal remote switch.

The circuit diagram shown should apply to 7239 and 7240. An eighth terminal is used to connect the lamps to ground.

Connection and function:
Yellow wire to "L" of the transformer,
blue wires with red and green plugs optionally activated briefly(!) to ground "0" coils.
The terminals on the normally open contacts are connected when the signal is "Go" and disconnected when the signal is "Stop"”

The changover switch is used to control the signal lights. Under certain circumstances, these connections can also be used for control purposes.

Signal 7241 has a third coil that activates an additional normally open contact. This signal therefore has a larger drive and 3 more terminals than shown in the circuit diagram.

And now with all the details and full range of functions:

 

Special circuit diagram
for the shape block signal 446/11 or 7039 and
for the shape protection signal 446/21 or 7042:

Basic function plus 1x continuous light with ground connection as a socket and via the base plate.

Special circuit diagram
for mold ejection signal 446/12 or 7040:

Basic function plus 2x continuous light with ground connection as socket and via the base plate.

Special circuit diagram
for the 446/13 or 7041 shape entry signal:

Basic function plus 2x continuous light with ground connection as a socket and via the base plate.

Third coil for actuating the second wing. Common reset via the "stop" coil.

Special circuit diagram for the shape pre-signals
    446/1 or 7036 and
    446/2 or 7037:

Drive for mechanics only. Static light.

Special circuit diagram
for the 446/3 or 7038 shape advance signal:

Two double coils as drives for the disc and the additional wing. Static light.

Special circuit diagram
for light block signal 446/41 or 7044:

Basic function plus 2x light, switched alternately via changeover switch, with ground connection as socket and via the base plate.

Hand lever for manual operation.

Special circuit diagram
for light block signal 7188:

Basic function plus 2x light, switched alternately via changeover switch, with ground connection as socket and via the base plate.

Connection sockets for advance signal.

Hand lever for manual operation.

Special circuit diagram
for the 7239 light block signal:

Circuit diagram still unknown, as I do not yet own such a signal.

Siehe derweil Produktbeilage zu 7239

Special circuit diagram
for the 7240 light block signal:

Circuit diagram still unknown, as I do not yet own such a signal.

Siehe derweil Produktbeilage zu 7240

Special circuit diagram
for the 7241 light block signal:

Circuit diagram still unknown, as I do not yet own such a signal.

Siehe derweil Produktbeilage zu 7241

Special circuit diagram
for light advance signals 7187 and 7236:

7187:
Connection to the red and green sockets of 7188.

7236:
Color-true connection to the terminals of 7239.

Signal terms:
Vr0 = 2x yellow, Vr1 = 2x green

Special circuit diagram for light advance signal 7237:

Connect to the terminals of 7240 according to the instructions.

Presumed circuit diagram. No guarantee!

Signal terms:
Vr0 = 2x yellow, Vr2 = 1x yellow and 1x green;
the second green lamp always remains dark.

Special circuit diagram for light advance signal 7238:

Circuit diagram still unknown, as I do not yet own such a signal.

Siehe derweil Produktbeilage zu 7238

The follwing circuit diagrams show the full range of functions of the other conventional Märklin H0 mahnetic products:

 

Special circuit diagram for turnouts with lanterns:
5117 to 19,
5137 to 39,
5202 to 04,
5140 to 42, and the
double slip turnout 5128.

Note: Some old M track turnouts with large lanterns have a socket in the track body as a ground connection for signals, for example.

Special circuit diagram for the 5214 three-way switch:

Special circuit diagram for the double slip turnout 3600 DKWS / 5126 / 5013

Special circuit diagram
for double slip turnout 5207 until 1981:

The rail in the middle of the crossover was switched from the center conductor in the straight switch position to ground in the diverging position.

Special circuit diagram for the double slip turnout 5207 from 1982 onwards:

Special circuit diagram
for decoupling track 5112:

Level crossings 7057, 7192, 7292, 7592, 74920, 74923, 74924:

Connection:
Yellow wire to "L" terminal of the transformer,
plug connection in the middle under the track to special railroad crossing contact track,
or via wire to command device "Close".

 

 

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