| 摘要 |
PROBLEM TO BE SOLVED: To reduce the power of a control circuit without damaging a user's visibility by equipping a control part for varying the brightness of an indication lamp for indicating the operating condition by a light emitting element. SOLUTION: A control part 8 is provided with P11 output terminal in addition to P10 output terminal for lighting a water heater lamp 7a. In the case of lighting the water heater lamp 7a by the P10 output terminal, voltage of about 5 V is applied to the lamp through the resistance of 1.5 kΩ, so that the current flowing therethrough is about 2.3 mA. In the case of lighting the lamp by the P11 output terminal, voltage of about 5 V is applied through the resistance of 16 kΩ, so that the current flowing therethrough is about 0.2 mA. According to the difference in current, the brightness of the lamp 7a is changed. The difference in power of a power supply part 10 between the case of driving the water heater lamp 7a about at 2.3 mA by the control part 8 and the case of driving the same about at 0.2 mA is about 0.4 W/h.
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