This basic circuit is from 1984 documentation. This circuit can be used as an efficient burglar alarm by simply choosing the sensor used appropriately. The behavior of the circuit can be analyzed as follows: when the input of the monostable (pin 2) is momentarily grounded by the switch used as a sensor, the output of the integrated (pin 3) is brought to the HI level, which corresponds to the presence of a voltage in the same order as the supply voltage; this voltage is insufficient to activate the relay, which can then supply a powerful alarm circuit.
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