This paper will be presented to the connection diagram of the two motors to one power supply line, which allows for independent control of each of them.
The scheme was designed to supply model railway and enables to control two "trains" in one way - to regulate the speed and direction of their movement, independently of each other.
However, this scheme can be successfully applied in any other cases that require such an independent regulation. With more powerful load need only replace the circuit elements on the other, designed for high currents and voltages.
Electric motors (DC) in each of the train any models can be calculated on the supply voltage of 3 to 12 volts.
It requires small refinement: sequentially to each of the two engines will need to include a diode, one forward, the other in the opposite direction, as shown in Fig.
The scheme is extremely simple, does not contain any active elements (transistors, chips) and does not require any adjustments after assembling at serviceable parts and properly selected supply voltages.
Transformers can be secondary windings with an alternating voltage at 12... 24 volts, depending on the nominal value of supply voltage electric motors.
Note that the load (motors) will be "reach" voltage equal to approximately half the supply voltage of the secondary winding and, based on this, to select the desired transformer.
Power transformers are also dependent on the load power. For a small-sized power supply model railway will be enough transformers with a capacity of 10... 20 watts.
All diodes in this circuit can be any rectifier, with a permissible reverse voltage of not lower than 50 volts and a current greater than 0.5 amperes (e.g. D226, KD105 or foreign 1N4001... 1N4007).
Variable resistors - resistance of 10 to 100 ohms and a power of 10 watts (wire).