Introduction
With the arising time, it is getting difficult to catch or find the criminal using those old methods of investigation. All the criminal-minded people know about the tricks of getting overly from those crimes. In that case, the only method is to use the technology for that purpose. So, engineers have made lie detector circuits to detect the liar. So, we have decided that in this tutorial, we are going to “Lie Detector Circuit”. However, this is just a small prototype kind of circuit that you can use to trick or prank your friends. The circuit uses a few easily available components and can be made by anyone having little knowledge of electronics.
Hardware Required
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | Transistor | BC548 | 3 |
| 2. | Variable Resistor | 47KΩ | 1 |
| 3. | LED | – | 2 |
| 4. | Jumper Wire | – | 1 |
| 5. | Capacitor | 0.1μF | 1 |
| 6. | Resistors | 1MΩ, 10KΩ, 47KΩ, 470Ω | 2, 1, 1, 1 |
| 7. | Battery | 9v | 1 |
| 8. | 2-Pin Connector | – | 1 |
Circuit Diagram
Working Explanation
This lie detector circuit checks the anxiety level of a person. Its functions are based on variations of skin resistance. For instance, if a person when lies during questioning or conversation his anxiety level get to rise and it causes him to sweat. And, when he sweats, moisture occurs on his hands & fingers. So, by using this lie detector circuit you can detect those moments of anxiety. LEDs’ glow depends on the moisture and conductivity of the skin. When a person lies red LED glows, otherwise a green one gets glows.
Application and Uses
- Military, police, and crime control departments can use this circuit to catch criminals.
