| 摘要 |
PURPOSE:To avoid the variation of brightness of a display element and to attain transmission of many control signals by providing a constant current circuit to a main body side control circuit together with a series circuit of the display element and a variable resistance circuit added to a remote control side operation circuit and supplying the output current of the constant current circuit to said series circuit via two remote control lines. CONSTITUTION:A fixed current is supplied to a series circuit of a display element 22 and a variable resistance circuit 23 of a remote control side operation circuit 2 from a constant current circuit 7 of a main body side control circuit 1. Then the 2nd switch 25 of the circuit 23 is opened and closed during operation of a hot water supplier 27 where the 1st switch is opened. As a result, the brightness of the element 22 has no change even though different temperatures are set at the circuit 2. Furthermore the voltage change of the circuit 2 is detected by a voltage comparator 8 of the circuit 1. then the control signal can be transmitted in an inexpensive constitution using two remote control lines 3 and 4. Thus the wiring construction is also simplified.
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