Abstract: An apparatus and method for determining a current state of charge of a battery are disclosed. The apparatus includes a battery signal developer, a threshold developer, a comparator, and a bi-directional integrating device. The battery signal developer receives a battery voltage and develops a corresponding battery signal. The threshold developer receives an integration result signal based on an integration value representative of the current state of charge of the battery, and develops a threshold signal based on the integration value. The comparator provides first and second comparison signals, respectively, when the battery signal magnitude is greater than and less than the threshold signal magnitude. The integrating device accumulates the integration value and receives a comparison result signal based on the first and second comparison signals.

Abstract: An apparatus is provided for testing semiconductor devices. The apparatus tests the impedance of the semiconductor devices in both conducting and non-conducting states to detect semiconductors whose impedance in the conducting state is too high or whose impedance in the non-conducting state is too low. The apparatus uses a battery source for low voltage d.c. The circuitry for detecting when the impedance is too high in the conducting state includes a lamp in series with the battery source and the semiconductor device, whereby the impedance of the semiconductor device determines whether sufficient current will flow through the lamp to cause the lamp to illuminate. A d.c. to d.c. converter is provided to boost the voltage from the battery source to a relatively high voltage d.c. The relatively high voltage d.c. can be connected by a switch to circuitry for detecting when the impedance of the semiconductor device in the non-conducting state is too low.

Abstract: A field replaceable silicon controlled rectifier (SCR) heat sink with reliable thermal and electrical connection to the SCR or other electronic device for an electronic circuit forming part of a vehicle control. The SCR heat sink includes two discrete heat sink blocks having opposed parallel faces between which an SCR or other electronic device may be properly clamped. At least one insulator hold down bar and an associated spring overlie a flange on the lowr end of each block and facilitate clamping the blocks to a base plate. The blocks are clamped to the SCR by a force distributing spring and bolts for properly applying a clamping force to the SCR or other electronic device.

Abstract: Apparatus is disclosed for controlling the speed of an electric motor by selectively connecting a field weakening resistor across the field winding of an electric motor. A first means is provided for comparing the field voltage to a fixed reference voltage and for generating a first signal in response to the field voltage falling below a first predetermined value and a second signal in response to the field voltage rising above a second predetermined value. A second means responsive to the first and second signals is provided for selectively connecting a field weakening resistor across the field winding of the motor in response to the field voltage falling below the first predetermined value. The second means responsive also disconnects the field weakening resistor in response to the field voltage rising above the second predetermined value.

Abstract: The voltage of a battery connected to a load is monitored to provide a continuous instantaneous indication of the voltage level of the battery and to provide an indication that the battery voltage has fallen to some critical level. Means are provided for generating a control signal which is representative of the battery voltage when the apparatus is operated in the battery testing mode and an independent voltage when the apparatus is operated in the self-testing mode. A first indicator means responsive to the control signal is provided for continually indicating the instantaneous level of the battery voltage when the apparatus is operating in the battery testing mode and the instantaneous level of the independent voltage when the apparatus is operating in the self-testing mode.

Abstract: The voltage of a battery connected to a load is automatically indicated with respect to two voltage levels. A first indicating means indicates that the battery voltage is greater than a first voltage level, and a second indicating means indicates that the battery voltage is less than the first voltage level but greater than a second voltage level. A third indicating means indicates that the battery voltage is less than both the first and second voltage levels and disables the load connected to the battery.Means are provided for selectively generating a control signal either in response to the battery voltage or at a decay rate independent of the battery voltage. In a normal operating mode, the control signal is determined by the actual decay rate of the battery voltage whereas, in a self-test mode, the control signal decays at a fixed decay rate independent of the actual battery voltage. The first, second and third indicating means operate in response to the control signal.