A temperature invariant reference voltage and a temperature variant physical quantity, such as a voltage or current, are generated. The seats are mounted on a back of the LCD monitor. By operating any of the buttons during broadcasting of a program for broadcasting displayed as a play list, the take of the short sound assigned to the button can be superimposed on a signal being broadcasted. A voltage translator circuit is used to measure charging circuit output voltage and current over a plurality of incremental time periods during the charging period an calculate a signal proportional to changes in output voltage and current over the incremental time period.