●) Laser Security Alarm Circuit


Circuit Components

IC LM358
555 Timer IC
Laser light
150 Ohm, 10K Resistor
10 K POT
220uF capacitor
LDR
Breadboard
9 Volt Battery and Connector
LED

Working of Laser Security Alarm Circuit

In this circuit we have set reference voltages of
comparators by using potentiometer, we can say
this sensitivity of the circuit. Comparator is
configured in non-inverting mode. In this system we
have placed laser light and LDR facing each other,
so laser light continuously falls on LDR. Due to this
a potential difference generated across the non-
inverting pin of comparator, then comparator
compare this potential difference with reference
voltage and generate a digital output as HIGH.
Before this we have configured 555 timer in mono-
stable mode so we it required a LOW trigger pulse
at its trigger pin to activate buzzer and LED. So we
applied output of comparator at trigger pin of 555
timer. Even comparator’s output is HIGH when laser
lights falls on LDR so at this time buzzer and LED
are deactivated. When someone crosses the laser
light due to this LDR lost the laser light and
generates a different potential difference across the
same comparator terminal. Then comparator
generates an output as LOW. Due to this LOW
signal 555 timer gets a LOW trigger pulse and
activates buzzer and LED for a time periods that is
defined by R1 and C1 at 555 timer circuit.





Circuit Components

IC LM358
555 Timer IC
Laser light
150 Ohm, 10K Resistor
10 K POT
220uF capacitor
LDR
Breadboard
9 Volt Battery and Connector
LED

Working of Laser Security Alarm Circuit

In this circuit we have set reference voltages of
comparators by using potentiometer, we can say
this sensitivity of the circuit. Comparator is
configured in non-inverting mode. In this system we
have placed laser light and LDR facing each other,
so laser light continuously falls on LDR. Due to this
a potential difference generated across the non-
inverting pin of comparator, then comparator
compare this potential difference with reference
voltage and generate a digital output as HIGH.
Before this we have configured 555 timer in mono-
stable mode so we it required a LOW trigger pulse
at its trigger pin to activate buzzer and LED. So we
applied output of comparator at trigger pin of 555
timer. Even comparator’s output is HIGH when laser
lights falls on LDR so at this time buzzer and LED
are deactivated. When someone crosses the laser
light due to this LDR lost the laser light and
generates a different potential difference across the
same comparator terminal. Then comparator
generates an output as LOW. Due to this LOW
signal 555 timer gets a LOW trigger pulse and
activates buzzer and LED for a time periods that is
defined by R1 and C1 at 555 timer circuit.


Comments

  1. Unknown23 August 2017 at 15:31

    The laser security alarm circuit has a simple operation mechanism although it is made up of several components. This post will help students and researchers to learn how the circuit operates. Thanks for sharing the information with us and students in this forum can visit our writing site and access Nursing School Assignment Help.

    ReplyDelete
  2. Jhon Walker30 September 2019 at 17:19

    Yes, i totally agreed with your article that wireless security system is better than wired. Thanks for sharing such nice information with us. I am looking for better option for smart burglar alarm to secure my home, property and family form thieves. Please gives your suggestion with price range.

    ReplyDelete

Post a Comment

Popular posts from this blog

●) 12v DC to 220v AC converter

Image
12v DC to 220v AC converter:- Principle Behind this Circuit:- The basic idea behind every inverter circuit is to produce oscillations using the given DC and apply these oscillations across the primary of the transformer by amplifying the current. This primary voltage is then stepped up to a higher voltage depending upon the number of turns in primary and secondary coils. Also get an idea about 12V to 24V DC Converter Circuit Inverter circuit Using Transistors A 12V DC to 220 V AC converter can also be designed using simple transistors. It can be used to power lamps up to 35W but can be made to drive more powerful loads by adding more MOSFETS. The inverter implemented in this circuit is a square wave inverter and works with devices that do not require pure sine wave AC. Components required:- 12v Battery MOSFET IRF 630 -2 2N2222 Transistors 2.2uf capacitors-2 Resistor 680 ohm-2 12k-2 12v-220v center tapped step up transformer. 2N2222 Datasheet
Read more

●) Fire alarm

Image
Components required: Power supply Resistors (1kΩ) Potentiometer (10KΩ) Capacitor (10µF, 16V) BC548 transistor High resistance thermistor (NTC) Diode (1N4001) 6V Buzzer Working of fire alarm circuit Working is based on the switching property of transistor. The thermistor and R1 forms a potential divider network which drives the transistor. The heart of this circuit is a thermistor. Thermistors are low-cost, easily-available temperature sensors widely used for uncomplicated temperature measurements. Thermistors are temperature sensitive resistors. When temperature increases resistance offered by the thermistor decreases and vice versa. At normal temperature, the resistance of the thermistor is around 10kΩ. All resistors vary with temperature, but the semiconductor materials used for thermistors are especially sensitive to temperature. The transistor is turned ON by the voltage drop across the resistor R1. Consider the temperature of the atmosphere is around
Read more