Abstract: A low-pass filter having, a parallel circuit of a first coil and a first capacitor disposed between an input terminal and an output terminal; and a second capacitor disposed between the input terminal and ground. Also included is a third capacitor disposed between the output terminal and ground, and a power detection coil magnetically coupled to the first coil, both ends of which are detection signal output terminals. Therefore, the low-pass filter enables a decrease in the number of mounted parts in a high-frequency transmission circuit of a digital portable telephone, thereby miniaturizing the circuit and reducing the costs.

Abstract: A display device of a storage battery for optically displaying a condition of an electrolytic solution stored in a casing of the storage battery comprises a pillar member having a transparent body having one end and other opposite end, the one end of the pillar member being engaged at an upper surface of the casing in a usable state so that the other opposite end thereof projects into the casing. An inclined end surface of the opposite end side thereof is inclined to a side surface of the pillar member at a predetermined angle so that an incident light transmitting from the one end side thereof permeates through the inclined end surface or is reflected thereby according to the condition of the electrolytic solution which is in contact with the inclined end surface.