| 摘要 |
The bobbin (1) has a horizontal core tube (10) of an electrically conductive material. At least one relief section (7) is at the bobbin (1) core (2), of an electrically conductive material, which can be covered wholly by an insulating yarn or filament wound round the bobbin when it is full, and which is exposed when the bobbin is nearly empty as the windings are consumed. The relief sections (7) are electrically connected to a conductor support (10) when the bobbin (1) is mounted to it. A moving conductive blade (16), also mounted to the bobbin support (10), rests against the bobbin windings when the bobbin is full, and makes contact with the relief sections (7) when the bobbin is nearly empty, to close an electrical circuit. A lamp system (13) registers a closed electrical circuit.
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