With a wave of the hand, turn on a USB powered touch-switch LED Lamp. You do not have to actually touch the sensor. It is so sensitive, it will activate by the presence of a finger an inch or two away. While the circuit described here is shown activating an LED Lamp, with the addition of a relay, it can be used to activate almost any electronic device when you turn on your PC.
This instructable also details how to make functional curved circuit boards that can serve as a case and a circuit.
It also shows a fast, easy and inexpensive way to etch patterns and solder able traces on any simple circuit board.
The video shows how the lamp is turned on and off.
The intro Pic shows the touch switch lamp on the left and some other etched curved circuit boards that await components.
Step 1: How It Works
The touch switch circuit is based on the QT-113 integrated circuit. It works by detecting changes in capacitance. When it is first turned on it measures capacitance at its sensor plate. When a human touches or comes near to the metal sensor plate the capacitance is changed and the circuit turns on.
The sensitivity is adjustable so that at a lower setting it will require you to directly touch the sensor plate. At its most sensitive setting, it will detect your finger through paper, plastic, glass, or even a brick.
The larger the sensor plate the more sensitive the switch. The sensor plate is the triangular circuit board at the front bottom of the lamp.