| 摘要 |
PROBLEM TO BE SOLVED: To provide a microphone apparatus for connecting a plurality of electret condenser microphones, in parallel with a load (output transformer) that prevents DC magnetization of the transformer. SOLUTION: The microphone apparatus provided with the plurality of electret condenser microphones, each including a microphone capsule 11 and a FET 12 acting as an impedance converter and each connected in parallel with the load, includes the output transformer 21 used for the load; and a current mirror circuit 24, a primary winding 22 of the output transformer 21 is provided with a center tap 22c, the drains of the FETs 12 are connected in parallel with a single winding part 22a of the primary winding 22, the sources of the FETs 12 are connected in parallel with a current input side of the current mirror circuit 24, the other winding part 22b of the primary winding 22 is connected to the current output side of the current mirror circuit 24, and a DC power supply Vcc is connected to the center tap 22c via a load resistor RL. COPYRIGHT: (C)2006,JPO&NCIPI |
