to an internal 12VDC power supply, with a 680 ohm current limiting resistor in series. The output transistor
of the optocouplers have 10K pull-up resistors on their collectors, with the emitters connected to ground and
are buffered by an inverting gate. The following diagram is representative of the Contact #25 input and is
similar for Contact #26:
Contact #25
GROUND
+12v
+5v
680
ohm
10K
ohm
The input is activated by sinking current from the Contact input pin to ground. A Ground connection is
supplied on pin 10 of the
Main
connector for this purpose. The input current sink requirement is
approximately 10mA. The contacts are associated with sound files named 19x.WAV and 1Ax.WAV. The x
denotes additional file control attribute characters. See the
Filename Formats
section below.
Speaker Connection
The speaker terminals on the
Main
connector provide connections for the two external left and right
speakers. These may be either 4 or 8 ohm speakers, with 4 ohms providing higher output power. The speakers
should be capable of handling up to 25 watts.
NOTE: THE SPEAKER OUTPUTS ARE NOT REFERENCED TO GROUND –
EACH SPEAKER REQUIRES ITS OWN PAIR OF WIRES, AND NEITHER WIRE
MAY BE CONNECTED TO GROUND.
G
R
O
U
N
D
1
0
V
-
1
8
V
D
C
P
T
T
C
o
n
ta
c
t N
.O
.
P
T
T
C
o
n
ta
c
t C
O
M
In
p
u
t C
o
n
ta
c
t 2
6
In
p
u
t C
o
n
ta
c
t 2
5
R
ig
h
t S
p
e
a
k
e
r +
L
e
ft
S
p
e
a
k
e
r -
L
e
ft
S
p
e
a
k
e
r +
R
ig
h
t S
p
e
a
k
e
r -
1
2
3
4
5
6
7
8
9
10
Pin #
Signal
Filename
1
Left S
2
Left Speaker -
3
Right S
4
Right Speaker -
5
Input Contact 25
19C.WAV / 19O.WAV
6
Input Contact 26
1AC.WAV / 1AO.WAV
7
PTT Contact COM
8
PTT Contact N.O.
9
10VDC – 18VDC
10
Ground
