Table of Contents
Advertisement
8.8 OUTPUT ROUTING AND POWER AMPLIFIERS
Analog
switches U402 and U403 are used to route the
and possibly range extended, signal to the left and right
amplifiers.
The
left/right switch and controls the analog switches accordingly.
The
use of
two power amplifiers (U400, U401) as
ability to
turn
cross-channel
approximately 1 watt, can be turned off for minimal current draw.
This is a very important feature for use under battery power.
series
130 ohm resistor at their output serves as an
for both signal and noise when the 60 ohm phones are connected.
8.9 POWER SUPPLY
The on-board power supplies consist of a +5 Volt regulator, -5
Volt regulator and a voltage converter.
whether it be from a battery or a battery eliminator, is
approximately +7 Vdc.
U102, +5 Volt regulator.
analog and digital circuits.
applied to converter U101 where, through its switched capacitor
is inverted to -7 Volts.
circuitry,
voltage is then applied to the -5 Volt regulator U100.
the voltage converter is disabled (shutdown) whenever the sleep
mode is entered.
through U202.
8.10 OSCILLATOR
The
oscillator is
functions:
U203 - level shifter
U202 - antialiasing filter
U201 - programmable switched capacitor filter
U200 - Low Pass/Band Pass selector
U203
takes
the 0 to 5 Volt sqaure wave (from
front panel selected frequency and converts it to a +5 V
This
signal is
antialiasing
filter
eliminate high freqeuncy harmonics.
applied to
the input of switched capacitor
switched capacitor filter is programmed via clock frequencies and
the
state of the 50/100 line.
found at the end of the I/O port designation listing (see
The switched capacitor filter is set to a Low Pass
for
all frequencies except 8 KHz where it is set for Band
This filter reduces harmonics and any other noises resulting in
a clean sine wave product.
CPU reads
the
them off (Pin 1) minimized
leakage.
The
This positive voltage is applied to the
The positive 5 Volts supplies both the
The unregulated +7 Volts is also
This is accomplished via controls switched
comprised of the following
then applied to the
"rounds"
status of
the
amplifiers,
which
The input supply,
The unregulated negative
antialiasing
the
the edges of
The
output of this filter is
filter
U201 (from U 5 0 7 controls can be
attenuated,
power
the
front
panel
well as
the
potential of
can
deliver
attenuator
Note that
IC's
and
their
U511.10)
at
the
signal.
filter.
An
sine
wave to
U201.
The
U507).
configuration
Pass.
A
Hide quick links:
Advertisement
Table of Contents
Troubleshooting
