Bidirectional DC motor control circuit including overcurrent protection PTC device and relay

An electric circuit comprising a direct current electric power source, a bidirectional direct current electric motor and a bidirectional motor rotation control arrangement coupled between the electric power source and the electric motor, the power source having a positive output and a negative output, the motor having a positive input, a negative input, a full forward rotational position and a full reverse rotational position, the control arrangement comprising:

• a. a control element, coupled in series with the motor, the control element comprising
• (1) an interrupt component having a closed state in which it can carry a normal circuit current and an open state in which it can carry at most a reduced circuit current, including no current, and
• (2) a sense component comprising means for sensing, when the motor rotates from one of the full positive position or the full negative position to the other of the full positive position or the full negative position, when the motor reaches said other position, and
• (3) a control component comprising means for changing the interrupt component from the closed state to the open state when the sense component senses that the motor has reached said other position;
• wherein
• (4) the interrupt component and sense component are coupled as a series combination, and the series combination is coupled in parallel with the control component;
• and
• b. a switch element, comprising
• (1) means for coupling
• (i) the positive output of the power source with the positive input of the motor, and
• (ii) the negative output of the power source with the negative input of the motor, and, alternatively
• (2) means for coupling
• (i) the positive output of the power source with the negative input of the motor, and
• (ii) the negative output of the power source with the positive input of the motor;
• wherein,
• A. with the motor in the full forward rotational position, the interrupt component in the closed state, and the switch element coupling the positive output of the power source with the negative input of the motor and the negative output of the power source with the positive input of the motor, the motor rotating to the full reverse rotational position, wherein the control component, upon the sense element sensing that the motor has reached the full reverse rotational position, causing the interrupt component to change from the closed state to the open state, thereby removing power from the motor, and
• B. with the motor in the full reverse rotational position, the interrupt component in the closed state, and the switch element coupling the positive output of the power source with the positive input of the motor and the negative output of the power source with the negative input of the motor, the motor rotating to the full forward rotational position, wherein the control component, upon the sense element sensing that the motor has reached the full forward rotational position, causing the interrupt component to change from the closed state to the open state, thereby removing power from the motor.