دائرة تنبيه بوجود أشعة فوق بنفسجية Infra Red Bug

دائرة تنبيه بوجود أشعة فوق بنفسجية Infra Red Bug

دائرة تنبيه بوجود
أشعة فوق بنفسجية Infra Red Bug

Infra Red
BugThis circuit can be
used to detect the presence of modulated infrared signals in its vicinity from
any electronic source, for instance, an IR handheld remote controller. It can
also be used for testing IR burglar alarm systems. Fig. 1 shows the circuit of
the infrared bug. Besides the power supply (one 9V PP3/6F22 compact battery
pack), it consists of an infrared signal
detector-cum-preamplifier
followed by a melody generator and a tiny audio
amplifier. The circuit, in principle, converts the IR signal pulse trains into
noticeable aural notes. S1 is used to switch on/off mains power and LED1
indicates power ‘on.’ Resistor R4 and zener diode ZD2 form a low-current voltage
stabilizer for providing steady 5.1V DC to the small signal preamplifier
circuit. IR LED1 is the main sensing element.
The IR signal detected by IR LED1 is
amplified by npn transistors T1 and T2. The amplified signal is fed to the
melody generator via resistor R5. The output of the melody generator is fed to
LM386 low-power audio amplifier (IC2) via variable resistor VR1, which works as
the volume control. The loudspeaker sounds to indicate the presence of IR signal
near the circuit.
IC
LM386 is wired as a minimum-parts amplifier with a voltage gain of ‘20,’ which
is sufficient for this application. Capacitor C3 is used for decoupling of the
positive rail and the R-C combination network comprising C4 and R7 bypasses high
frequency to ground. The circuit can be easily wired on a small vero board or
any general-purpose PCB. Pin configurations of IC LM386, transistor BC547 and
melody generator UM66 are shown in Fig. 2. A miniature metallic cabinet may be
used for enclosing the gadget.

[ندعوك للتسجيل في المنتدى أو التعريف بنفسك لمعاينة هذه الصورة]

دائرة تنبيه بوجود أشعة فوق بنفسجية Infra Red Bug

دائرة تنبيه بوجود أشعة فوق بنفسجية Infra Red Bug

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