This circuit turns on LED with the contact of your finger! Many times we want positive actions to be completed with contact as an alternative to pressing a button. This simple circuit uses minimal components. Step-by-step directions on how to build the circuit are in the video beneath.
Hardware Components
The following components are required to make the Touch Switch Circuit
| S. No | Component | Value | Qty |
|---|---|---|---|
| 1. | Breadboard | – | 1 |
| 2. | Metal Strips/Hard Copper Wires | – | 2 |
| 3. | NPN Transistor | BC547 | 2 |
| 4. | Resistors | 270 ohm, 100K ohm | 1,1 |
| 5. | LED | 5mm | 1 |
| 6. | Battery | 9v | 1 |
BC547 Transistor Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of BC547 Transistor
Touch Switch Circuit
Working Explanation
The circuit will also work with simply one transistor, but the LED does not glow vibrant enough. So we have used two. A tiny electric current flows through the pores and skin when the end touch conductors are touched. This tiny current is amplified in magnitude by using the first and second transistors and it ultimately passes through the LED. Refer to the circuit diagram for a better understanding.
Application
We can modify this basic circuit for so many applications like adding a relay at the output to control ac appliances with a touch button.
