Abstract: A motor controller for use on a treadmill to prohibit the treadmill from operating at a high speed immediately upon energization. The controller uses solid state circuitry in a motor speed circuit with a speed setting potentiometer set by the user. The system is adapted so as upon energization a minimum speed is initially achieved. The results are obtained with the interaction of a buffer circuit, solid state circuitry, and an SCR motor speed control circuit.

Abstract: An apparatus for controlling a motor comprises an oscillator for providing a source of periodic signals, and a divider for converting the oscillator output into desired motor rotation frequency signals. A tachometer generates actual motor rotation frequency signals and a comparator compares the actual and desired motor rotation frequency signals and generates a rotation frequency error signal. The tachometer and the divider are coupled to the comparator. An SCR bridge controls motor rotation frequency. The comparator is coupled to the SCR bridge. An AND gate coupled to the source of periodic signals provides a counting gate during which periodic signals from any suitable source are to be counted and a counter coupled to the AND gate counts the periodic signals. A display displays the number of such periodic signals counted during the counting gate.

Abstract: Apparatus for mounting TO-220 solid state device packages on a heat sink. Each package includes an electrically conductive, heat dissipating, heat sinking tab which is common with one of the electrical terminals, and a resin case. The heat sinking tab includes an opening therethrough intended to be used in mounting the package to a heat sink. The apparatus comprises a printed circuit board mounted to the heat sink. An opening is provided in the board. The devices are adapted to be oriented during mounting so that they overlie the opening with their heat sinking tab sides facing toward the opening and their resin case sides facing away from the opening. A first bar of thermally conductive material is adapted to be positioned between the heat sink and the heat sinking tab sides of the packages and extending through the opening. A layer of electrically insulative and thermally conductive material is interposed between the bar and the heat sinking tab sides of the packages.

Abstract: A method for heat sinking a TO-220 solid state device package includes the steps of mounting the device from a printed circuit board, mounting the board from a heat sink and providing an opening in the board. The device is oriented during mounting so that it overlies the opening with its heat sinking tab side facing toward the opening and its epoxy case side facing away from the opening. A bar of thermally conductive material is positioned between the heat sink and the heat sinking tab side of the package and extends through the opening. A layer of electrically insulative and thermally conductive material is interposed between the bar and the heat sinking tab side of the package. Aligned passageways are provided through a second bar of thermally conductive material, the layer of electrically insulative and thermally conductive material, the first bar and the heat sink.

Abstract: A system for stabilizing the output of a voltage-to-frequency (V/F) converter having an input terminal and an output terminal. The system comprises a single-shot having an input terminal and an output terminal. The output terminal of the V/F converter is coupled to the input terminal of the single-shot. An integrator comprising an operational amplifier is coupled in integrating amplifier configuration for coupling the output terminal of the single-shot to the input terminal of the V/F converter. The operational amplifier comprises a difference amplifier. The integrator includes a capacitor coupled between one of the input terminals of the difference amplifier and the output terminal of the difference amplifier. The output terminal of the difference amplifier is coupled to the input terminal of the V/F converter.

Abstract: A speed-control system for an electric motor comprises a circuit for setting a desired motor speed and providing a speed-control signal, a circuit for sensing motor voltage and providing a motor voltage-related signal, a circuit for sensing current flow in the motor and providing a motor current-related signal, a summing point for combining the sensed current and sensed voltage-related signals to provide a motor speed-related signal, and a triggerable switch for combining the motor speed-related signal and the speed-control signal to provide an error signal for controlling the motor speed.

Abstract: An overload-sensing circuit for an electric motor driven by an alternating signal comprises a supply line connecting the motor to a power source, a resistance in the supply line, and a first comparator for measuring the phase relationship between the power source voltage signal and the motor current signal. A variable resistor is employed to select a phase relationship which represents a load limit for the motor. A second comparator compares the measured phase relationship to the selected phase relationship and produces a signal representing an overload condition of the motor when the measured phase relationship generally equals the selected phase relationship.

Abstract: A tachometer comprises a magnet having north and south magnetic poles and a magnetically operated switch for sensing movement of the magnet and for producing an output signal in response thereto. The magnet is supported on one end of a shaft which is supported for rotation in a bearing. The other end of the shaft is threaded into the rotating member, the output of which is to be measured. The bearing is mounted on a plate so that the plate and shaft are independently movable. The switch is mounted on the plate in proximity to the magnet to detect movement of the magnet. The frequency of the output signals produced by the switch indicates the rate of rotation of the rotating member.