Triac two-tone dimmer (1)

In the figure, Hl and H2 are red and green light bulbs respectively.
A potentiometer RP is used to simultaneously adjust
the conduction angles of the thyristors vsl and VS2. RP, Rl, R2 and CI form
the voltage regulating and phase-shifting network of the thyristor VS1, and RP, R1,
R3 and C2 form the voltage regulating and phase-shifting network of the thyristor VS2. After the power supply is turned on , the power supply
charges the capacitors Cl and C2 through Rl and RP (assuming the RP sliding end is at the center) and resistors R2 and R3 respectively. Changing the time constants of (RI+RP+R2)xCl and (R1+RP+R3)
x C2 can change the conduction angles of the thyristors
vsi and VS2, thereby changing the brightness of the lamps Hl and H2. It can be clearly seen from the figure that when the sliding end of RP moves to the left, the light H1 gradually lights up and the light H2 gradually dims; conversely
, when the sliding end moves to the right, the light H1 gradually dims and H2 lights up again.