The following NE555 datasheet includes another 555 Precision Timers series which is produced by Texas Instruments such NA555, SA555, and SE555. In the datasheet you can find application information for designing monostable operation, astable
operation, missing-pulse detector, frequency divider, pulse-width
modulation, pulse position modulation and sequential timer using the
NE555 series with circuit diagram for each application.
The figure above shows you the NE555 Missing-Pulse Detector Circuit Diagram.
According to the datasheet, this circuitry design can be used to detect
a missing pulse or abnormality long spacing between consecutive pulses
in a train of pulses. When the
pulse spacing is less than the timing interval, the timing interval is
retriggered continuously by the input pulse train.
We can make the spacing of pulse a little bit longer, missing the pulse or terminating pulse train
to complete the timing interval and thereby generating a specific
output pulse (as shown in the datasheet). Please complete read of NE555 Missing-Pulse Detector Circuit Diagram in the NE555 Datasheet (source: ti.com).