| 摘要 |
PURPOSE:To protect the ear from the excessive sound when using the hearing aid or the like by varying the DC level to the excessive input signal and then actuating the switch circuit to stop the operation of the amplfier circuit when the difference increases between the DC level and the reference level. CONSTITUTION:The signal applied to input terminal 21 is amplified by amplifier circuit 22 and then delivered through output 23. In this case, part of the signal is converted to the DC level via converter circuit 24 and then compared through comparator circuit 25. In case the excessive signal is supplied, the DC level changes and the difference to the reference level increases, circuit 25 produces the control signal to actuate switch circuit 26. And as a result the operation of circuit 22 is stopped to limit the output signal. In such way, the output signal is stopped in case the excessive input is supplied, thus protecting the ear from the excessive sound when using the hearing aid or the like. |
