| 摘要 |
An aquarium water heater having a heater element energized by first and second silicon-controlled rectifiers connected in parallel in opposing conductive relation, one rectifier providing energy to the heater element on one-half cycle of alternating current while simultaneouly charging a capacitor which is connected to the gate electrode of the second rectifier for rendering the second rectifier conductive on the other half cycle of alternating current to supply energy to the heater element. Circuit means are connected to the gate electrode of the first rectifier, the circuit means including a thermistor for sensing the water temperature and rendering the first rectifier non-conductive when the water temperature equals a set point determined by a rheostat in the circuit means.
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