| 摘要 |
A heating circuit for an electric blanket comprises two heating elements 1 and 3. One element (1) has a coaxial overheat sensing winding 2 such that the insulation between the windings will drop significantly if the element overheats. This element 1 is bypassed by diode 8. The protection winding 2 is connected via a diode 4, a resistor 5, and thermal fuse 6, to the pole of the supply opposite to that which feeds the protected element 1. In the event of overheat in the protected element, current will flow through resistor 5. The resultant heating of the resistor is used to trip the thermal fuse 6. The time for fusing is virtually independent of the position of the overheat in the protected element. The basic circuit can be adapted to use two protected elements and also to give three heat settings by the use of additional components. <IMAGE> |
