| 摘要 |
<p>955,707. Automatic control of temperatures. TYER & CO. Ltd. May 29, 1961 [June 3, 1960], No. 19702/60. Heading G3R. An instrument for controlling and indicating a desired temperature comprises a centre-zero millivoltmeter movable with the slider of a resistor forming one arm of a temperature-measuring Wheatstone bridge. As shown, Fig. 5, a bridge comprises a desired temperature setting resistor 4A and a temperature responsive resistor 14. Out-ofbalance of the bridge is indicated by a centre-zero millivoltmeter 5A and the out-of-balance signal is fed through a transistorised amplifier comprising stages 9-12, to actuate a relay 13 energizing a temperature regulating means, not shown. Positive feedback is applied from stage 12 to stage 9 from a potentiometer R2, and the input of stage 9 is balanced by a potentiometer R1 having a slider connected to the negative supply through a resistor R6. The relay 13 is slugged by a capacitor C3. The meter 5A and the resistor 4A are mounted concentrically in a case 1A, Fig. 2, and a slider 4 of the resistor 4A is mounted on a pointer 3G for setting the desired temperature on a scale 3. The meter 5A is mounted on the pointer 3G and has a pointer 5B to indicate derivation of the measured temperature from the desired value.</p> |
