Abstract: An apparatus for locating electrical conductors and short circuits in AC and DC circuits is disclosed herein. The apparatus has leads for connecting across open circuit breaker or fuse box terminals. Current limiting resistors and transistors limit the current, if AC or converted to pulsated DC, to a value that is sufficiently high to be read on a clamp-on ammeter at any point in the circuit being tested. A first pulse generator intermittently interrupts the current through the current limiting means to create a momentary pulse of approximately 1/2 to 1 second duration at a frequency of approximately 3 to 5 seconds. A second pulse generator interrupts the current limiting means at approximately 225 cycles per second to provide a pulsating component in the momentary pulse for DC circuits. A clamp-on ammeter will indicate this pulse at all points in the circuit except at the short circuit, whether in a DC or AC circuit.

Abstract: Apparatus for locating a conductor or a short circuit in the wiring of a AC or DC circuit is disclosed. The apparatus is portable and useful in the troubleshooting of complex control systems or the like with the aid of a clamp-on ammeter. Typically, the apparatus is connected in the fuse circuit to be tested, and a pulsating current of low pulse rate is supplied by a solid-state relaxation oscillator which opens and closes a relay bridging the fuse terminals or other convenient circuit point. Where the fuse circuit to be tested is a DC circuit and both AC and DC circuits are in a common conductor bundle, a separate astable multivibrator acts to supply a higher frequency pulsating current superimposed on the low pulse rate pulsating current. The location of a particular conductor or a short circuit is then easily found with the aid of a clamp-on ammeter.