BWD MINI-LAB 603B Manual page 17

4.
OPERATION
(continued)
The symmetry change
of the
waveform
is
achieved by
increasing the time
duration
between alternate half cycles,
hence
the overall effect
is
to
decrease frequency
as
the
symmetry
ratio
changes
from
1:1
to
either 50:1
or 1:50.
The beginning of a
cycle
of the square
wave
switching
waveform coincides with
the
peaks
of
both
the
Sine
and
Triangle
waveforms. Since
the
symmetry
control
works on
ail
three
output
waveforms
the three
waveforms appear
as
below:-
Setting the controls as
shown below/ the frequency
of the generator
can be swept
over
any desired portion of the selected
frequency
range.
The sweep width
is
adjusted
by the
Ramp
Amplitude
control
and
the
starting
frequency by the Frequency
control.
To
vary the
sweep speed
adjust
the
Ramp
Frequency
control.
Should the
Frequency
Control
and
the
Ramp
Amplitude
control be
set
such
that
the
upper frequency
limit
would
lie
outside the calibrated range, an automatic
frequency
limiting circuit will
re-set the
ramp each
time
it
exceeds the calibrated
frequency
limit.
UL
-t
5(-
6.7-
F dial
_set..to.5_
10
UL
F
dial
set to
9
U
L
= Upper Frequency
Limit
4-4
603B