Abstract: An exercise system including an exercise device having a user actuatable pedal mechanism coupled to a permanent magnet, DC motor operated as a generator and a load control arrangement for controlling a braking effect exerted by the DC motor on the pedal mechanism. The output of the DC motor is connected to a power dissipation circuit including plurality of power MOSFETs. The system can be operated in a constant power or a constant force mode. In the constant power mode, the load control monitors the output of the DC generator and compares it with a selected power level and in response to detected errors between the signals, adjusts the conductivity of the power MOSFETs to maintain the power output independent of actuation speed. Current flow through the power MOSFETs is monitored and the relative conductivity between the MOSFETs is adjusted in order to maintain substantially equal current flows through each MOSFET.

Abstract: An ECG system is disclosed having amplification circuitry which, while effectively blocking electrical transients resulting from undesirable low frequency electrical artifacts, nevertheless maximizes the continuity of receipt of desirable heart activity indicating information. The ECG system employs a DC coupled amplifier including an integrating circuit for effectively reducing the DC gain of the amplifier to substantially zero and for providing a pass band gain of about 1,000 at frequencies above about 0.05 Hz. A fast acting saturation sensing circuit is also incorporated. The saturation sensing circuit resets the integrating circuit to offset any artifact produced signal and to thereby minimize loss of the desired ECG hear activity indicating information.

Abstract: A constant speed hydrostatic drive system is disclosed wherein a generator drive shaft is maintained at a constant speed by utilizing an electro-hydraulic controlled displacement pump responsive to a pressure transducer to control a hydraulic motor. A speed sensor is used to produce a direct current signal responsive to the drive shaft speed. The signal is converted into a series of voltage pulses also responsive to the shaft speed which are compared to a speed reference signal to provide a speed error signal. A loop gain control means is provided to utilize said speed error signal to adjust the shaft speed to coincide with said reference signal. A timing reference and digital trim control are also provided to compensate for long term drifting in the type speed control circuit described above.

Abstract: A linear solid state servo amplifier operated from a low voltage source and which develops a voltage across the servo motor equal to the source voltage diminished only by the saturation voltages of two of its output transistors has a bridge output stage of complementary transistors and a bridge driver stage of complementary Darlington transistors having as its load a preselected resistor.

Abstract: A machine tool such as a multiple spindle automatic machine tool is provided with a motor acting through a slippable clutch on each of the multiple spindles to rotate the spindles and each spindle is provided with a brake to brake each spingle to a stop. A spindle rotational means is provided to rotate the spindle at a speed less than that established by full engagement of the clutch. This is accomplished by partial engagement of each the clutch and brake so that each slips. A spindle positioning means is further provided to position the spindle at a desired arcuate position. At such time the clutch is disengaged and the spindle is locked in rotational position. The clutch and brake are differentially controlled to control the relative average torque transmission therethrough to maintain a desired slow speed.

Abstract: A solenoid operable from an alternating voltage source is disclosed and the solenoid may actuate a fluid valve with the fluid of the valve wetting the movable armature inside a barrel. The barrel is sealed against fluid leakage at all places except the axial end connected to the valve. A frame is coaxial with the barrel and encloses an electrical coil. A magnetically permeable core is inside the barrel and fixed relative to the frame and this core carries a first pole piece. A second pole piece is on the movable armature for cooperation with the first pole piece. The electrical coil is energized with rectified voltage from the alternating voltage source and this together with the shape of the pole pieces establishes a controlledsaturation of these pole pieces in a range of positions of the armature. This saturation of the pole pieces is established so that the saturation decreases as the armature moves from a first extended position toward a second closed position.