Tait TB8100, Service Manual

Page: 272 / 306

272 Control Panel Circuit Description TB8100 Service Manual
© Tait Electronics Limited September 2006
17.1 Control Circuitry
Standard, Dual Base
Station, and Power
Save
The control panel translates I
2
C messages into an appropriate response on
the LEDs. It also translates button inputs from the front panel membrane
and fan rotation inputs from both fans into appropriate I
2
C messages. The
type of control panel is also sent with I
2
C messages.
The control panel translates RS-232 from the programming port into 0V to
5V open-collector signals which are connected to the reciter (or to the
selected reciter in a dual base station).
Multi-reciter
The control panel translates I
2
C messages from the reciter into an
appropriate response on the LEDs (except the channel LEDs). It also
translates control panel button inputs (except the channel button) and fan
rotation inputs from the PMU fan (if fitted) into appropriate I
2
C messages.
The type of control panel is also sent with I
2
C messages.
The control panel translates RS-232 communications from the
programming port into 0V to 5V open-collector signals which are
connected to whichever reciter is selected with the channel button.
17.2 Audio Circuitry
Standard and Dual
Base Station
The volume of the speaker is controlled by the volume control knob. In
addition, the control panel performs gain control so that, with an input of
167mV pp, the power output into a 16
Ω
speaker is
≥
0.5W at the maximum
position of the knob, and 0W at the minimum position of the knob. An
LED indicates when the speaker is on.
The control panel is designed to work with an electret microphone with an
input range of 80dBSPL to 115dBSPL.
Power Save
The audio circuitry is not fitted to this board.
Multi-reciter
The multi-reciter control panel provides a volume knob to control the
volume of the speaker. In addition, the control panel circuitry performs a
summation of the audio signals from all reciters and provides a 0.5W drive
for the 16
Ω
speaker. Speaker audio is a shared output from any combination
of reciters in the subrack, depending on the speaker mute setting for each
reciter.
The control panel is designed to work with an electret microphone with an
input range of 80dBSPL to 115dBSPL.