Abstract: A telemetering system allows a receiver to provide an indication related linearly with the data from a sensor in a transmitter that comprises an amplifier composed of relatively inexpensive and low-quality parts. The transmitter includes an ID ROM (10) that stores an ID code specifying itself, and it transmits the ID code when transmitting the output from a sensor (1). The receiver includes a correction circuit (13), which finds the correction table corresponding to the transmitter in accordance with the received ID code and corrects the received sensor output on the basis of the correction table.

Abstract: A power system the size of which does not become very large although the system uses secondary batteries, and in which the supply of DC power is not stopped at the time of charging the battery after the secondary battery is completely discharged, and an amplification system for audio using the power system. When no signal is inputted to an amplifier (1) for audio for a fixed period of time or longer, a control circuit (4) gives a connection switching signal (b) to a connection switching circuit (7) under a fixed condition, but, Whenever the signal (b) is given to the circuit (7), one of the secondary batteries (6A and 6B) is switched to the power source of the amplifier (1) from a state where the battery is charged by means of a charging circuit (8), and the other battery is switched to a state where the battery is charged by means of the circuit (8) from a state where the battery supplies electric power to the amplifier (1).