SRS Labs Lock-In Amplifier, SR530 manual There are four ways to set the frequency

the REF OUTPUT on the rear panel to the REF INPUT on the front panel. The REF OUTPUT is a 1 Vrms sine wave. The SINE OUTPUT may be used as the stimulus to the experiment. The SINE OUTPUT can be set to three amplitudes, 1 V, 100 mV, and 10 mV (rms) using the amplitude switch. The output impedance is 600Ω . The AMP CAL screw adjusts the amplitude.

The oscillator frequency is controlled by the VCO INPUT voltage. A voltage from 0V to 10V will adjust the frequency according to the VCO RANGE selected. Three ranges are available, 1 Hz/V, 100 Hz/V, and 10 KHz/V. The input impedance is 10 kΩ . The FREQUENCY CAL screw adjusts the frequency.

There are four ways to set the frequency:

1)Connect X5 or X6 (D/A outputs) to the VCO INPUT. The frequency can now be set from the front panel by setting the DISPLAY to D/A and adjusting X5 or X6. The frequency is also controllable via the computer interfaces by programming X5 or X6.

2)If the VCO INPUT is left open, then the oscillator will run at the top of its range (i.e. 10 Hz, 1 KHz, or 100 KHz).

3)A 10 KΩ potentiometer may be connected from the VCO INPUT to ground. This pot will then set the frequency.

4)Connect the VCO INPUT to an external voltage source which can provide 0 to 10V.

In all four cases, if the REF OUTPUT is connected to the REFERENCE INPUT on the front panel, the frequency may be read on the front panel REFERENCE DIGITAL DISPLAY or via the computer interfaces.

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