Sequential timer circuit diagram composed of 555 chip

Feeding the first half output of the 556 dual timer to the second half input via a 0.001µF coupling capacitor gives a total delay equal to the sum of the individual delays. Momentarily grounding pin 6 starts the first half of the timer. After the time interval determined by 1.1R1C1, the second timer starts delaying, and its value is determined by 1.1R2C2.

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