Simple switch for magnetisation coil of colour TV tube - has PTC or NTC resistor heating bimetal switching device and held in casing by spring clip

摘要

The switch has a PTC or NTC resistor thermally coupled to a switching device via a large-area centre electrode. The resistor is also connected to an outer electrode. The resistor heats the switching device, which then changes its state. The resistor, the switching device and the electrodes are located in a pot-shaped plastic moulded casing (26) having a slot in one wall through which the connection tags (4,5,49) of the centre electrode (7) and the outer electrodes (8,50) project. A spring clip (51) closes the casing and is U-shaped with hooks at the ends of its limbs that locate around inward-sloping ledges at the closed end of the casing. The clip's spine is shaped so as to increase the force with which it acts on the resistor (15) and the switching device (16). The bracket may simultaneously act as one of the two outer electrodes, in which case it has a connection tag. The switching device may be a bimetal strip or a ceramic resistor heated by the first resistor. Variants of the basic switch are described. The advantage lies in the extremely simple components employed and their assembly.