把信号加到RC低通滤波器上并测量电容器上的电压,就可以确定多周期信号的平均值。然而,当知道信号每个周期的平均值时,对确定多周期信号的平均值将是很有帮助的。图1所示的电路,使用廉价的组件便能完成这一任务。图中,LM311构成斯密特触发器用来整形缓慢上升的信号并驱动接成触发线路的IC_2(4013)。输出Q(脚1)在整个一周内保持高电平,使IC_3通过R_2C_2记下这一周内的平均值。当第二周期开始时,4013翻 Adding a signal to the RC low-pass filter and measuring the voltage across the capacitor determines the average of the multi-period signal. However, knowing the average of each period of the signal will be helpful in determining the average of the multi-period signal. The circuit shown in Figure 1 uses inexpensive components to accomplish this task. In the figure, the LM311 constitutes a Schmitt trigger for shaping the slowly rising signal and driving IC_2 (4013) into the trigger line. Output Q (pin 1) stays high for the entire week, allowing IC_3 to write down the average for the week by R_2C_2. When the second cycle begins, 4013 turns