| 摘要 |
PURPOSE:To eliminate a difference between timer time and a scale even if the value of a variable resistance for setting the timer time has an error, by varying a threshold voltage to be applied to a timer IC. CONSTITUTION:When a trigger pulse is applied to the trigger signal input terminal TR of a timer IC1, charging to a capacitor C is started through a variable resistance VR and the terminal voltage of the capacitor C rises according to an expontentional function. When the resistance value of the resistance VR is greater than a designed value, the time constant increases, so that time T1 up to when the terminal voltage reaches a threshold voltage VTh becomes longer than timer time T0. When less, the time T2 up to when the voltage reaches the voltage VTh becomes shorter than the time T0. In this case, a variable resistance VRt for threshold voltage adjustment is adjusted according to the value of the resistance VR to increase or decrease the value of the voltage VTh to be applied to a threshold voltage terminal Th. |
