Abstract: The transmitter of the circuit breaker locator draws large amplitude, short duration, phase locked unipolar pulses of current from the power source at a frequency lower than that of the AC line frequency. The audible and visual indicators of the transmitter are triggered at the rate of the current pulses drawn from the AC line. The receiver of the circuit breaker locator has a pick-up coil that responds to magnetic field surrounding the circuit breaker, an amplifier for boosting the signal from the pick-up coil, and a single shot pulse stretcher triggered by the amplifier. The pulse stretcher drives both audible and visual signals, and at the same time charges a memory capacitor in a staircase generator fashion. The magnitude of the memory capacitor voltage in turn controls the gain of the amplifier. A switch controls the voltage applied to the amplifier, which increases by a predetermined amount when released.

Abstract: A self-contained, plug-in, hand-held device for testing the current carrying ability of the Hot wire and the Safety Ground return of standard AC outlets which have Hot, Neutral and Ground connections. The test circuit device also detects common miswires and open connections in the AC outlet being tested by way of flashing lights built into the tester unit. If the AC outlet is wired correctly and the total resistance of the Hot and Safety Ground are below a predetermined limit, only one light "Green" meaning "OK" will flash, which use of only one light to indicate everything is properly wired makes the device easy to use even by a user with little knowledge of electrical testing devices and procedures. Various other detection conditions and indications of occurrence are afforded by the test circuit device.

Abstract: An automatic ranging clamp-on ammeter includes an openable normally closed magnetic core for encircling an A.C. current carrying cable has a measuring winding and a sensing winding. A current meter, a diode rectifier and a pair of variable first and second resistors are connected in series across the measuring winding. A relay solenoid is shunted by a Zener diode and is connected in series with a variable resistor across the sensing winding. A sensitivity reducing shunt variable resistor is connected through the relay normally open contacts betwen the junction of the first and second resistors and the meter opposite terminal. An audible signal generator may be connected across the shunt resistor. When the measured current exceeds a predetermined value the relay closes and inserts the shunt resistor across the meter to reduce the measuring sensitivity and increase its range and energizes the audible signal generator.