What type of waveform would you expect to see when measuring a certain junction of a switching power supply?

When measuring a certain junction of a switching power supply, you would expect to see a pulsating DC waveform that operates at a frequency higher than the line frequency. This is due to the operation of the switching power supply, which converts the input AC voltage to a higher frequency DC voltage for more efficient power regulation and output.

Switching power supplies utilize high-frequency switching techniques to minimize component sizes and losses. Unlike traditional linear power supplies that utilize line frequency (typically 50 or 60 Hz), the switching frequency of these power supplies often ranges from tens of kHz to several hundred kHz, depending on the design and load conditions.

The pulsating DC waveform you observe will have characteristics reflective of the high-frequency switching, providing a more efficient conversion and regulation process compared to line frequency. This is the reason why the waveform might appear as pulsating DC at a frequency significantly above the line frequency, thereby facilitating better control and output characteristics in the power supply.

In contrast, other types of waveforms would not accurately represent the junction’s output in a switching power supply context. For instance, filtered DC would indicate smooth, steady output without pulsations, whereas pulsating DC at line frequency would suggest a completely different type of converter that might be less efficient