Abstract: A novel apparatus for determining the location of an inoperative bulb in a series circuit of decorative Christmas tree type light bulbs is provided which comprises a housing member having an opening adapted to accommodate the physical insertion therein of each of the light bulbs to be tested while in said series circuit. An elongated electromagnetic radiation shield is fixedly secured within said opening and along the inner peripheral surface thereof and an elongated electro-magnetic radiation receptor is fixedly secured along the inner peripheral surface of said shield and insulated therefrom and adapted to intercept electromagnetic radiation which is radiated from a light bulb inserted therein. A battery operated audio amplifier is mounted within said housing and has an input terminal and an output terminal. An energizable signal indicator is fixedly secured to said housing.

Abstract: A magnetic and variable-volume sound producing device which comprises a housing member, a substantially planar acoustic-producing diaphragm supported along its peripheral edge by the housing, a spiral, multi-turn and electrically conductive coil fixedly secured to the diaphragm and adapted to be energized by an alternating voltage having a frequency within the range of approximately 100 Hz to 15,000 Hz to thereby cause the diaphragm to vibrate at a frequency determined by the applied alternating voltage in the presence of a magnetic field. A volume control permanent magnet is slidably mounted within the housing along a fixed predetermined path with respect to the coil and is connected to a manually operable lever means to be fixedly position at a predetermined physical location with respect to the coil along the predetermined path, whereby the volume of the audio output signal is determined by the physical position of the permanent magnet.