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Fluorescent Tube Starters

There are two types of starters, the glow starter and the thermal starter. The glow starter starts with its contacts open and closes once the bi‑metallic strip has warmed up via the glowing neon. Whereas the thermal starter starts with the contacts closed and has a heater which warms up the bi‑metallic strip, which then opens and stays open because of the heater.

The standard glow starter with its neon and capacitor is shown in the picture to the left. The bi-metal contact on one of the electrodes in the neon can be clearly seen. The capacitor is used to reduce radio interference when the bi-metal contact switches.

The Experiment

A quick and simple experiment that you can do with a starter is, first take the cover of a starter so as to expose the internal parts, then connect it in series with a 4k7, 12W resistor to the mains. You will see that after a few seconds the neon starts to flash randomly. From the picture you can see that I used flying leads with insulated crocodile clips to connect up my circuit. Now replace the resistor with a 10‑14W incandescent bulb and the bulb will seem to flicker randomly too.

NOTE: How the 5W resistor is discoloured from over heating.

************ WARNING: YOU DO THESE EXPERIMENTS AT YOUR OWN RISK ************
**** EXTREME CARE MUST BE TAKEN WHEN WORKING WITH HIGH VOLTAGES ****

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