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14
5.4
VCF Operation
The
VCF (Voltage
Controlled
Frequency) mode permits the user to adjust the function generator
frequency with
an
extemal DC control voltage.
A. Push
the desired
FUNCTION button for square,
triangle,
or sine wave output.
B.
Push
the
desired Range button (lM, lOOk,
lOk,
lk, 100, 10, 1) for the desired
frequency.
C. Rotate the
FREQUENCY knob until the desired frequency appears in the Frequency
Display
window.
D.
Make certain the SWEEP WIDTH knob is pushed in, enabling the VCF mode.
E.
Connect the control voltage to the VCF/MOD IN connector.
NOTE:
The VCF input controls the output frequency over a range of 3 decades; the same
control range the FREQUENCY knob provides for a given frequency
multiplier
range (i.e.,
when
the XlOk frequency multiplier button is pressed, the range is 20Hz to
20kHz).
The VCF
input modifies the initial frequency setting-within the original 3 decade control range. With a
frequency setting of
20kHz,
applying
+
IOV to the VCF input will reduce the frequency,
by
approximately 1000:1, to 20Hz. An application of -IOV to a setting of 20Hz will increase
the
frequency to approximately 20kHz. If the setting is within the range limits, a VCF input will
change the output frequency up to the range Iimits. A positive voltage input causes a
decrease
in output frequency while a negative input causes an increase in output frequency
.
F.
Adjust the AMPL control for the desired voltage level on the Output connec tor, or pull the
TTL/CMOS knob and adjust the desired output level on the TTL/CMOS output connector.
G. If necessary, ad just the DUTY and OFFSET knobs to change the duty cycle orto adda DC
offset voltage to the
waveform.
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