This article was originally included, one of my books on espionage.
The siren that we give in figure 1 is for circuits operating with 6 tp 12V voltages and drives a loudspeaker with good power.
P1 adjusts the cadence of the sound, while P2 adjusts its pitch. The PTP42 power transistor must be mounted on a heat radiator while the speaker must be of good quality for greater sound yield.
It should preferably be mounted in a small acoustic box.
SEMICONDUCTORS
CI-1 and CI-2 - 555 - integrated circuits
Q1 - BC547 or equivalent - general purpose NPN transistor
Q2 - BD433 - NPN power transistor
RESISTORS
P1 and P2 - 100 k - trimpots
R1 and R2 - 10 k - resistors (brown, black, orange)
R3 - 1k - resistor (red straight brown)
R4 and R5 - 4.7 k - resistors (yellow, violet, red)
R6 - 470 ohm - resistor (yellow, violet, brown)
CAPACITORS
C1 - 10 uF x 16V - electrolytic capacitor
C2 - 100 nF - ceramic or polyester capacitor
CS - 220 uF x 16V - electrolytic capacitor
SEVERAL
FTE - 4 or 8 ohm - heavy speaker
Printed circuit board, integrated sockets, Q2 heat radiator, wired speaker etc.
