Lick 'O' Meter

idiot.io 

Lick’O’Meter is A Simple And Very Interesting Resistive Touch Circuit .

we’ve been Developing The Lick’O’Meter Circuit since 2015 And Teaching it in our basic Electronics workshops, Electrodible – Smart candy Workshop and various projects. 

 

 

 

This is the most basic type of touch switch, in its simplest form. The operation is simple. A transistor is used as a switch. 

The resistor keeps the base to ground when no electrode is touched, so it does not float. 

If one of the electrodes is touched, nothing will happen. But if both electrodes are touched together,

then a small amount of current will flow through the skin to the gate of the transistor. 

The transistor will then go from cut-off to saturation, and current will flow from the D S region to the LOAD.

 

There are numerous different ways to implement a resistance touch switch, with transistors, with 555, with 741, with CMOS and many more. 

The idea is always the same though: Two electrodes are used for the touch plates. Current flow from the human skin from one electrode to the other, 

which finally stimulates an amplifier or another current sensitive part. 

 

 (http://www.pcbheaven.com/wikipages/How_a_Touch_Button_works/)