By simply touching this touch dimmer switch you can increase the light intensity of incandescent lamps in three steps. Initially, when mains switch is on, the bulb is off. Now, if you touch the touch plate, the bulb glows dimly. On second touch, the bulb gives medium light. At the third touch, the bulb is driven fully. Another touch puts off the light.
The touch dimmer is built around 8-pin CMOS IC TT8486A/TT6061A specifically manufactured for touch dimmer switches applications. Since the IC is highly sensitive, use a long wire to connect the IC to the touch sensor. The circuit uses minimum external components. For touch plate, you can use a simple copper plate of 1cm×1cm or even the end of the lead wire. Touch plate is coupled to the touch detector through 820pF, 2kV capacitors C1, C2, and C3 connected in series.
Capacitors C1, C2, and C3 connected between touch input pin 4 and touch plate remove the shock potential from the touch plate, so do not replace these capacitors with a single capacitor or with a capacitor of a lower voltage rating. Mains potential exists in the circuit. Needless to say, it is dangerous to touch the dimmer switch circuit when mains is on.
Caution: touch dimmers are potentially dangerous if any electrical part is touched, so be very carefully at the circuit instructions.