A ribbon loudspeaker is provided by a first set of three rows of parallel spaced apart magnets disposed on a first plate, a second set of three rows of parallel spaced apart magnets disposed on a second plate, a diaphragm having a U-shaped electric current conductor disposed on one face thereof and means for clamping the diaphragm in a spaced apart and aligned relationship with both said sets of rows of magnets. The conductor is comprised of thin layers of metal of different compositions, prefer...

A hearing aid employs a permanent built-in rechargeable storage cell or battery, and a solar cell or other photo cell which powers the electronics of the hearing aid and recharges the storage cell. Favorably, a thin film amorphous silicon cell is employed, and is affixed onto an outward-facing surface of the aid. The photocell is connected in parallel with the storage cell and is of sufficient power capacity to power the amplifier and recharge the storage cell under average ambient light conditi...

A control for a polyphase a.c. motor having field coils, each of which is connected to first rectifiers connected to form a first junction and second rectifiers connected to form a second junction and a transistor controlling the current between the first and second junction in response to a control signal.

A reversible control circuit for applying voltage pulses of opposite polarities to a load whereby the average current flowing in the load is a function of the maximum voltage at which the voltage pulses are applied and the duty cycle of the control circuit. The circuit may be utilized to control an electric motor field wherein the motor shunt field winding is connected across a four switch bridge circuit supplied from a direct current or rectified alternating current power source. Current flow i...

A system for establishing the speed of an electric motor, particularly a direct current motor. The principal use is in the control of a drive motor for a photocomposition machine font disc. The speed is controlled by spacing pulses of power to the motor. The pulses are derived from a central output of a left shift--right shift register. Shift in one direction is obtained from a uniform clock source, and in the opposed direction from a generator responsive to motor speed. When the motor speed cau...

A digital circuit for translating each input command pulse into an incremental step of a digital motor in which the input pulses may be received at any rate while the pulses to the motor and hence the motor velocity are produced at rates which is within the motor's ability to change its velocity. The system uses a digitally operated circuit that can be easily adjusted to different motor velocity abilities and also enables control over both directions of motor movement.

A current limiting impedance network for a dryer control in which a controlled conduction device, such as an SCR, is connected to shunt an AC motor to selectively prevent operation of the motor, in which a current limiting, power dissipating resistor is replaced by a lower value and lower power rating resistor and a capacitor connected in series with the resistor. The capacitor has a capacitive reactance of a value approximately twice the inductive reactance of the motor to provide substantially...

Apparatus for synchronizing the relative positions of motor-driven machines. Preliminary to operating the machines in synchronism, the rotors of individual synchronous motors that drive the machines are moved to a stop at certain angular positions. The angular positions are such that when inverter voltage is thereafter applied to the stators of all of the motors from a common inverter, the instantaneous angular position of the stator magnetic field with respect to the respective rotor is the sam...

A starting control system for synchronous motors is provided in which the usual separately mounted discharge resistor is eliminated. A relatively high resistance coil of small size is wound on each field pole, in addition to the normal field winding, and these coils are connected together and utilized as a discharge resistor during starting of the motor.

A brushless a.c. synchronous motor comprises a stator assembly having a stator winding which is supplied with power by an invertor. The main input power to the invertor flows through the primary winding of a transformer the secondary winding of which supplies current by way of a rectifier, to a field winding of the rotor assembly of the motor.