The author sought to create authentic V-I plots for "The Secret Life of Circuits," eschewing common textbook "fake" diagrams. Capturing real data for semiconductor devices proved challenging due to minuscule currents, sudden current spikes, and temperature-dependent characteristics. Traditional oscilloscopes were insufficient; a benchtop multimeter (DMM) and pulsed power from a lab supply, coupled with non-conductive liquid cooling like mineral oil, became the preferred method.

To automate this tedious process, interfacing instruments with a computer via SCPI protocol is recommended. While the author's DMM supported SCPI, the power supply did not, necessitating the purchase of a Source Measure Unit (SMU). Despite initial documentation issues with the Rohde & Schwarz NGU401 SMU's Fast Log feature, particularly over USB, it was eventually made to work via Ethernet.

The implemented C code captures V-I curves, averaging data points for noise reduction and handling different current ranges. This method successfully generated plots for a 1N4148 diode, covering currents from microamps to nearly 2 A, revealing deviations from idealized models due to resistive effects. The same approach was applied to MOSFETs like the BS170, requiring additional ingenuity, such as series-connecting a traditional power supply and using pulsed signals, to capture data near breakdown voltages beyond the SMU's 20 V limit.