In the proposed device uses a so-called pulse-phase method of controlling the average current through the load. It changes due to the fact that the load is a lamp connects to the network, not directly, but electronic key some time after the appearance of the next half-wave of the mains voltage. Changing the time consumed by the load from the mains power can be adjusted from almost zero to maximum. For bulb lamp it means changing the brightness of its glow.
On closure of switch S1, the lamp L1 is switched immediately, but smoothly depending on the capacity of the capacitor C2. This increases the service life of the lamp, because we know that bulbs usually burn out when you turn sharp the connection voltage.
L1 (220V 100W) is actually a lamp. All resistors are 0.25 W, except for the R8, which is 2W. During installation, place this resistor in 2mm above the surface of the Board so as not to heat up other parts. The capacitor C1 of the LM SCR COL can be replaced by COOK, CUM, CUN. Observe the conditions of inclusion in the scheme. Connect incorrectly - will not work.
In the case in which You place the unit, be sure to drill holes for ventilation, because the elements R8, VS1 in the process heat up.
Publication: www.rp.butovonet.ru, www.cxem.net