Cheap eBay heater pad and its control circuitry. (with schematic)

These heating pads are very common on eBay. They consist of two sections of a resistive material and connecting strips sandwiched in a thick plastic document-style lamination.
The total thickness is just half a millimetre which is slightly disconcerting for a 240V heater. The power rating is determined by the area of the pad with suitably wider and longer heating sections.
The controller is just a very low power dimmer which is unlikely to actually be suitable for a 100W load as implied on its case.
These pads don't have any self regulation characteristic. They are basically just a flat flexible resistor.

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