Laser Beam Alarm

An alarm that triggers a siren sound an police lights when the beam of light is interrupted.

Mar 23, 2019

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33957 views

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28 respects

home automation

security

Components and supplies

Resistor 330 ohm

Jumper wires (generic)

Photo resistor

Buzzer

Breadboard (generic)

Laser pointer

5 mm LED: Red

Pushbutton

Arduino UNO

Apps and platforms

Arduino IDE

Project description

Code

Laser Alarm

c_cpp

Just adjust the sensivity to match your laser pointer's power. To reset the alarm just push the button.

1/*
2A laser pointer is needed to make a light beam that will be detected  by the ldr
3Make Sure you line up the beam and the ldr properly
4*/
5const  int sensivity = 400;  // 0-1023 a lower value means a more powerful laser
6
7#define  ldr A0
8#define redLed 7
9#define blueLed 8
10#define buzzer 9
11#define buttonPin  A2
12
13
14int buttonState;
15int state = 0;
16
17
18void setup() {
19  alarmOFF();
20  Serial.begin(9600);
21  pinMode(redLed, OUTPUT);
22  pinMode(blueLed, OUTPUT);
23  pinMode(buzzer, OUTPUT);
24}
25
26void loop() {
27  int light = analogRead(ldr);
28  int button = analogRead(buttonPin);
29  Serial.print("button = ");
30  Serial.print(button);
31  Serial.print("\
32");  
33  Serial.print("light = ");
34  Serial.print(light);
35  Serial.print("\
36");  
37  Serial.print("state = ");
38  Serial.print(state);
39  Serial.print("\
40"); 
41  Serial.print("\
42");  
43  if (button >= 1020)  {
44    state = 0;
45  }
46  if (light > sensivity) {
47    state = 1;
48  }
49  if ((light <= sensivity) && (state == 0)) {
50    alarmOFF();
51  }
52  if  (state == 1) {
53    alarmON();
54  }
55}
56
57
58void alarmON() {
59  tone(buzzer,  1760);
60  digitalWrite(redLed, HIGH);
61  digitalWrite(blueLed, LOW);
62  delay(500);
63  tone(buzzer, 1319);
64  digitalWrite(blueLed, HIGH);
65  digitalWrite(redLed,  LOW);
66  delay(500);
67}
68
69void alarmOFF() {
70  noTone(buzzer);
71  digitalWrite(redLed,  LOW);
72  digitalWrite(blueLed, LOW);
73}

/*
A laser pointer is needed to make a light beam that will be detected  by the ldr
Make Sure you line up the beam and the ldr properly
*/
const  int sensivity = 400;  // 0-1023 a lower value means a more powerful laser

#define  ldr A0
#define redLed 7
#define blueLed 8
#define buzzer 9
#define buttonPin  A2


int buttonState;
int state = 0;


void setup() {
  alarmOFF();
  Serial.begin(9600);
  pinMode(redLed, OUTPUT);
  pinMode(blueLed, OUTPUT);
  pinMode(buzzer, OUTPUT);
}

void loop() {
  int light = analogRead(ldr);
  int button = analogRead(buttonPin);
  Serial.print("button = ");
  Serial.print(button);
  Serial.print("\
");  
  Serial.print("light = ");
  Serial.print(light);
  Serial.print("\
");  
  Serial.print("state = ");
  Serial.print(state);
  Serial.print("\
"); 
  Serial.print("\
");  
  if (button >= 1020)  {
    state = 0;
  }
  if (light > sensivity) {
    state = 1;
  }
  if ((light <= sensivity) && (state == 0)) {
    alarmOFF();
  }
  if  (state == 1) {
    alarmON();
  }
}


void alarmON() {
  tone(buzzer,  1760);
  digitalWrite(redLed, HIGH);
  digitalWrite(blueLed, LOW);
  delay(500);
  tone(buzzer, 1319);
  digitalWrite(blueLed, HIGH);
  digitalWrite(redLed,  LOW);
  delay(500);
}

void alarmOFF() {
  noTone(buzzer);
  digitalWrite(redLed,  LOW);
  digitalWrite(blueLed, LOW);
}

Laser Alarm

c_cpp

Just adjust the sensivity to match your laser pointer's power. To reset the alarm just push the button.

1/*
2A laser pointer is needed to make a light beam that will be detected   by the ldr
3Make Sure you line up the beam and the ldr properly
4*/
5const   int sensivity = 400;  // 0-1023 a lower value means a more powerful laser
6
7#define   ldr A0
8#define redLed 7
9#define blueLed 8
10#define buzzer 9
11#define buttonPin   A2
12
13
14int buttonState;
15int state = 0;
16
17
18void setup() {
19  alarmOFF();
20   Serial.begin(9600);
21  pinMode(redLed, OUTPUT);
22  pinMode(blueLed, OUTPUT);
23   pinMode(buzzer, OUTPUT);
24}
25
26void loop() {
27  int light = analogRead(ldr);
28   int button = analogRead(buttonPin);
29  Serial.print("button = ");
30  Serial.print(button);
31   Serial.print("\
32");  
33  Serial.print("light = ");
34  Serial.print(light);
35   Serial.print("\
36");  
37  Serial.print("state = ");
38  Serial.print(state);
39   Serial.print("\
40"); 
41  Serial.print("\
42");  
43  if (button >= 1020)   {
44    state = 0;
45  }
46  if (light > sensivity) {
47    state = 1;
48  }
49   if ((light <= sensivity) && (state == 0)) {
50    alarmOFF();
51  }
52  if   (state == 1) {
53    alarmON();
54  }
55}
56
57
58void alarmON() {
59  tone(buzzer,   1760);
60  digitalWrite(redLed, HIGH);
61  digitalWrite(blueLed, LOW);
62  delay(500);
63   tone(buzzer, 1319);
64  digitalWrite(blueLed, HIGH);
65  digitalWrite(redLed,   LOW);
66  delay(500);
67}
68
69void alarmOFF() {
70  noTone(buzzer);
71  digitalWrite(redLed,   LOW);
72  digitalWrite(blueLed, LOW);
73}

/*
A laser pointer is needed to make a light beam that will be detected   by the ldr
Make Sure you line up the beam and the ldr properly
*/
const   int sensivity = 400;  // 0-1023 a lower value means a more powerful laser

#define   ldr A0
#define redLed 7
#define blueLed 8
#define buzzer 9
#define buttonPin   A2


int buttonState;
int state = 0;


void setup() {
  alarmOFF();
   Serial.begin(9600);
  pinMode(redLed, OUTPUT);
  pinMode(blueLed, OUTPUT);
   pinMode(buzzer, OUTPUT);
}

void loop() {
  int light = analogRead(ldr);
   int button = analogRead(buttonPin);
  Serial.print("button = ");
  Serial.print(button);
   Serial.print("\
");  
  Serial.print("light = ");
  Serial.print(light);
   Serial.print("\
");  
  Serial.print("state = ");
  Serial.print(state);
   Serial.print("\
"); 
  Serial.print("\
");  
  if (button >= 1020)   {
    state = 0;
  }
  if (light > sensivity) {
    state = 1;
  }
   if ((light <= sensivity) && (state == 0)) {
    alarmOFF();
  }
  if   (state == 1) {
    alarmON();
  }
}


void alarmON() {
  tone(buzzer,   1760);
  digitalWrite(redLed, HIGH);
  digitalWrite(blueLed, LOW);
  delay(500);
   tone(buzzer, 1319);
  digitalWrite(blueLed, HIGH);
  digitalWrite(redLed,   LOW);
  delay(500);
}

void alarmOFF() {
  noTone(buzzer);
  digitalWrite(redLed,   LOW);
  digitalWrite(blueLed, LOW);
}

Downloadable files

Laser Alarm Schematic

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