An oil strainer comprises upper and lower partial bodies, made of synthetic resin, joined together to form a roughly tube-shaped strainer main body, the interior of which is provided with a filter. The bridge switching circuit has a first power switch, a second power switch, a third power switch, and a fourth power switch. A large number of optical-signal interconnects may be provided among the components of the processor while using a small number of light transmitters andor light receivers. A third signal path connects a fifth external electrode to a sixth external electrode. The upper end of the male terminal is a round end. This circuitry is arranged to select for actuation an appropriate combination of these elementary stages according to the current absorbed from a load connected to the output terminal.