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Text File
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1979-12-31
|
2KB
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60 lines
RS232 TO MIDI INTERFACE 23-Jan-89
-----------------------
RS232 TX ,-------------R2------- 5
| / MIDI OUT
2 ----R1---,----|: Q1 ,----R3------- 4
|+ | \ |
D1 |e |
| | |
gnd gnd |
|
|
|
+12v ------, | <-- test point +5 volts
| + |
|-----D3-----,-------'----------,--------,-----,
| | | | |+
RS232 RX R4 | | R8 === C1
| R5 | | |
3 ------'--, | 5 gnd gnd
\ | | ,---'----,
Q2 :|------'-, | |-1---,---R7--- 4
/ | \ | | | |+
e| Q3 :|----,--4-| U1 | D2 MIDI IN
| / | | | | |
RS232 GND | e| R6 | |-2---'-------- 5
| | | '--------'
7 ---------'-----------'-------|
|
gnd
Components:
Q1, Q2, Q3 BC548 transistor
U1 MCT2E opto-isolator (see below)
D1, D2 1N4148 diode
D3 6v8 1w zener diode
C1 10uf 16v capacitor
R1 6k8 resistor
R2, R3, R7 220r "
R4 3k3 "
R5 2k2 "
R6, R8 1k "
Notes:
a) Diode cathodes are marked as '+' while transistor emitters
are marked as 'e' .
b) Alternative opto-couplers are 4N25, 4N26, TIL116. If R6 is
changed to 2k2 then 4N27, 4N28, H11A4 may be used.
c) Some computers may require RS232 pins 2 and 3 be reversed.
d) MIDI IN/OUT sockets are 5 pin 180 degree DIN audio sockets.
e) For operation using +5v instead of +12v, remove R8 and
replace zener diode D3 with a shorting link.
f) Bondwell 14 only. +12v is available on pin 25 of the RS232
connector.