Small capacitance and long duration timer circuit diagram

The small capacitance and long duration timer circuit is shown in the figure below. When a delay time of several hours is required, two dual-input precision level detectors CA3098 are used, and there is no need to use large-capacity, low-leakage capacitors. If Rc=22MΩ, RD=100KΩ, and CTK only needs 16μF, you can get a timer with a delay time of 4 hours.

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