touch dimmer

The novel feature of this lamp dimmer is that the circuit is totally solid-state and uses no mechanical switches nor potentiometers. The lamp can be switched on and off and faded up and down simply by placing a finger on a touch plate. The heart of the circuit is a Siemens SS 66B IC. This IC is basically a triac phase-controller, i.e. the lamp brightness is controlled by varying the point in the mains cycle at which the triac triggers, as shown in figure 1. The sooner the triac is triggered the greater the conduction angle of the triac and the more power is delivered to the lamp.