14-10-2017, 11:12 AM
Circuit Description of the bag anti-theft alarm
The heart of this anti-theft alarm of the whole circuit is the operational amplifier IC CA3140 (IC1), configured as a comparator. The two inputs (inversion and non-inversion) are assigned to pins 3 and 2 of the operational amplifier, respectively, and the output is obtained from pin no 6. Here IC2 (timer IC NE555) is used as a monostable multivibrator. The timing component of the anti-theft burglar alarm is R5, VR1 and capacitor C2 with the value given in this circuit diagram allows the timer time to be approximately 1 minute.
For the audio section, IC3 is used as an alarm tone generator with a built-in oscillator. Finally, the output is obtained from pin 3 of IC3 and is amplified with transistor T1 to obtain the desired level and finally fed to the speaker for output.
LIST OF PARTS
Resistors (all ¼ watts, ± 5% carbon)
• R1, R2, R3 = 100 KΩ
• R4, R6 = 10 KΩ
• R5 = 10 MΩ
• R7 = 330 Ω
• R8 = 220 KΩ
• R9 = 1 KΩ
• VR1 = 10 MΩ
Condensers
• C1, C3 = 0.0047 μF
• C2 = 4.7 μF / 16 V
• C4 = 0.01 μF
Semiconductors
• IC1 = CA3140 (operational amplifier)
• IC2 = NE555 (IC timer)
• IC3 = UM3561 (complex ROM with built-in oscillator)
• T1 = BD139
• ZD1 = 3.3V 500mA
Diverse
• SW1 = ON / OFF switch
• L1 = speaker 8Ω 1W
• Mono connector, mono connector 8
The heart of this anti-theft alarm of the whole circuit is the operational amplifier IC CA3140 (IC1), configured as a comparator. The two inputs (inversion and non-inversion) are assigned to pins 3 and 2 of the operational amplifier, respectively, and the output is obtained from pin no 6. Here IC2 (timer IC NE555) is used as a monostable multivibrator. The timing component of the anti-theft burglar alarm is R5, VR1 and capacitor C2 with the value given in this circuit diagram allows the timer time to be approximately 1 minute.
For the audio section, IC3 is used as an alarm tone generator with a built-in oscillator. Finally, the output is obtained from pin 3 of IC3 and is amplified with transistor T1 to obtain the desired level and finally fed to the speaker for output.
LIST OF PARTS
Resistors (all ¼ watts, ± 5% carbon)
• R1, R2, R3 = 100 KΩ
• R4, R6 = 10 KΩ
• R5 = 10 MΩ
• R7 = 330 Ω
• R8 = 220 KΩ
• R9 = 1 KΩ
• VR1 = 10 MΩ
Condensers
• C1, C3 = 0.0047 μF
• C2 = 4.7 μF / 16 V
• C4 = 0.01 μF
Semiconductors
• IC1 = CA3140 (operational amplifier)
• IC2 = NE555 (IC timer)
• IC3 = UM3561 (complex ROM with built-in oscillator)
• T1 = BD139
• ZD1 = 3.3V 500mA
Diverse
• SW1 = ON / OFF switch
• L1 = speaker 8Ω 1W
• Mono connector, mono connector 8