Luggage Security Alarm
SummaryWhen we travel in bus or train we take many important things and always fear that somebody might steal our luggage. To safe our luggage we generally lock our luggage using old way with chain and lock arrangement. But we are still in tension that somebody may cut the chain and take away our precious material. To solve this problem here is a simple circuit for you based on NAND gate. In this when somebody tries to steal our luggage it will give a warning alarm and with the help of this you can travel in train and buses without fear in night also as it can give you the audio visual indication connected to the relay.
Another application may be you can use this circuit in home to prevent the attempt of burglary in your home using this alarm circuit. When somebody tries to open the door of your home loop breaks and alarm start sounding.
Description
The circuit is build around CD4011 with the help of some more components like resistor, Capacitor, transistor, relay and can be used to protect your valuables from burglary using this simple circuit. It generates warning beep when somebody attempts to open the lock as a result wire loop will break and alarm is generated.
To understand the working you should know about the truth table of NAND gate are as follows-
Input
| Output | |
A
|
B
| |
0
|
0
|
1
|
0
|
1
|
1
|
1
|
0
|
1
|
1
|
1
|
0
|
In NAND gate we will get output when any of the input signals go low and if both are high we will not get output in that case.
Working of the circuit is very simple when we will get output is depending on the voltage on pin 5. When power supply is connected to the circuit voltage at pin 5 is zero as loop is intact. Therefore voltage at pin 4 is high which is connected to pin 1 and 2 which is also high. As you can see from truth table if both the inputs are high output is low therefore we will receive low at pin3 of gate 1 which is again connected to pin 12 and 13 making them also low as a result pin 11 goes high making pin 8 and 9 also high and voltage at pin 10 is low as a result transistor connected to it through resistor will not energize the base of it and we will not receive the alarm. Means our luggage is safe.
Now imagine somebody tries to take your luggage therefore loop connected to it breaks. When loop breaks pin 5 and 6 goes high and reverse action take place as we told you above as a result pin 10 become high transistor start conducting and we will receive an alarm.
And this alarm will not go off until we intact the loop again. In this circuit we can use battery from 6-15V depending the rating of the relay you are using. If you want you can also connect the buzzer directly without using relay. We are using it so that if you want to connect the alarm which will be operated by AC then you must use relay. We are using a diode with the relay because any reverse-voltage spikes will be short-circuited at source and they can do any damage.
| Components | |
| IC | |
| IC1(CD4011) |
1
|
| Resistor | |
| R1(1K) |
1
|
| R2(4.7K) |
1
|
| Capacitor | |
| C1(.1uF) |
1
|
| Miscellaneous | |
| Relay |
1
|
| T1(BC547) |
1
|
| D1(1N4007) |
1
|
