| 摘要 |
1,227,723. Switching arrangements; control of motors. HORSTMANN GEAR CO. Ltd. 8 Dec., 1969 [24 Jan., 1969], No. 4087/69. Headings H2H and H2J. In a two-state switching system which is operable by the change in resistance of a sensor of an environmental condition a compensating resistor is added to the sensor resistance in one of the two states so as to decrease the operating differential. The system is as described in Specification 1,195,337 with the addition of a resistor 21 which is placed in series with the sensor 1 in one position of a switch 18, which is coupled to switch 8, so that, for a given value of the sensor resistance, the heater 2 of bimetallic switch 4 receives the necessary different current to switch on than to switch off. The sensor may be a photo-cell controlling street lighting, which is thus switched at the same level of light at dusk and dawn. |
