Abstract The armature of the model electric locomotive motor is connected as one arm of a bridge circuit having a D.C. supply voltage. When the armature is held to prevent rotation, the bridge is balanced by means of resistors in the other arms so that no voltage appears across the output. When the armature then rotates the voltage across the bridge output is the back EMF produced by the rotation of the armature. A variable reference voltage obtained from the same D.C. power source is introduced opposing the back EMF and the resultant is used to control the current between the power supply and the bridge. The armature back EMF is thereby held by the bridge balance essentially equal to the reference voltage and if a heavy load is applied to the armature shaft the resultant bridge unbalance will retain the desired armature rotational speed constant irrespective of load changes, but variable directly with the applied reference voltage. Acceleration control is achieved by introducing a capacitor-resistor circuit in the output of the reference voltage circuit to simulate the acceleration performance in railroad trains. Braking control is achieved by an additional transistor-capacitance-resistor circuit added to cause a controlled deceleration rate when the reference voltage is set back to zero thus simulating the actual braking effect in train air brake systems.
A current supply for model railroads having a driving motor connected for receiving current therefrom which comprises a continuous DC speed control circuit controlling the armature current as a function of the counter electromotive force developed by rotation of the driving motor armature thereby to regulate the armature rotational speed, comparison means in which said counter electromotive force is compared to a speed control reference voltage of predetermined magnitude derived by a voltage divider across a DC supply, means controlling the current supplied to the motor armature with the resultant differential voltage, storage capacitor means for retaining a charge proportional to the reference voltage and switching means selectively controlling the charge and discharge of said capacitor means to simulate braking and acceleration.
Claim 2
Dependent Claim
122 words
A current supply for model railroads having a driving motor connected for receiving current therefrom which comprises a continuous DC speed control circuit controlling the armature current as a function of the counter electromotive force developed by rotation of the driving motor armature thereby to regulate the armature rotational speed, comparison means in which said counter electromotive force is compared to a speed control reference voltage of predetermined magnitude derived by a voltage divider across a DC supply, means controlling the current supplied to the motor armature with the resultant differential voltage, storage capacitor means for retaining a charge proportional to the reference voltage and switching means selectively controlling the charge and discharge of said capacitor means to simulate braking and acceleration.
Claim 3
Dependent Claim
108 words
A current supply for model railroads having a driving motor connected for receiving current therefrom which comprises a continuous DC speed control circuit controlling the armature current as a function of the counter electromotive force developed by the rotation of the driving motor armature thereby to regulate the armature rotational speed having a control for increasing or reducing said current to said amature, a capacitor connected to retain and control current from a source for supply to said armature after said control is operated to reduce current, said capacitor connected for charging when said current is increasing to thereby effect acceleration control for the speed of said armature.
Claim 4
Dependent Claim
108 words
A current supply for model railroads having a driving motor connected for receiving current therefrom which comprises a continuous DC speed control circuit controlling the armature current as a function of the counter electromotive force developed by the rotation of the driving motor armature thereby to regulate the armature rotational speed having a control for increasing or reducing said current to said amature, a capacitor connected to retain and control current from a source for supply to said armature after said control is operated to reduce current, said capacitor connected for charging when said current is increasing to thereby effect acceleration control for the speed of said armature.