In the design of a power supply, the designer must be careful of resonance effects because the ripple voltage could build up to a high value. The components that must be carefully selected are:

In a power supply filter, the first choke and the first capacitor form an LC circuit that can resonate at certain frequencies. If the ripple frequency from the rectifier happens to match or be close to the resonant frequency of this LC combination, the ripple voltage can build up to destructive levels. To prevent this resonance effect, designers must carefully calculate and select the values of the first choke and first capacitor. They are chosen so that their series resonant frequency is well below the primary ripple frequency of the power supply. The other components, such as the bleeder resistor or a second capacitor, are secondary to this effect; the primary resonant circuit that directly interacts with the rectifier's immediate ripple output is formed by the first choke and first capacitor.