Regulated power supply

A regulated power supply is an embedded circuit; it converts unregulated AC (alternating current) into a constant DC.

The output from the regulated power supply may be alternating or unidirectional, but is nearly always DC (direct current).

[1] The type of stabilization used may be restricted to ensuring that the output remains within certain limits under various load conditions, or it may also include compensation for variations in its own supply source.

Variable bench power supplies exist both as linear (transformer first) and switched-mode power supply (full-bridge rectifier first), each with a different set of benefits and disadvantages: The linear type produces only very little noise (or "ripple voltage") and is less prone to external electromagnetic and radio frequency interference (EMI, RFI), making it preferable for audio equipment and radio-related applications and for powering delicate circuitry.

[5] Linear power supplies also have fewer failable parts which increases longevity,[a] and have a quicker transient response.

Linear variable bench power supplies have existed since longer ago, dating back at least to the 1980s.

This is done to reduce energy wasted to heat by widening or narrowing the selected section of the secondary side of the transformer to be as close above the user-selected output voltage as possible.

The higher efficiency means less heat production at the same output power, thus less wasted energy and needed cooling.

Similar switching technology is used in AC adapters that charge battery-powered devices including mobile phones, laptop computers, and electric bicycles.

[18][19] Bench power supply units equipped with an integrated voltmeter panel to measure external voltages have existed in the 1990s and possibly earlier, but portable multimeters have made that feature obsolete.