Global Specialties 4005 - Manual User Manual

Page 14

Figure 3 OUTPUT WAVEFORMS AND PHASE RELATIONSHIPS

I. A positive or negative DC component can be added to the signal at the 50 BNC by use of the

DC OFFSET control, as required by the circuit into which the signal is being injected.

J. A fixed amplitude TTL square wave is available at the TTL OUT BNC on the front panel. This

signal is unaffected by the AMPLITUDE, ATTENUATOR or DC OFFSET. TTL output is a

square wave for use in digital circuits, even though FUNCTION SWITCH is on sine or triangle

wave.

2) Considerations

CAUTION

KNOWLEDGE OF THE FOLLOWING FACTORS IS ESSENTIAL FOR PROPER OPERATION OF

THE INSTRUMENT:

A. The DC offset control can provide over ±10 volts open-circuited, or ± 5 volts into 50 load.

Remember that the combined signal swing plus DC offset is also limited to ±10 V open-circuited,

or ±5 V into 50 . Clipping may occur slightly above these levels. FIG 4 illustrates the various

operating conditions encountered when using DC offset. If the desired output signal is large or if

a large DC offset is used, an oscilloscope should be used to make sure that the desired

combination is obtained without clipping. Keeping the Amplitude control in the lower half of its

adjustment range reduces the probability of clipping.

B. To set the DC offset to zero or a specific DC voltage, depress the Function Switches slightly so

that all switches are released (all buttons out). This removes the signal from the output and

leaves the DC only. Measure the DC output on an oscilloscope or DC voltmeter and adjust the

DC offset control for the desired value.

TTL Pulse 0V

Triangle 0V

Sine 0V

Square 0V