Transformers and Capacitors

Inductance using transformers

Inductors exhibit significant dissipative effects, due to the long lengths of wire used to make them, and due to the magnetic losses of the core material. They also tend to generate "coupling" effects with interference from ambient electric or magnetic fields. It is impossible to create the ultimate transformer-based power filter, since the filtering of EM interference is intricately tied to the inductance of any surrounding EM field, the strongest of which is actually the one made by the transformer itself. To alleviate this, mumetal is used to block the magnetic field surrounding the transformer. Even in this "perfect" scenario, there are intrinsic losses due to hysteresis, causing compromises in the speed of energy transfer through a transformer. It is typical to see a 10 Volt voltage drop accross a 1:1 transformer.

Capacitance using capacitors

Ideally, a capacitor should be a purely reactive component, containing absolutely no power dissipative effects. Capacitors are generally purer reactive components than inductors. They tend to dissipate less power than an equivalent inductor. And, they are less prone to transmitting or receiving EM interference than inductors, because their electric fields are largely contained between their plates. The source of capacitor loss is usually the dielectric material used. Dielectric materials react to changing electric fields by producing heat. This heating effect represents a loss in power, and is equivalent to resistance in a circuit. In high end audio, this effect is undesirable, since we strive for the component to behave as a purely reactive circuit element. Electrolytic capacitors are, for example, notorious for their lossiness, due to both the characteristics of the microscopically thin dielectric film and the electrolyte paste used. Other materials are used to try to alleviate this lossiness in more expensive capacitors, such as paper and oil.