5G169 holiday lights integrated circuit

The AC power is rectified by VDI~VD4 bridge to output full-wave pulsating DC power
  for four-way lanterns . Rl, R2, VD5 and VD6 form a simple voltage stabilizing
  circuit. After filtering by Cl, it outputs about 6V DC power for the integrated block. VD6
  plays an isolation role here, so that both ends of R2 can obtain a 6V full-wave pulsating
  DC voltage. The pulsating frequency is 2 times that of the alternating current, that is, 100Hz. This 100Hz
  signal is injected into pin 8 of the integrated block through R4 as a synchronization signal. In the figure, SB is
the forward and reverse control switch. SB is open for forward circulation; SB is closed for reverse
  circulation. Figure 2-102 shows the waveform circle output by pins 9 to 12 during forward cycle.
The dotted arc line represents the change of light brightness. The adjustable range of period r is 100ms to 5s.