NE555/SA555/NA555PRECISION TIMERSTypical Applications Characteristics (cont.)Missing Pulse Detector The circuit shown in Figure 7 can be used to detect a missing pulse or abnormally long spacing between consecutive pulses in a train of pulses. The timing interval of the monostable circuit is retriggered continuously by the input pulse train as long as the pulse spacing is less than the timing interval. A longer pulse spacing, missing pulse, or terminated pulse train permits the timing interval to be completed, thereby generating an output pulse as shown in Figure 8.