Abstract: The present invention relates to a condenser microphone whose body can be miniaturized while keeping a property and a sound quality comparable to those of a conventional condenser microphone. The condenser microphone includes a cylindrical body, a plurality of vibration plates which are formed into the shapes of squares and placed in parallel to a body axis line within the body, acoustic holes formed on a body side wall in a direction vertical to the vibration plates and back pole plates which are placed on a side opposite to the acoustic holes with the vibration plate between and face on the respective vibration plates at an interval of a micro gap. A potential of the back pole plate is varied according to a vibration of the vibration plate.

Abstract: The present invention relates to a condenser microphone whose body can be miniaturized while keeping a property and a sound quality comparable to those of a conventional condenser microphone. The condenser microphone includes a cylindrical body, a plurality of vibration plates which are formed into the shapes of squares and placed in parallel to a body axis line within the body, acoustic holes formed on a body side wall in a direction vertical to the vibration plates and back pole plates which are placed on a side opposite to the acoustic holes with the vibration plate between and face on the respective vibration plates at an interval of a micro gap. A potential of the back pole plate is varied according to a vibration of the vibration plate.

Abstract: An oscillator includes a converter, an oscillation transistor, a resistor, a capacitor and a primary coil of a transformer, and a rectifier includes a secondary coil of the transformer, resistors, capacitors, and a rectifying transistor. Control of the converter is carried out by the configuration of a capacitor, resistors and a transistor. A ripple filter includes a choke coil and ripple capacitors, and a converter activation part comprises a switch interlocked with a power supply switch and an activation diode. A ripple capacitor is also provided on the primary side of the converter. The battery is directly coupled to the primary side of the transformer.

Abstract: In a microphone, unnecessary radiation can be easily reduced with a simple construction.