Lectrosonics LE Series - Manual (Page 3)

GENERAL TECHNICAL DESCRIPTION
The LE8 is comprised of five major functional subsystems: the balanced input, the programmable four band
equalizer, three programmable notch filters, the balanced and floating output driver, and the microprocessor (see
block diagram below).
The input circuit of the LE8 is a fully balanced, RF filtered differential amplifier. The balanced circuit topology
provides high rejection of common mode signals. It may also be configured to accept unbalanced signals.
The balanced and floating output driver is fully RF filtered, and provides the benefits of transformer coupling without
the low frequency distortion and core saturation that plagues transformers. High current operational amplifiers are
used in the output driver, allowing long cable runs to be driven easily. The output driver may also be easily
configured for unbalanced use.
The microprocessor, a Motorola MC68HC705C8, provides all control and interface functions for the LE8. The
MC68HC705C8 has internal non-volatile memory which stores the control program for the LE8 (note that filter setup
values are stored in a separate off-chip non-volatile memory with data retention that exceeds 100 years). The
microprocessor also provides both parallel and serial ports for interfacing with filters, controls, and indicators. The
high integration density of the microprocessor allows for a much lower parts count design, thus increasing reliability.
All filters are programmed by the microprocessor as appropriate for the particular active microphone. In addition, all
user controls are scanned by the microprocessor to provide the user interface. Link In and Link Out functions are
provided so that more than one LE8 may be used in an installation.
3 NOTCH FILTERS
PROGRAMMABLE
50-5KHz
8 LINES
SERIAL/PARALLEL
CONVERTER
TONE CONTROL
PROGRAMMABLE
4 BAND
MICROPROCESSOR
SERIAL DATA OUT (SDO)
SERIAL CLOCK (SC)
NOTCH FILTER DATA LATCH
OPERATE
NEW SETTING
NOTCH
#1
NOTCH
#2
#3
NOTCH
TREBLE
MID TREBLE
MID BASS
BASS
LOGIC IN #1
LOGIC IN #2
LOGIC IN #3
LOGIC IN #4
LOGIC IN #5
LOGIC IN #6
LOGIC IN #7
LOGIC IN #8
ACTIVE
BYPASS
STORE SETTING
TONE CONTROL
DATA LATCH
NOTCH/EQ DISPLAY LATCH
ACTIVE LOGIC IN DISPLAY LATCH
FUNCTION LED DISPLAY LATCH
NOTCH
FREQUENCY
EQ LEVEL
DISPLAY
DISPLAY
INPUT
LOGIC
ACTIVE
DISPLAY
LED
FUNCTION
EEPROM
MEMORY MEMORY
LATCH
LINK IN
LINK OUT
ROTARY ENCODER
ADJUST
LOGIC INPUTS
LINK IN/OUT
USER CONTROLS
USER DISPLAY
MICROPROCESSOR AND NON-VOLATILE MEMORY
NOTCH FILTERS AND TONE CONTROLS
INPUT AMPLIFIER
OUTPUT AMPLIFIER
Figure 1 - LE8 Block Diagram
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