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Wiring diagram
19.4 Circuit Explanation
As you already know, the passive buzzer needs different frequencies on the input to generate
different sounds.
We used low R5 (10k) and low C3 (100nF) with NE555(2) so we are going to get high frequency
on the output of NE555(2), but it is constant, to make it in 2 different sounds we used NE555(1)
and connect its output to pin 5 of NE555(2), so we have access to the internal voltage divider of
NE555(2) so we are going to change the output frequency of NE555(2) almost each 0.5
Second, and therefore the sound of the buzzer.
19.5 Example Picture
75
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