BUILDING A LIE DETECTOR CIRCUIT


Hi guys! hope we have been busy, I know you’re thinking “is it possible to build a lie detector”, well to be really honest there is really no way to accurately tell if a person is lying or not using this circuit but we can build a fun circuit to show your friends based on the concept that people tend to sweat more when lying so we are going to build a circuit that detects the moisture on your hand and based on the sensitivity adjustment gives a response through either an LED or a piezo buzzer depending on what you want .we built our circuit using two LEDs ,one turns Green when true and the other red when false.so let’s get started but remember with great power comes great responsibility so use wisely!! COMPONENTS REQUIRED:

WORKING PRINCIPLE:


Operation of the circuit is a circuit of R1 and R2 divide the line voltage and probe used to measure the resistance of the skin, which is parallel with R2.So voltage drop across R2 is based on the resistance of the skin with is if the skin dry (people do not lie), the resistance of about 1 mega ohm to a strong drop across about 4.5 volt, but if the skin moist (liar), the resistance is less than 1 mega ohm to a voltage drop across less than 4.5 volts .It uses the pressure is on bias voltage to flow in Q1 – BC548, where Q1 and R3 buffer circuit to circuit. Voltage drop across R3 will be pressure to bias Q2 to conduct. There will be Q2 and Q3 (BC548) compared to the circuit voltage. That if the voltage at pin B of Q3 (voltage across VR1) is higher than the voltage at pin B of Q1 (voltage drop across R3), the pressure from the line probe to measure the resistance of the skin will allow. LED2 lit. show that the truth. In contrast, if a lie is the LED1 is illuminated.

SCHEMATICS:


The circuit we are going to build is going to be using a 9v battery to power the circuit
So, If you know how to read schematics, Well Done! you can easy make this without scrolling down even more. So, bye i guess? But the people who don't know how to read circuit diagrams and also If you have any questions about this project, just leave a comment below and we will try to answer it… And if you like our tutorials, please subscribe! you can check other tutorials for more fun and interesting projects you can get started with , feel free to share this if you know anyone else that might find it helpful! STAY CREATIVE!