| 摘要 |
PURPOSE:To detect a pulse signal surely even if the width of the pulse width transferred through a photocoupler is very narrow, by inserting a diode between the input and the output of an operational amplifier. CONSTITUTION:When a pulse signal Pi is applied to a light emitting diode D11 of a photocoupler 11, this pulse signal Pi is transferred to both ends of a load resistance RL through a transistor Q11. Then, this signal is applied to the input terminal of an inversion amplifier 13 through a capacitor C11. A negative feedback resistance Rf and a diode D12 are provided between the input terminal and the output termianl of the inversion amplifier 13, and a threshold voltage Vth of the amplifier 13 is always set near the peak value of the voltage vetween both ends of the load resistance RL automatically by the function of the diode D12. Consequently, a pulse output is obtained surely in an output terminal 12 even if the width of the input pulse signal Pi is very narrow. |
