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I attempted to measure the voltage output of a Gauss meter by Polytronics (GM-504) using a lock-in amplifier (SRS-830). The measurement setup was configured by connecting the output low of the Gauss meter to the ground and the output high to the signal input (AUX) at the rear panel of the lock-in amplifier. However, the lock-in amplifier displayed significant noise in the signal.
Assuming that the noise might be caused by connecting the output low of the Gauss meter to the ground of the lock-in amplifier, I introduced a differential amplifier circuit using the OP07CP operational amplifier. The Gauss meter output voltage was given as the input to the differential amplifier circuit, and the output of the differential circuit was fed to the lock-in amplifier input. However, the noise issue still persisted.
To further isolate the ground-related noise, I powered the differential circuit with two 9V batteries instead of a current source, creating a dual power supply. The batteries were connected in series, with their midpoint serving as the ground reference for the differential circuit. Despite this approach, the noise problem remained unsolved.
I am confident that the analog-to-digital converter (ADC) of the lock-in amplifier is functioning correctly, as I have previously measured the voltage output of a photodiode amplifier with the same lock-in amplifier without significant noise.
What could be the possible reason for the noise when measuring the Gauss meter output, and how can I effectively eliminate this issue?
Assuming that the noise might be caused by connecting the output low of the Gauss meter to the ground of the lock-in amplifier, I introduced a differential amplifier circuit using the OP07CP operational amplifier. The Gauss meter output voltage was given as the input to the differential amplifier circuit, and the output of the differential circuit was fed to the lock-in amplifier input. However, the noise issue still persisted.
To further isolate the ground-related noise, I powered the differential circuit with two 9V batteries instead of a current source, creating a dual power supply. The batteries were connected in series, with their midpoint serving as the ground reference for the differential circuit. Despite this approach, the noise problem remained unsolved.
I am confident that the analog-to-digital converter (ADC) of the lock-in amplifier is functioning correctly, as I have previously measured the voltage output of a photodiode amplifier with the same lock-in amplifier without significant noise.
What could be the possible reason for the noise when measuring the Gauss meter output, and how can I effectively eliminate this issue?
