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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