Doorbell Integrated Circuits - HK523

Dual tone sound effect , " Ding - Dong "
   and  " Bird " sound for 2 sounds available .
 2 alone sound output from 2 alone trigger
   pins touched .
 Trigger mode by one shot re-trigger type .
 Sound quality can modify from envelope's
   capacitor or Rosc ( oscillator resistor )
   value changing .