The HP 547A Current Tracer is a hand-held probe which enables the precise localization of low-impedance faults in electrical systems. The probe senses the magnetic field generated by a pulsing current internal to the circuit or by current pulses supplied by an external stimulus such as the HP S46A or 10526T logic Pulsers. Indication of the presence of current pulses is provided by lighting the indicator lamp near the Current Tracer tip. Adjustment of probe sensitivity over the 1 mA to 1A range is provided by the SENSITIVITY control near the Indicator. The probe is self-contained and requires <75 mA at 4.5V to 18V, from any convenient source.