[How to] From Mechanical to Capacitive controls (Button with sharp edges and 2mm clearance, 2 layer pcb with cover glass (50x70mm))

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Everything you need to know to get started on Capacitive Controls

 

Even though most of you may be relatively familiar with the various types of mechanical controls, the same does not necessarily apply for capacitive ones. So, let’s start off by defining the most basic elements of capacitive sensing.

 

Capacitive buttons are the simplest touch - enabled controls out there. Buttons simply alternate between ON/OFF states when touched.

 

Capacitive sliders consist of groups of buttons, usually more than three. Sliders use buttons to report linear touch position.

 

Capacitive wheels are also groups of more than three buttons. Wheels use buttons to report angular touch position. Wheels can also be referred to as rotaries.

 

Capacitive controls can detect touches even if they housed under materials that cover them. Do you want an all-aluminum body for your device? No problem, you can just use capacitive controls and house them underneath it!

In fact, with proper design and capacitive touch sensor controller tuning, capacitive controls can work under a wide variety of cover materials (also called overlays) of various thicknesses.

 

But it’s not just the freedom regarding overlays that you can gain from using capacitive controls. You can also experiment with curved or bent designs, as capacitive sensing has evolved enough to be able to withstand bending!

In this use case, we will optimize a touch remote light switch. Traditionally, such a device would feature mechanical components. However, we'll show you how easy it is to design a capacitive- based device, if you have the proper tools.

To refine the design, we’ll use a combination of simulation and guidelines.

 

Real-life use case: Optimizing a touch remote light-switch through simulation

We proceed to draw the initial design of the model, which you can see above. This rough design has the following specs:
 

  • Button with sharp edges and 2mm clearance
  • 2 layer pcb with cover glass (50x70mm)
  • No traces, as we’ll add them later
     

 Get our guide here and start designing now.