In principle - this design is a graphic illustration of the theme: laziness - the progress engine. Tired of trekking to the store to buy light bulbs.
When using this device, the lamp life is increased considerably, some specimens are up to 4 years. This effect is the gradual heating of the filament, as is known, the combustion of the lamp occurs at the moment of inclusion. Moreover, when included in the dark there is a convenience in terms of a smooth change of light as your eyes time to adapt and there comes a dazzling effect.
R5 determines the level of initial filament bulbs. R7 determines the slew rate of the filament, within 3-5 seconds, lower value does not prevent the lamp from burning. R1 provides the necessary voltage (requires selection at the twinkling lights in fault in the network).
It is recommended to install in a broken wire near the switch, or if that spoils the aesthetics of the room, directly at the light (perhaps in it).
Publication: www.cxem.net