Insight - How Tubelight Starter works
A starter incorporates a small gas filled tube and a RFI (Radio Frequency Interference) suppression capacitor (Also see Capacitor-Insight). Both the capacitor as well as neon gas filled tube are connected in parallel with tube light circuit.
The small glass tube is filled with neon or argon and contains a bi-metallic plate. This bi-metallic plate is the heart of the starter. Among the two contact strips shown in the image, left one is attached with the bi-metallic strip as shown in the above image.