Abstract: A switching circuit has an operational amplifier connected between positive and negative supply lines and has its non-inverting input terminal connected through a resistor to an intermediate supply line. The inverting input terminal of the amplifier is fed with a signal the polarity of which varies with respect to the intermediate input terminal, and a capacitor and a resistor are connected in series between the output and non-inverting input terminal of the amplifier. The arrangement can be used in a control circuit for an electrically driven vehicle.

Abstract: A control circuit for an electrically driven vehicle has contactors for determining the direction of operation of the motor, but these contactors cannot be operated until the current flowing through the motor is below a predetermined level.

Abstract: A d.c. control circuit includes a slew-rate limiting circuit interposed between a current sensing device which detects current in a load and a control circuit, for switching on and off a thyristor controlling current through the load. The circuit limits the slew rate to a level in excess of the maximum normal current slew rate through the load.

Abstract: A control circuit for an electrically driven vehicle has a switch with a central off position, and operative positions in which the motor of the vehicle drives the vehicle forwardly and rearwardly. Delay means is provided operable when the switch is in its central off position for maintaining energisation of the control circuit for a predetermined period of time, so that loads are not deenergised as the switch is moved through its off position to change the direction of operation of the truck. In the preferred form, movement of the switch to its off position reduces the demanded armature current to zero.

Abstract: In a control circuit for an electrically driven vehicle, a traction motor drives the vehicle and there are contactors so that the motor can provide forward drive or electrical braking. The current in the motor armature is controlled by a pedal which also controls the contactor means. The action of the pedal can be modified in accordance with the position of the brake pedal of the vehicle.

Abstract: In a control circuit for an electrically driven vehicle, there is an accelerator pedal which when depressed sets the armature current of a traction motor, and a brake pedal which when depressed provides electrical braking of the vehicle. The electrical braking is inhibited unless the vehicle speed is above a predetermined value.

Abstract: A control circuit for an electrically driven vehicles has a traction motor the armature of which can be connected between positive and negative supplies lines in either sense to drive the vehicle in either direction. Also, the armature is connected through a diode to one of the supply lines to permit electrical braking.

Abstract: In a control circuit for an electrically driven vehicle, there is a thyristor chopper circuit which sets the current flow in a traction motor to a demanded level. The motor is capable of driving the vehicle forwardly or in reverse, and is also capable of effecting electrical braking. Whenever the motor is switched from its forward drive to its forward braking condition, or vice versa, the demand signal is set at a low level for a predetermined period.