274

Audio ICs

BA3430S / BA3430F / BA3430FS

(2)

Equalizer amplifier and metal switch circuits

The signal input from the magnetic head will be amplified

based on the NAB characteristics for normal tape or met-

al tape. The equalizer characteristics are switched be-

tween normal and metal according to the logic of the met-

al switch pin. A 22k

Ω or less resistor must be connected

to the input pin to limit the input current. The capacitor be-

tween the input pin and ground is for preventing switch

noise. It can be omitted without causing incorrect song

detection.

Input switch truth table

Equivalent circuit schematic

(3)

Mute circuit

This circuit mutes the output of the equalizer amplifier. A

22k

Ω or less resistor must be connected to the input pin

to limit the input current. The electrolytic capacitor be-

tween the input pin and ground is for preventing switch

noise. It can be omitted without causing incorrect song

detection, however, it is best to use it to ensure proper op-

eration of the mute circuit.

Input switch truth table

Equivalent circuit schematic