You may have used a floor or desk touch lamp before and have wondered how it worked. For such an easy way of activating the lamp, the internal mechanisms can actually be quite complicated.
The outside surface of a touch lamp is usually metal which acts as a conductor, or an antenna. The special circuitry that can be found in a touch lamp is constantly providing positive and negative charges to the surface of the lamp. As long as there is no interference with the circuitry, the charges will remain neutral or negative; however, when someone touches the lamp, it sends a charge to the lamp that is measured by the circuitry.
Binary Flip Flop
Rather than a switch or dial that regular lamps have to signal the lamp on or off, touch lamps have an internal circuitry that remembers whether the lamp should be on or off. When the signal is sent to turn the lamp on, it "switches" the bulb on, and vice versa.
Alternating Current (A/C)
The primary function required of a touch lamp is the ability to store a current, which is called capacitance. When the lamp is touched the A/C current is activated, signalling the lamp to switch on the light bulb. Some touch lamps even have three levels of brightness that can be controlled by touch.
Modern floor touch lamps contain a silicon chip that contains all of the circuitry necessary to operate the lamp. Touch lamps either come installed with this chip or you can turn a regular lamp into a touch lamp.