Linear Monostable Converts Capacitive Transducer Measurements into Pulse Train (.PDF Download)

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The circuit in Figure 1 allows you to convert capacitance into a pulse train by using a constant current source and a linear monostable formed by two NAND-gate chips (74HC132). The circuit also provides two pulses to control external counter functions such as Latch and Reset, which are normally required by digital counters and latches when driving a display. Applications for the monostable include instrumentation circuits when the need arises to convert a transducer’s capacitance measurement (such as relative humidity), into a pulse train.