Abstract: A speed control circuit for a DC motor includes a digital-to-analog (D/A) converter, a regulator/controller, and a control circuit which applies a compensating current to the DC motor that compensates for variations in loading applied to the motor. The regulator/controller compares a reference voltage provided by the D/A converter with a feedback signal provided by the motor to generate a signal to activate the control circuit, thus to supply a compensating current to the motor.

Abstract: A solid-state, four terminal optical relay has a current regulator with two input pins, and an output switch with two output pins. The relay includes an optical isolator assembly so that the current which causes switching of the relay is optically, rather than electrically, transmitted to an output switch driver. The relay includes an internal current overload detect and latch circuit which operates if the relay is switched on into a shorted load, or if a short is switched in across the load while the relay is on. The current overload detect and latch circuit is sufficiently fast to permit the relay to be continuously pulsed into a shorted load without damage to the relay.

Abstract: An apparatus for treating a patient which induces an electric current in the body through external application of an electromagnetic field. The apparatus includes means for controlling the magnitude of the induced electric current by sensing the electromagnetic field and automatically controlling its strength. The sensing may be accomplished through time multiplexed use of the field inducing coil or through the use of a separated, dedicated coil.

Abstract: A blood pump system in which a roller pump is provided for pumping blood through a flexible tube. A low voltage D.C. motor is provided having an output shaft. An electrical control circuit is connected to the motor for applying the necessary voltage to drive the motor at a predetermined speed. Gearing means are provided connecting the motor's output shaft to drive the roller pump. Means are optically coupled to the motor for controlling the speed of the motor. Means are connected to the optically coupled means to determine the blood flow rate being pumped though the tube by the pump. Means are provided which display a digital readout of the flow rate. The roller pump is provided with an arcuate bearing surface, which carries the flexible tube, the bearing surface defining an arc of approximately 168.degree.. Lead ramps extend from each end of the bearing surface and are substantially tangent to the end of the surface from which the respective ramp extends.

Abstract: A blood pump system in which a roller pump is provided for pumping blood through a flexible tube. A low voltage D.C. motor is provided having an output shaft. An electrical control circuit is connected to the motor for applying the necessary voltage to drive the motor at a predetermined speed. Gearing means are provided connecting the motor's output shaft to drive the roller pump. Means are optically coupled to the motor for controlling the speed of the motor. Means are connected to the optically coupled means to determine the blood flow rate being pumped through the tube by the pump. Means are provided which display a digital readout of the flow rate. The roller pump is provided with an arcuate bearing surface, which carries the flexible tube, the bearing surface defining an arc of approximately 168.degree.. Lead ramps extend from each end of the bearing surface and are substantially tangent to the end of the surface from which the respective ramp extends.

Abstract: An improved control circuit which may be incorporated into a medical transcutaneous nerve or muscle stimulator for disabling the output from the stimulator to stimulation electrodes connected thereto upon the occurrence of an undesirable output event of the kind which may result in an electrical shock or burn to user of the stimulator. This disablement by the control circuit may be triggered when electrode impedance exceeds a threshold level, or when the current level of the output undergoes excessive change, or when the power source to the unit is interrupted. Included may be visual signaling functions.

Abstract: A transmitter/receiver module which includes circuitry for receiving serial digital data in diphase non-return-to-zero (NRZ) format and for demodulating said data into a separate synchronizing signal, data signal and clock signal and which further includes circuitry for transmitting the received and modulated signal or other modulated signals input directly to the module, such /transmitting circuitry including means for modulating the clock signal, data signal and synchronizing signal into the prescribed diphase NRZ format for output through a transformer coupled transmission line. The module further includes an oscillator for realigning the clock signal received with the serial digital data.

Abstract: A clock phasing circuit for aligning data which is transmitted by a first clock, running at a particular frequency, with a second clock running at the same frequency as the first clock but in a different and undetermined phase relationship. The incoming data includes a synchronizing signal which initiates the operation of the clock phasing circuitry so that the data is alternately clocked into each of a pair of flip flops by successive pulses from the first clock. Each flip flop is individually connected to one of the inputs of one logic gate of a pair of gates which are alternately enabled by successive pulses from the second clock. The outputs from the two logic gates are combined by a further logic gate so that the data is reformed in alignment with the second clock.