A light source apparatus includes an outer casing. The bi-polar transistor 200 and the field effect transistor 100 are formed in the same element forming region 16. The variable-reactance circuit can comprise one or more reactive elements all connected to a first terminal and selectively shorted to a second terminal via a switch. The mesh layer may be positioned beneath the housing and may define a plurality of spaces. The method can be used for power converters, control devices or protection relays for shunt capacitors or filters used in power systems. The frequency detection circuit is further operative to generate a control signal to reduce a sampling rate of the received signal in response to a predetermined number of the sequential samples having a same value.