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11
SUGGESTED LOGIC APPLICATIONS
This section contains suggestions on the uses of the SCM810's logic capa-
bilities. Note that uses of these functions are not limited to the listed appli-
cations. The user is limited only by individual imagination and creativity. For
additional suggestions and solutions to installation problems, contact
Shure's Applications Group.
In the following paragraphs, the wiring diagrams refer to the DB-25 connec-
tor pins shown in Figure 4.
Cough Button
The talker can turn off his or her microphone during coughing or private
conversations by installing an SPST pushbutton switch between the MUTE
IN and Logic Ground pins for each channel to be modified (see Figure 12-
Channels 1, 2 and 3 modified). When a channel is muted, no audio is
passed. (See “Dead Zone on MUTE IN Defeat” in Internal Modifications
section for more information on MUTE IN logic.)
COUGH BUTTONS
FIGURE 12
Chairperson-Controlled Muting
The chairperson can, by activating a switch, silence all other microphones
and be heard without interruption. For operation in this mode, connect all
the MUTE IN pins together except that of the chairperson's channel, and
wire an SPST pushbutton or toggle switch between those MUTE IN and
Logic Ground pins (see Figure 13-the chairperson is shown as Channel 1).
An alternative to a switch is to connect the chairperson's GATE OUT to the
MUTE IN of other channels. When the chairperson's microphone activates,
all other microphones mute.
CHAIRPERSON-CONTROLLED MUTING
FIGURE 13
Remote Channel-On Indicators
Remote indicators can be used to indicate when a talker's microphone is
on. Connect the LEDs and a 5-volt supply to the GATE OUT pins as shown
in Figure 14 (Channels 1, 2 and 3 shown modified). To avoid switching
clicks in the audio output, do not ground the power supply negative terminal
in the audio system or rack ground.
IMPORTANT: If a single cable is used for the microphone audio signal and
the LED dc power, separate shielded pairs must be used. Failure to carry
the dc power on a shielded pair may result in audible clicking due to capac-
itive coupling between the dc power lines and microphone lines.
REMOTE CHANNEL-ON INDICATORS
FIGURE 14
Disabling the Gating Function (Bypass)
To keep certain microphones on at all times, wire the desired microphone
channel's OVERRIDE IN pins together to the Logic Ground pin. The
selected channels now function as they would in a non-automatic mixer
(see Figure 15-Channels 1, 2 and 3 modified).
GATING BYPASS
FIGURE 15
M1 M3
M2
LOGIC
GROUND
CH. 1
M3 M5M5 M7
M2 M4 M6
LOGIC
GROUND
5 V POWER
SUPPLY
+
–
R = 470
&!
G1 G3
G2
LOGIC
GROUND
, 1/4 W
O2
O1 O3
LOGIC
GROUND