Trigger

Refer to Figure 2-6 for location of items 23 through 31.

(23) EXT INPUT Connector—Provides a means of introducing external signals into the trigger generator.

(24) EXT COUPLING Switch-Determines the method used to couple external signals to the Trigger circuit.

AC—Signals above 60 Hz are capacitively coupled to the input of the Trigger circuit. Any dc components are blocked, and signals below 60 Hz are attenuated.

DC-All components of the signal are coupled to the trigger circuitry. This position is useful for displaying low-frequency or low-repetition-rate signals.

DC-MO—External trigger signals are attenuated by a factor of 10.

(25) SOURCE Switch-Determines the source of the trigger signal that is coupled to the input of the trigger circuit.

(26) INT Switch-Selects the source of the triggering signal when the SOURCE switch is set to INT.

CH 1—The signal applied to the CH 1 OR X input connector is the source of the trigger signal.

VERT MODE—The internal trigger source is determined by the signals selected for display by the VERTICAL MODE switches.

CH 2—The signal applied to the CH 2 OR Y input connector is the source of the trigger signal.

INT-Permits triggering on signals that are applied to the CH 1 OR X and CH 2 OR Y input connectors. The source of the internal signal is selected by the INT switch.

LINE—Provides a triggering signal from a sample of the ac-power-source waveform. This trigger source is useful when channel-input signals are time related (multiple or submultiple) to the frequency on the power-source-input voltage.

EXT—Permits triggering on signals applied to the EXT INPUT connector.

3397-07

(2?) LEVEL Control—Selects the amplitude point on the trigger signal at which the sweep is triggered.

(28) TRIG'D Indicator-The light-emitting diode (LED) illuminates to indicate that the sweep is triggered.

(29) SLOPE Switch—Selects the slope of the signal that triggers the sweep, (also refer to TV Signal Displays at the end of Section 2).

Sweep is triggered on the positive-going portion of the trigger signal.

Sweep is triggered on the negative-going portion of the trigger signal.

(30) MODE Switch-Determines the trigger mode for the sweep.

AUTO—Permits triggering on waveforms having repetition rates of at least 20 Hz. Sweep free-runs in the absence of an adquate trigger signal or when the repetition rate is below 20 Hz. The range of the TRIGGER LEVEL control will compensate for the amplitude variations of the trigger signals.

NORM—Sweep is initiated when an adequate trigger signal is applied. In the absence of a trigger signal, no baseline trace will be present. Triggering on television lines is accomplished in this mode.

TV FIELD—Permits triggering on television field-rate signals (refer to TV Signal Displays at the end of Section 2).

Figure 2-6. Trigger controls, connector, and indicator.

VAR HOLDOFF Control—Provides continuous control of holdoff time between sweeps. Increases the holdoff time by at least a factor of four. This control improves the ability to trigger on aperiodic signals (such as complex digital waveforms).

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