Abstract: Low-cost, miniature, noninvasive power and continuity testing tools for diagnosing and troubleshooting electrical and electronic systems. The tools may be used to diagnose the condition of electrical equipment such as power cords, ignition wires, and ignition systems. Certain tools do not require a power source to operate, while others are battery powered. One tool comprises a liquid crystal display and an antenna connected a LCD element of the display. RF energy radiated by a tested circuit is sensed by the antenna and is coupled to the LCD element which causes the element to emit light. Another tool comprises a battery, a light emitting diode, and a semiconductor integrated circuit switch. The light emitting diode and integrated circuit switch are coupled in series with the battery. The integrated circuit switch is closed when it is in the presence of RF energy, which completes the circuit and turns on the light emitting diode.

Abstract: Nonintrusive tools for testing power and continuity of AC circuits and wiring. Each tool has a conductive probe extending therefrom that is coupled to a positive terminal of power source or is electromagnetically coupled to a coupling wire that is coupled to the power source. A switching/amplifying device is coupled in series with an indicator between terminals of the power source. A contact is coupled to a switching terminal of the switching/amplifying device that is used to operate the tool when touched by a user. An external coupling device having two electrically isolated wires that are twisted around each other to provide electromagnetic coupling therebetween may be employed when the coupling wire is not used. Physical touching of the contact by the user activates the tool. Once the user activates the tool, the probe may used to directly contact “hot” AC terminals or contact a gel placed on unexposed wires to enhance operation of the tool to determine the presence of power or continuity.