Consideration about the touch switch on the base

A project log for Interactive VU LED tower

A tower high 90cm made out of acrylic that lights up with the music or sensing the position of a hand on top of it.

EstEst 05/27/2016 at 08:340 Comments

At the base of the tower there is a touch button used to turn on and off. The touch sensor IC is mounted on the PCB at the center of the base with a switching voltage regulator and a driver for the four power leds mounted on the base. The sensing plate of the touch sensor is a coin glued on the internal side in one corner of the base. To connect the board with the sensing plate i used a simple wire, but i found that the wire was sensitive too. I tried to use a coaxial cable for microphones with the shield connected to ground but in this way the button was not responsive anymore, i think due to the capacitance of the coaxial cable itself. The solution was to made by myself a coaxial cable where the cenral wire and the shield are more separated to reduce the cable capacitance but keep the shielding effect.