 
                         396 AUDIO AMPLIFIER
                         -------------------


                                   Ŀ
                                Ĵ O            Ŀ
Simple to use             +GAIN 1                8 GAIN
audio amplifier                 Ĵ              
with gain of 20.                                 
Operates from                   Ĵ    \        Ŀ
single polarity             -IN 2 Ĵ  \       7 BYPASS
supply. Connect                 Ĵ  -     \    
10f capacitor                               > 
between pins                    Ĵ        /   Ŀ
1 and 8 for                 +IN 3 Ĵ  /      6 +V
gain of 200.                    Ĵ  + /       
(not for this                                   
application)                    Ĵ             Ŀ
                            GND 4             Ĵ 5 OUT
                                Ĵ              
                                   



MAXIMUM RATINGS

Supply voltage        +15 V
Power dissipation      660 mW
Input voltage         0.4 V
Operating temp.       0C to 70C

CHARACTERISTICS

Supply voltage range       +4 to +12 volts
Standby current             4 to 8 mA
Output power                250 to 325 mw
Voltage gain                20 to 200
Bandwidth                   300 kHz
Total Harmonic distortion   0.2%
Input resistance            50 K

APPLICATION FOR AT&T PC6300 or PC6300 PLUS

                             +5volts (note 1)
                                  +                 *320f capacitor
        GAIN=20                 Ĵ(Ŀ             for CPU noise
                                  320f *           reduction
                           3\         
                   Ĵ+ \6      
                               \  5      220f
                            386  >Ĵ(Ŀ
          +        v            /          +           
   IN+ Ĵ(/\/\/\Ĵ- /4                    Ŀ/  8
 to term   1f   10k      2/                             speaker
 1 of          volume                               \
 PC6300        control                                 
 speaker       (note 2)                       +        
                        )
                                             1f   
                               gnd                 IN- to term 2
                            (note 1)                   of PC6300
                                                       speaker



Note 1. Power and ground is supplied from the floppy drive power
        connection. Purchase a floppy drive power "Y" connector.
        Cut off connector on one leg of the "Y" and insulate the
        yellow/black pair (+12/gnd). Use the red/black pair for
        +5/ground.

Note 2. The volume control can be located on the back of your computer
        instead of the breadboard if you think you may want to make a
        lot of adjustments. Remove one of the blank card end supports 
        from an unused slot and drill it out to receive an appropriate 
        10k volume control. Run three leads from the volume control to
        the speaker/amp breadboard.

Note 3. Most components can be purchased at Radio Shack or other
        electronics jobber. All parts cost me less than $15.

Mount all components to an approx. 3"x5" breadboard. Trim one end
of breadboard to fit into one of the short sockets of 16 bit buss.
This supports the board only - there are no connections to the socket.
Observe polarity of all capacitors. Also, I suggest you use a
IC socket and make all connections before plugging in the 386 audio
amplifier. After all components have been mounted on the board insure
that the power has been turned off and the power cord has been unplugged
from the computer. Remove top and bottom covers. Insert the speaker/amp
board into the 16 bit buss socket.  Remove the disk drive power
connector from the power supply and add your "Y" connector. Plug the
disk drive power connector into the "Y". Run the two wires for the
speaker connection thru one of the holes between the chassis and the
buss board/motherboard and connect to the speaker. Observe polarity
when attaching leads to speaker. Terminal 1 of the speaker should be
connected to the input of the 386 audio amplifier (thru the 1f 
capacitor, the 10k volume control to term 2 of the IC).
Replace bottom cover, set the computer rightside up and boot. Run
something that will generate some sound and adjust the volume. Replace
the cover and enjoy.

Yes, these instructions are very abbreviated. You should have 
some experience before you attempt this. Look the job over very 
carefully. Check the motherboard speaker connections, power 
connections, etc. before you start. You assume all risks for anything 
you construct and install. This modificaton may void any warranty you 
may still have on your computer. If you are not familiar with simple 
construction and soldering techniques get someone who is to help you. 
Good Luck.

Brad Pearson
Rohnert Park, CA
