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Touch Switch: What is it and how to create a touch switch

A touch switch refines an electronic device’s usability. While providing added functionality, these particular components offer a unique experience. That’s because it gives more control over compatible devices. Although not a new technological development, the touch switch still rises in popularity today.

At WellPCB, we strive to help you gain a deeper insight. After reading this article, you will discover that three types of touch switches exist today, understand their capabilities, how they work, and their applications. Want to create one yourself? We also detail steps you can take towards designing a touch switch! So continue reading to acquire more knowledge on this technology.

1. What is the Touch Switch?

 While a mechanical switch controls the circuit through applied pressure, a touch switch slightly differs. The touch switch, a tactile sensor, provides the user with more control over any compatible electronics.  Whereas regulators need more applied pressure to close a circuit and operate, the touch switch requires a small press. These work via a human’s conductive properties. That’s because a human body serves as a conductor for the touch switch, which detects conductive elements to function. So when you tap it, the capacitance decreases, forcing the circuit to close.

A plastic mechanical switch

(A plastic mechanical switch.)

A manufacturer or user can modify a touch switch regarding features, appearance, and even performance. For example, doing so allows them to alter an LED light’s brightness and color in response to pressure levels.

2. Touch switch applications

A touch electrical switch

(A touch electrical switch.)

Touch switches can operate while mounted on surface panels and displays, such as acrylic, plastic, and glass. It makes them popular in everyday applications for home and office installments.  

Furthermore, a multi-purpose keypad consists of multiple touch switches organized in series on a panel. As a result, users gain more control over varying applications. Additionally, a touchscreen display contains a touch switch array.

A smart device’s display contains an array of touch switches

(A smart device’s display contains an array of touch switches. )

Popular applications include electronic devices, such as lamps, a modern wall touch switch, and computer terminals. 

You can also implement these in audio and broadcasting equipment. A smart switch notably offers automatic activation for your home needs.

Laptops, smartphones, lighting circuits, automation equipment, and medical equipment also benefit from touch switch integration. Additionally, a control touch switch allows you to time certain features in your connected devices.

3. How Touch Switches Work

A simple drawing that shows how the touch switch functions

(A simple drawing that shows how the touch switch functions.)

A touch switch works best with applied force, pressure, or touches. While this happens, the connection opens or closes in response to magnetism, light, electricity, or a chemical/mechanical factor. In addition, sometimes input/output functionalities allow it to function. For instance, a virtual keyboard utilizes touch switches. In effect, pressure applied to specific keys triggers a response, which outputs to the system.

https://www.shutterstock.com/zh/image-vector/touch-screen-virtual-keyboard-glowing-keys-152476694

(Touch switches in a virtual keyboard send instructions to a computer.)

Moreover, smartphone screens contain complex touch switches integrated with unique features. Specifically, that includes haptic feedback or a capacitive sensor; however cablesrything still follows the same operational approach despite the sensing technologies.

A smartphone screen contains complex touch switches

(A smartphone screen contains complex touch switches.)

Touch switches contain mechanisms, such as temperature, resistance, and capacitance. Correspondingly, a user or touch switch-specific object operating those features achieves high performance. However, specific functionality approaches rely on different touch switches technologies.  

4. Types of Touch Switch

Three types of touch switches exist on the market.

Capacitance switch

Human body capacitance provides a switch with functionality through a small electrical charge sourced from human or object interactions. Because of this, a capacitive switch continually charges and discharges, enabling it to act like a sensor that measures capacitance changes. In addition, human touches cause the capacitance to boost. 

As a result, distributing the electrical charge in the switch’s wiring occurs when the capacitance changes. Then, it determines where, when, and how physical interaction took place. In turn, this provokes certain functions, allowing the switch to operate. A capacitance switch requires just one electrode. Installation occurs behind a wood, glass, or plastic panel.

Capacitance switches provide durability, robustness, and reliability, making them long-lasting.

You can find these on circuits. Some applications also include proximity sensors, smartphones, vending machines, and home appliances. Additionally, these integrate into LED lights and IP ratings. For this reason, capacitance switches increased in popularity for environmental purposes.

Home appliances like these also utilize a capacitance switch

(Home appliances like these also utilize a capacitance switch.)

Resistance touch switch

Similar to a capacitive touch switch, the resistance touch switches functions based on electric current changes. These differ because of the simplistic design and build. Lower resistance between two conductive metal plates with a tiny gap helps the resistance touch switches to operate. Likewise, fingers come in contact with the plates when pressing the button. From there, conductive sweat directs electrical flow in that space, causing the circuit to close. As a result, the resistance switch activates, enabling the entire operation.

Because of limited functionalities, this type of touch switches isn’t applicable for smartphones. However, these offer stability, robustness, and longevity in many settings.

Printers contain a resistive switch

(Printers contain a resistive switch.)

Piezo touch switch

Lastly, piezo ceramic touch switches involve a piezoelectric effect. These consist of an internal ceramic layer that lowers when applying pressure to the external metal layer. Ultimately, this leads to the inner layer turning in a contorted form. Then, a generated electrical pulsation causes a semiconductor to make the switch work while pressed. Therefore, that means it can mechanically bend.

Thanks to the inner layer, this switch provides high durability and flexibility. Some contain a robust metal exterior casing for heavier applications. In that case, these require more applied pressure to work in such circumstances. Additionally, the easy-to-seal features make them accessible for the outdoors.

An application for the piezo switch

(An application for the piezo switch.)

5. How Do You Make a Touch Switch?

You will need the following components to build a touch switches:

  • 9V battery 1x
  • Battery clipper 1x
  • 3V LED 1x
  • Resistor 470 ohm 1x
  • BC547 NPN Transistor 2x

These steps will help guide you through the process:

1:  Solder the 470-ohm resistor to the transistor’s collector pin. Then, solder the LED’s negative wire to the 470-ohm resistor.

2: Next, solder the battery clipper’s positive wire to the LED’s positive end.

3: Connect the battery clipper’s negative wire to the transistor’s emitter pin.

4: Lastly, connect the 9V battery to the clipper to complete the circuit. You will need to perform a test, which ensures functionality. Touch both the transistor’s base wire and 470-ohm resistor wire simultaneously. Once touched, the LED should illuminate. The light turns off when you stop feeling the wires.   

Conclusion

In the long run, touch switches present several characteristics. With its capability, you can feel confident with more control. The different types also define how they should integrate into popular devices, such as a smartphone. For the most part, the circuit closes when you lightly press onto the touch switches, triggering a specific function. Comparatively, a mechanical switch requires more applied pressure. Therefore, that difference makes a touch switch the most common on the market today.    

Feel free to contact us if you have any questions regarding a touch switch!

Hommer Zhao
Hi, I am Hommer, the founder of WellPCB. So far, we have more than 4,000 customers worldwide. If you have any questions, you can feel free to contact me. I really appreciate any help you can provide.

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