Electronic starter for neon tubes

Electronic starter for neon tubes shown in the diagram below , is constructed using triac Y1112 produced by Texas Instruments , which is specially designed to turn a thyristor fluorescent tubes .
Its main advantages over a standard thyristor latching current is much higher, ability to work at quickly increasing cathode - anode voltages ( high value of du / dt), and overvoltage protection .
This property makes the electronic starter for neon tubes to be ideal for replacing classic starter, with a view to secure lighting without flickering and a long life .

Normally, high voltage of starter is achieved by interrupting current through a shock coil. All are usually made by starter , which ensures the emergence of a large enough current through the tube filaments , which causes heating tube ends , facilitating the ignition.
When connecting the mains voltage , Th2 “priming” through R1 and R2.
Through tube filaments will appear a quite high current , so it will preheat .
Due to voltage drop on diodes D7 and D8 , capacitor C1 will charge through resistors R4 and R5 . When capacitor C1 loaded to a certain value , enter the conduction thyristor Th1 and interrupt gate current of Th2. Abrupt interruption of a relatively high current make that shock to generate a reverse voltage high enough to ignite the fluorescent tube .