Arduino Based Lie Detector

Lie Detector (1)

We have previously posted the the project lie detector, now here is is also a lie detector using arduino. Here is a simple tutorial to build a simple lie detector which will give visual indication through LED arrangement whether the person speaks lie or truth. The project uses a arduino duemilanove or uno. So the project is based on arduino.
But our final circuit will be standalone circuit without attached arduino programmer.

Circuit Description:
Wiring diagram is very simple, we simply connected three LED to 3 different digital pins as
shown in diagram. A touch Plate is connected to an analog pin. Lie Detector (1)

Her is a simple version of software:

int redPin = 9;
int greenPin = 10;
int bluePin = 11;
int buzzerPin = 7;

int potPin = 1;
int sensorPin = 0;

long red = 0xFF0000;
long green = 0x00FF00;
long blue = 0x000080;

int band = 10;
// adjust for sensitivity
void setup()
pinMode(potPin, INPUT);
pinMode(sensorPin, INPUT);
pinMode(redPin, OUTPUT);
pinMode(greenPin, OUTPUT);
pinMode(bluePin, OUTPUT);
pinMode(buzzerPin, OUTPUT);

void loop()
int gsr = analogRead(sensorPin);
int pot = analogRead(potPin);
if (gsr > pot + band)
else if (gsr < pot – band)
void setColor(long rgb)

Arduino Based Lie Detector Schematic (1)

int red = rgb >> 16;
int green = (rgb >> 8) & 0xFF;
int blue = rgb & 0xFF;
analogWrite(redPin, 255 – red);
analogWrite(greenPin, 255 – green);
analogWrite(bluePin, 255 – blue);


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