TTP223 DIY Touch Upgrade: Wireless Keyboards Enhanced

In the ongoing enhancement of one of the two previously crafted UbiConnect wireless mechanical keyboards, an issue with backlight control via a toggle switch has been addressed.

Introducing the TTP223 touch module—an adaptable component operational within the power range of 2.5v to 5.5v. This module offers touch and self-locking functionalities, providing output signals for both high and low voltage levels. It can seamlessly interface with microcontrollers, transistors, or other device switches to incorporate touch-sensitive capabilities.

Given that the original main control of the DIY keyboard is obsolete, necessitating the independent control of backlighting, the implementation of a self-locking switch became imperative. Notably, the touch switch itself accommodates a current of approximately 10 to 20 mA. To address this, a 2N5551 transistor, or a suitable alternative like the 8050, was introduced with a 4.7k resistor in tandem. This configuration ensures an optimal current flow of around 45 mA, resulting in the desired brightness for the keyboard.

The diminutive size of the module, roughly equivalent to that of a keycap, facilitated seamless integration onto the main control board using 3M double-sided tape. A meticulous soldering process involving three wires was employed, initially employing standard wires for the touch-sensitive segment. However, recognizing the potential for false triggers due to improper wire installation, a spring from a red switch was strategically soldered to the touch point. The outer shell of the keyboard saw the addition of a 1-square-centimeter aluminum foil, affixed with adhesive backing. This configuration, upon installation, allows the spring to exert pressure on the foil, creating a defined sensing area.

The user experience is further enriched as a gentle touch on the keyboard's logo activates the backlight, delivering an impressive visual effect. Notably, the light can be triggered without direct physical contact with the keyboard, requiring only a subtle hover approximately 1 centimeter above, mitigating the risk of unintended activations.

For those with surplus touch switches, the versatility extends to various applications.

Example 1: Enhance small portable devices with a battery indicator light switch, particularly beneficial when the aesthetics or practicality of installing a physical switch are constraints.

Example 2: Elevate the control of 220V household appliances by integrating a transistor and resistor behind a touch switch, subsequently linked to a relay for efficient management.

Example 3: Simplify household appliance controls originally reliant on microswitches by seamlessly substituting them with touch switches, eliminating the need for additional electronic components.

This comprehensive integration of touch-sensitive technology not only ensures the seamless functionality of the DIY keyboard but also extends the potential applications for touch modules in diverse electronic setups.