# How to use Capacitive Touch Sensor in Proteus Schematic Circuit Diagram

Hello friends, I hope you all are fine and enjoying. Today i am going to share my new project’s tutorial which is How to use Capacitive Touch Sensor in Proteus ISIS. It is a very interesting project, and we will be using a 555 Timer while designing this project. If you recall our previous project tutorial which was Angle Control of Servo Motor using 555 Timer in Proteus ISIS, in which 555 timer was generating PWM and was controlling the rotating angle of servo motor.

Now in this project, we have a little different context and now we will be using a 555 Timer in collaboration with Capacitive Touch Sensor. First of all, lets have a little introduction of Capacitive Touch Sensor. Well, if we talk broadly then, in Electrical Engineering Capacitive Touch Sensing is a Technology used in Capacitive Coupling. Capacitive Coupling is a technology which takes Human Body’s Capacitance as an input and it measures anything which has a potential difference or  which is conductive or any static object which has a dielectric difference from that of air. While designing this technology, one side of the insulator is coated with the conductive material and a very small voltage is applied to this conductive layer. Now after applying the voltages to the conductive layer, a uniform electrostatic field is formed. After that if any conductor (suppose human finger) will come within the vicinity of this field or it touches the other non coated layer of the insulating material then a capacitor will be dynamically formed and if potential difference between both bodies is HIGH then the current will start to flow. That was a little introduction of Capacitive Touch Sensor, and now lets be practical and move towards the Hardware of the Above described tutorial.

You can download the complete simulation of above described project by simply clicking on the link given below:

https://www.theengineeringprojects.com/Examples/HowtouseCapacitiveTouchSensorinProteusISIS.rar

#### How to use Capacitive Touch Sensor in Proteus

• In this project, we are using 555 Timer in collaboration with Capacitive Touch Sensor. A 555 timer is an 8 pin IC. Pin # 6 is called threshold pin and for 555 timer threshold level is 5 volts.
• So, 555 timer will trigger above 5 volts and it will generate output which can be collected from pin # 3 represented as ‘Q’ which is output pin of 555 timer.
• While moving toward the simulation of project, first of all place all the components in the proteus workspace, as shown in the image given below:

• First of all we have place Capacitive Touch Sensor and after that we have placed a NPN transistor, then 555 Timer will come and at the output of 555 Timer we have added a LED. The complete circuit diagram ready for simulation is shown in the image given below:

•  As long as the finger is out of the vicinity of the electrostatic field, no potential difference occurs and the LED remains in the OFF state.
• Now if we move the finger towards Capacitive Touch Sensor, then and when the potential difference reaches up to 0.6 volts, then 555 triggers and it generates output voltages across LED which are 5 volts but in some cases voltages are lost due to series connected resistances. This phenomenon is shown in below image:

• Now if we further move the finger and take it completely near the sensor, then at this point max potential difference will occur between both point (finger and conductive layer). An important thing to note here is that, we have change the location of our interrupt ( finger) but, same voltages are appearing across LED which are 4.91 volts in this case. It can also seen in the figure given below:

• Now, if we summarize the whole project, then we have seen that the movement of finger is in fact controlling our output. When the finger was out of vicinity of the sensor, then LED was OFF. When we moved the finger in forward direction and came in the vicinity of Electrostatic field, then Sensor gives signal to 555 Timer and Timer makes LED to glow.
• Here’s a video demonstrating Capacitive Touch Sensor in Proteus ISIS.

#### Applications Of Capacitive Touch Sensor

Capacitive sensing touchscreens are now a days commonly used in Digital Audio Players, Mobile Phones and Tablet Computers. Capacitive touch sensors also have the ability to replace Mechanical Buttons. Back in 1928 Russians invented a music instrument known as “Theremin” , in which The Instrument Player was able to control the volume and pitch of the sound without physically touching the instrument. Capacitive Touch Sensors are of basic level but they are back bone of large industrial projects and are widely used in designing some other sensors like:

1. Position sensor.
2. Humidity sensor.
3. Fluid or Water level sensor.
4. Proximity sensor etc..

Alright friends, that’s all for today, I hope I have conveyed some knowledge and helped you people in some way. If you have some queries, then ask in comments. Subscribe us via email to get these tutorials straight in your inbox. Till next tutorial, take care and be safe !!! ?

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