This circuit has an adjustable output timer that will re-trigger at regular intervals. The output period can be anything from a fraction of a second to half-an-hour or more – and it can be made to recur at regular intervals of anything from seconds to days and beyond.
The output section is a simple Monostable Circuit. When Pin 6 of the Cmos 4001 is taken high – the monostable triggers – and the relay energizes. It will remain energized for a period of time set by C1 & R3.
With the values shown – R3 will provide output periods of up to about 30-minutes. However, you can choose component values to suit your requirements. For example, if you reduce R3 to 1meg – and C1 to 4.7uF – the maximum output period is between 3 and 5 seconds. Owing to manufacturing tolerances – the precise length of the time period available depend on the characteristics of the actual components you’ve used.
The Cmos 4060:
The Cmos 4060 is a 14-bit binary counter with a built-in oscillator. The oscillator consists of the two inverters connected to Pins 9, 10 & 11 – and its frequency is controlled by R7. The output from the oscillator is connected internally to the binary counter. While the oscillator is running – the IC counts the number of oscillations – and the state of the count is reflected in the output pins.
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