Abstract: A current measuring device for measuring a current flowing in a conductor by inductive coupling to the conductor, the device having an E-shaped core of magnetic material and a slidable bar normally spaced by an air gap from one outer leg and being slidably movable away from this outer leg to permit the insertion of the conductor being measured. Two pairs of windings are placed on the other outer leg. One winding in each pair is alternately energized under the control of a transistor oscillator network, the other winding in each pair being used to supply feedback voltages to cause deenergization of the transistor then conducting. Each transistor has in series therewith a second transistor to minimize clipping of the voltage peaks. The output of the windings is applied to the input of a further transistor, the output of which is in turn applied to a current measuring device.

Abstract: A sawtooth wave form generating circuit in which the amplitude of the sawtooth wave form is automatically maintained at a constant value by passing the same through a variable gain amplifier, measuring the amplitude of the sawtooth wave form at the moment when it reaches its maximum value, comparing such amplitude with that of a standard voltage and adjusting the gain of the amplifier accordingly. This is done through the use of a capacitor which is charged upon the occurrence of the same pulse which discharges the capacitor of the sawtooth wave generator. The capacitor controlling the gain of the amplifier is charged under the control of a comparator amplifier having one input from the output of the variable gain amplifier and the other from a source of standard voltage. The sawtooth wave generator is particularly applicable for use in measuring phase differences between two events recurring at a variable repetition rate such as encountered in automobile ignition diagnosis.