In Last power-amp lecture, I posted an I-vs-V plot for the LM2903 comparator’s open-collector output, which I had made sometime in 2013, I think:
I decided to redo the plot using the Analog Discovery~2, as I now include the open-collector curve in the textbook (in an optional section, since we no longer use open-collector comparators). I used a 12V wall-wart and both the function generator and oscilloscope functions. I used the “custom channel” and XY plot features to get the I-vs-V plot on the screen (though I saved the data and replotted with gnuplot, to superimpose different runs). I also averaged 10 sweeps to reduce noise.
The triangle-wave generator and the nFET makes a variable load for the comparator, from slightly more than R1 up to about 1MΩ.
The results with the Analog Discovery 2 are much cleaner than my old results, which were most likely done with an Arduino, which has a very low resolution ADC.