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US-Style Siren: An Elektor Classic!
Many projects that flash, beep, move or do weird things have become Elektor classics and were published mainly in the Summer Circuits editions of the past. The recipe: inexpensive parts from the “old skool” bin and an immediate appeal to beginners (and — no offense — non-technical audiences). Here’s one: a siren-sound generator whose schematic is on a PCB crafted to ornament your desk.
Component list
Component List
[Illustration 220235-003-94]
[Illustration 220235-004-94]
Resistors (5%, 0.25 W)
R1,R9 = 2.2 kΩ
R2 = 470 Ω
R3 = 47 kΩ
R4,R8 = 22 kΩ
R5,R6,R7 = 18 kΩ
R10 = 3.3 kΩ
R11 = 1 kΩ
Capacitors
C1 = 100 µF, 16V
C2 = 2.2 µF, 16V
C3 = 10 µF, 16V
C4 = 47 µF, 16V
C5 = 22 nF, 5 mm pitch
C6 = 33 nF, 5 mm pitch
C7 = 470 µF, 16V
Semiconductors
T1,T2,T3,T4 = BC547
T5 = BC327
Miscellaneous
BAT1 = 2032 coin cell holder (Keystone 3003)
LS1 = speaker 8 Ω, 200 mW (Kingstate KSSG1708)
S1 = SP3T slide switch (C&K OS103011MA7QP1)
S2 = tactile switch, 6 mm pitch
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