Global Specialties 4005 - Manual - Manual (Page 18)

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3-5. TTL/CMOS OUTPUT
TTL/CMOS output is specifically designed for compatibility with TTL/CMOS digital logic circuits. Set-
up time is considerably reduced because the fixed logic levels and polarity are ready for direct
injection into TTL/CMOS circuits. There is a need for protection from the accidental application of too
high an amplitude or incorrect DC offset which might damage semiconductors. Another advantage is
the extremely fast rise time and fall time of signal. To use the TTL/CMOS output, connect a cable
from TTL/CMOS BNC on the Front panel to the point at which it is desired to inject the signal.
TL/CMOS output may be used in several modes of operation. See examples to follow.
A. Using the square wave generator or pulse generator modes, clock pulses can be generated for
testing, troubleshooting or circuit analysis. The instrument could even be used as a substitute
master clock generator as TTL/CMOS circuits can be driven from the TTL/CMOS BNC.
B. The CMOS Level Control potentiometer (out position) provides CMOS level output from 5V to
15V Variable and Continuously. To adjust the TTL/CMOS output level, rotate the potentiometer
switch and observe the TTL or CMOS output. Push the potentiometer in for TTL or out for CMOS.
3-6. Use as FM Signal Generator
1) Procedure
A. Set up equipment as described for function generator operation. Use the frequency and
amplitude controls to set the carrier to the desired frequency and amplitude.
B. Connect an AC modulating signal with no DC component to the VCF IN BNC on the front panel
of the generator.
C. Adjust amplitude of the AC modulating signal for the desired frequency deviation.
2) Considerations
A. The approximate frequency deviation for a given VCF IN signal can be determined as follows:
The 0.1 V change at the VCF IN BNC produces a frequency change of 1% of the highest
frequency obtainable on a given range. For example, the highest frequency obtainable on the 500
K range is 500 KHz. One percent of 500 KHz equals 5KHz, therefore a 0.1 V change at the VCF
IN BNC will deviate the output frequency 5KHz on the 500K range. The following table
summarizes the frequency deviation versus VCF IN voltage for all ranges.