Page 70 - Electronics Starter Kit_EN

When C3 gets charged, the green LED will turn OFF, and the yellow LED will light up. It is
connected to 5V, it is only in need to GND. When C1 and C2 get charged, the second part will
turn OFF, and the red LED will light up, and so on.

Note:
We added 2.2 uF capacitor(C2) in parallel with 10 uF capacitor(C1), to make the frequency of
NE555(1) lower than NE555(2), so the time of NE555(1) is bigger because F = 1 / T.
So we ensure when red LED is OFF, green LED and yellow LED will light up respectively, before
rel LED will light up again.

17.5 Example Picture

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