Radio Shack VoxBox TRS-80 User Manual

Zero-Crossing
Detectors
The
zero-crossing
detectors
outputs
should
be
volts with no
input and
swing
to
5
volts
when
the filter
output
swings
much below
its rest level
of
6
volts.
Whistling into the
microphone
should
produce a square
wave output
whose period
varies with the pitch
(frequency)
of the whistle.
Table 3
summarizes
this
test.
TABLE 3
Signal
Input
(at
MIC.)
High Band
Low Band
Output
IC4-14
Input
IC4-8
Input
IC4-9
Output
IC4-13
Input
IC4-10
Input
IC4-11
Whistle
Square Waves
to +5V
at
whistle
frequency
Sine Waves
Swinging
Above & Below
+6V
DC Voltage
Slightly Less
Than 6 Volt
Reference
at
IC5-5
Square
Waves
to
+5V
Sine
Waves
Swinging
Above &
Below
6V
DC Voltage
Slightly Less
Than 6 Volt
Reference at
IC6-12
None Random
Square Waves
6 VDC Same as
above
Random
Square
Waves
6 VDC
Same
as
above
Rectifier/
Averagers
The
comparator
outputs
should sit at volts
with no signal and go to
+5
volts with signal into
the
system.
The amplifier
outputs should sit at 6
volts with no
signal input and sit at a
steady
state voltage
less
than 6 volts for steady state
sounds
( Ahhh
etc.).
Table
4
sum-
marizes the
results.
Low Band
Amplifier 1C5-8
High Band
Amplifier IC5-14
Low
Band
Comparator
1C4-1
High Band
Comparator 1C4-2
TABLE 4
Signal Input
to 5 volts
to 5
volts
5
volts
5
volts
No
Signal Input
6
volts
6
volts
volts
volts
-8-

Radio Shack VoxBox TRS-80 Specifications

General

Brand	Radio Shack
Model	VoxBox TRS-80
Category	Control Unit
Language	English