Making you own AMIGA-Midi interface (500, 500+ and 2000 only!).

Introduction
Of course we print a schematic for our commodore friends! The commodore AMIGA
has probably the  easyest connection  to Midi. So the midi interface is quite
cheap to build. The presented interface here has IN, OUT and THRU capability.

Schematic
Join me for a walk trough the schematic.

At the top we see...
-J1.	Incoming signal
-R1.	Current limiting resistor
-D1.	Reverse voltage protection (static discharge)
-ISO1.	Optocoupler
-R2.	Pull up resistor
-J2.	THRU output. The incoming signal is echoed into this plug.
-R3, R4	Current limit resistors
-U3A,B	Buffer the incoming signal to send it to the THRU plug

In the middle...
-J3.	OUT plug
-R5,R6	Current limit resistors
-U3C,D	Buffers to amplify the signal from U4
-U2	5 Volt power supply. The AMIGA only supplies +/-12 Volts
-C1, C2	Decoupling capacitors for U2. Should be placed very close to U2!!
-U1A	RS232 transmitter. Has 3 power connections! (VPP, GND and VMM)
-U4A	RS232 receiver. Has 2 power connections (VCC and GND)

Down below you can see...
-P1	Connector to AMIGA's serial port

Power distribution
Of course the several chips in the circuit need power. There are 4 power
'labels' namely:
-VCC (+5V)
-VPP (+12V)
-VMM (-12V)
-GND (0V)

All VCCs should be connected together, all GNDs should be
connected together, etc...

PCB
This circuit can most certainly be build on a piece of pre-printed (and pre
drilled) PCB. The profs amongst us can design a PCB is they like.

Housing
This circuit probably won't fit into a standard sub-d housing (maybe it will
when SMDs are used). To keep the housing small you can connect the DIN plugs
to the circuit by a piece  of cable instead  of mounting the  plugs onto the
housing.

For compliments, suggestions,  remarks or even criticism  feel free to email
me at the following adress.

nctnico@cistron.nl