Description
The HA12134A, HA12135A, HA12136A are silicon monolithic bipolar IC series providing dual channel Dolby B-type noise reduction system* in one chip. The circuit is used primarily to reduce the level of background noise introduced during recording and playback of audio signals on magnetic tape.
HA12134A series provide the following functions and features.

Features
•  Separate record/playback input and output.
    Unprocessed signal output available in the encode and decode modes.
•  Reduction of external components count.
•  Small capacitor value for the reference voltage.
•  NR ON/OFF switching and REC/PB switching are provided internally.
•  2-type package (DP-16, FP-16DA)
•  Wide range of operating supply voltage.

Functions
•  Dual Dolby B-type NR processor
•  NR ON/OFF control switch.
•  Record (encode)/playback (decode) control switch.