| 摘要 |
<p>A timing device for timing the cooking of foods by immersion in a heated cooking medium, such as shortening. The timing device uses a voltage controlled oscillator and associated counter. The base frequency of the oscillator is set by the charge on a capacitor of an RC timing circuit. A thermistor measures the shortening temperature and produces a voltage that varies the frequency of the oscillator, with higher temperatures causing higher frequencies. When the counter has received a predetermined number of pulses, it actuates a warning system indicating cooking is completed. Oscillator frequency varies as a logarithmic function of the thermistor voltage, and required cooking time is a logarithmic function of cooking temperature. Consequently, operations on the proper portion of the respective curves assures uniformity of cooking. Gang switches selectively connect different resistors into the RC timing circuit to vary cooking time for different foods. The timing device may also operate in parallel for multiple cooking units, utilizing the same warning signal system. Comparative output voltages from the thermistor are also used to actuate lights when the shortening reaches the desired temperature for cooking and to actuate an overheat warning circuit.</p> |
