Manual

-109-
T
his siren gives off alternating high and low sounds.
Slide the switch to position B and construct the
c
ircuit. After you complete the wiring and slide the
switch to position A, the power turns on and the
speaker creates the sound of a two-pitch siren.
This siren is made up of two astable multivibrators.
IC 2 provides the normal beep sound. IC 1 produces
the signal that alters the pitch of its sound at regular
intervals.
Let’s execute a small experiment now. The siren
gives out an intermittent beep instead of the two-
pitch sound once you detach the 22kW resistor. Can
you decipher why? The IC 1 interrupts the siren
sound produced by IC 2.
N
otes:
EXPERIMENT #90: CRISIS SIREN
Wiring Sequence:
o 1-29
o 2-30
o 3-116
o 5-83-70-108-112-121
o 85-63-131
o 64-90-92-115
o 65-107-89
o 66-82-84-86-91
o 81-94-88-67
o 93-68-111
o 69-80-87
o 79-119-124
o 122-132
Schematic
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