Abstract: The disclosure describes an improved apparatus for measuring the flow of current through a conductor by means of a Hall generator. The Hall generator is biased by a constant current source employing feedback. In order to increase the accuracy of the current measurement, operational amplifiers having inputs which float in relationship to the power supply operating the amplifiers are used to amplify the Hall generator output voltage and to drive a meter. The current measuring apparatus can be used to detect defects in a vehicular alternator by measuring the fluctuating components of the alternator output current. The magnetic field generated by the current to be measured is concentrated in the area of the Hall generator by means of a unique hollow, cylindrical, coiled strip of metal made from nickel, molybdenum and iron. The apparatus includes a regulator in which the voltage drop is so low that a 3.25 volt regulated supply can be maintained from a poorly-charged 6-volt battery.

Abstract: A series regulating transistor supplying voltage to a supply bus from a vehicular battery in which circuitry samples voltage from the supply bus for generating a correction signal for controlling operation of the regulating transistor. A first switching transistor of a starting circuit biases the regulating transistor into a conductive state in response to the connection of the battery to the apparatus and a second switching transistor switches the first switching transistor OFF responsive to the voltage level developed on the supply bus.

Abstract: The disclosure describes an improved automated engine diagnosing device employing a digital data processor computer and a cathode ray tube display monitor which displays engine parameter (i.e., condition) values in alphabetic, numeric, and graphical form. Some data is accumulated from the engine by means of direct digital measurements, whereas other data is obtained from the engine by an analog-to-digital converter. The data is then processed by the computer and displayed on the cathode ray tube display monitor.

Abstract: An improvement in an analog oscilloscope for an automotive ignition analyzer is disclosed. The improvement is a short store circuit which enables substantially complete display of the secondary coil voltage, including the peak amplitude of the firing line voltage.

Abstract: Various improvements in an analog oscilloscope for an automotive ignition analyzer are disclosed, including, among others, a short store circuit which enables the full amplitude of the firing line voltage to be displayed and a sweep trigger circuit which correlates engine speed and sweep length.