Line controlled two-color music light controller

The circuit of the wire -controlled two-color music lantern controller is shown in Figure 1-44
.
    The a and b terminals are pressed at both ends of the speaker. The audio signal taken from the speaker is added to both ends of the color-changing light-emitting diode LED
through the sensitivity adjustment potentiometer RP and the current limiting
resistor R , so that it flashes with the rhythm of the music. The LED and the photoresistor RG form a simple optocoupler, so the resistance of the RG changes as the LED turns on and off. When the music sound is weak or intermittent, RG shows high resistance, and the triac vs no trigger voltage is in the blocking state. Since the wattage of the lantern group Hl is much larger than the wattage of H2 in the setting , most of the 220V AC voltage Landing on both ends of H2, H2 emits a green light that is close to normal, while Hl only emits a weak red light; when the music sounds, the LED lights up. RG shows low resistance, vs gets the AC trigger signal and turns on, so H2 is short-circuited by vs and does not emit light, while Hl emits normal red light. Therefore, as the rhythm of the music rises and falls, the two sets of colored lights Hl and H2 alternately emit red and green light.