Schematic:
Notes:
The NE555 is
connected in the astable mode and uses only three
timing components (RA, RB, and Ct). A 0.01mF bypass capacitor is used on pin 5
for noise immunity. The operating restrictions of the astable
mode are few. The upper frequency limit is about 100kHz
for reliable operation, as a result of internal storage times. Theoretically,
it has no lower frequency limit, only that which is imposed by Rt and Ct limitations. The
frequency for the circuit can be calculated as:
f= 1.44____
(RA+2RB)Ct
=
1.44_______________
(4.7kW+2MW)(0.0047mF)
=
1.44________
9.42209 x 10e-3
=
152.8 Hz
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