Time-varying dimmer circuit - has two transistors controlling charge of starter capacitor

摘要

The intensity of illumination of large lamps controlled by a timer function ensures automatic and slow dimming after a preset working period. It also allows for slow rise in illumination intensity after switching on the lamp, the dimming and gradual increase of illumination facilitating the use of a staircase and its switches. The slow rise of lamp current extends service life of projector lamps, while the inclusion of complementary transistors and low-value storage capacitors simplifies time behaviour control. The charge current of starter capacitor (C1) is set by transistors (T1,T2) with the charge circuit comprising diodes (D1,D2) controlled by a switch(S). The bases of transistors are connected to storage capacitors (C2,C3) via resistors (R1,R2). The voltage limiter includes diodes and zeners.