Double cassette tape recorder system preamplifier

The BA3423S is a record /playback system preamplifier for radio cassette decks. With four control pins it allows switch ing between I/O for the A (play only) and B (record and play) mechanisms, input for tape, radio, and microphone, on and off switching for line out and recording output, and equalizer switching for normal and high-speed dubbing. It requires about half the number of external components of its predecessors which means simplified assembly and over all cost savings.

Features
1) Built-in switch for playback equalizer amplifier for the A and B mechanisms.
2) Built-in normal /high-speed equalizer switch for the playback equalizer amplifier.
3) The B mechanism input is also used as the recording output, so a switch is not required.
4) Built-in tape /radio input switch, and microphone mixing.
5) The microphone amplifier is used as the mixing amplifier, and the line can be muted to allow the built-in
microphone to be used for recording.
6) Built-in ALC circuit.
7) Built-in recording equalizer circuit, and internal switching of the normal /high-speed equalizer is possible.
8) All stages are directly connected, so coupling capacitors are not required.
9) Muting is applied as required during switching to reduce switching noise (transition muting).
10) Pin assignments has been designed to facilitate placement of attached components and PCB design.

Applications
Dual-cassette radio cassette players.