Electronics Online

This simple lie detector circuit implementing human skin conductivity which varies according to the condition of the emotions. You can easily created with just a few minutes and cheap.

This is how simple lie detector work : The circuit uses an oscillator that has a frequency based on C1, R2, and skin resistance at the touch pad. Because C1 and R2 value is fixed, only the skin resistance at the touch pad that can change the tone oscillator. To maintain oscillation, the C1 provides some output from Q2 back to the input of Q1 through R1.

This is another Running LED circuit from Radio Electronics. The circuit is very simple consists of three main components, Timer 555, 7493 Binary Counter, 4 line to 16 line decoder 74 154.

How do this Running LED circuit work : 555 timer generates a rapid circuit pulses when the switch S1 is open. Pulses are counted in groups of 16 and converted into a binary code by 7493 which is then given to 74154 (decoder 1 to 16). 

This is a simple 5volt power supply circuit using ic regulator type 7805. This circuit can be paired with Running LEDs circuit II in the Fun circuit category or even digital ic circuits. Input ranges from 8 Volts to 18 Volts DC. This circuit has a LED as an indication, if the power supply turns on.