L=inductance of choke

RDC=DC resistance of choke

C=capacitance of filter capacitor.

Ideally, the resonance should be critically damped (Q=0.5), which can be achieved by adding external series resistance to the choke. Strictly, the load resistance across the capacitor also damps the resonance, and this may be transformed into a notional extra choke series resistance using:

Rnotional=LCRload

image

However, the damping effect of the load resistance is usually negligible. Even worse, a series voltage regulator is a constant current, or infinite, AC load to the smoothing circuitry, so it adds no damping whatsoever.

A typical traditional example: A choke input ...

Get Valve Amplifiers, 4th Edition now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.