š Key Concepts
ā¢ Typical functions of each stage in a linear DC power supply: transformer, rectifier, filter, and regulator
ā¢ Where the main voltage step from 120 VAC down to a level suitable for 24 VDC usually occurs
ā¢ How much voltage change is caused by a transformer turns ratio versus the smaller drops across diodes, filters, and regulators
š Think About
ā¢ Look at what is connected directly to TP1 and TP2 and ask: does this stage mainly change voltage level or just change waveform shape/ripple?
ā¢ Compare the approximate voltage at the secondary of T1 with the regulated 24 VDC output: which block boundary contains that big reduction?
ā¢ For blocks B, C, and D, think: are these stages mainly rectifying, smoothing, or fine-tuning the voltage, and how large is the typical voltage drop of each?
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Before You Answer
ā¢ Identify which labeled section contains the transformer T1 between primary and secondary windings
ā¢ Estimate which section is responsible for the largest RMS voltage difference between its input and output, not just removing ripple
ā¢ Confirm that drops across diodes, filters, and the series pass transistor are relatively small compared to the primary step from 120 VAC to a low AC voltage feeding the rectifier