Neon sign tube:
The construction & circuit diagram for neon tube is as shown in fig. Basically neon tube is used for advertisement or decoration purpose. The maximum length of tube is 8m. The available diameter for neon tubes are 5mm,10mm,15mm, 20mm, 30mm, etc. When the supply is switched on at primary, high voltage is induced in secondary winding of HT transformer. This voltage is applied across electrodes. At this high voltage, a discharge occurs in neon gas. In the neon tube, we can achieve various colours by changing the constituents of the gases and mercury filled in the tube. The choke is used for ballast & power factor improvement capacitor is also used. For the neon tube, continuous high voltage is required, so that following precautions should be taken.
* The neon tube should be installed by government authorized supervisor.
* The metal body of the HT transformer must be earthed separately.
* Caution notice of danger board is required.