Making a 3-way Switch Button From a Refurbished Computer Mouse.

Since the advent of the wireless computer mouse, many old mice have cluttered our drawers or, at best, ended up in a special bin for recycling electronic products.

However, these mice hold substantial value for electronics engineers due to their component makeup :

• Basic NPN transistor
• Actually a 16x16 pixels camera
• Resistor
• Capacitor
• IR LED and IR detectors
• Press buttons.

The dual-lane feature of these switches is noteworthy. The main pin located close to the button is connected to the end terminal when idle [B1]. When pushed, it connects to the nearest pin [B2]. This design streamlines the assembly process by eliminating the need for resistors in pull-up or push-up assembly.

The switch button is tiny, making it hard to operate. To make it more user-friendly, we created a 3D-printed housing.

 The housing is the first element, with a cavity corresponding to the size of the switch: L= 13 mm; l = 6mm, h = 6mm. The thickness of the walls is 1 mm. The cover is partially finished and consists of a flexible strip of 0.5 mm thick.

The second part is the button head. Its dimensions are tailored to fit the fixation tab's width (4x4 mm) and to the size of a normal finger (surface area of about 12 mm²).

Final assembly is accomplished by gluing the various parts together with a cyanoacrylate adhesive.

Further Reading : « 100 Sensors In Action, Electronic For Chemists » - Gérard Bacquet- SciencExpert Edition - 2024