Demagnetising circuit for colour TV receivers tube - has series LC circuit shunted by semiconductor switch connected via resistor network, producing grid voltages for triple beam tube

摘要

The demagnetising circuit has the demagnetising coil (13) in series with a capacitor (12). This series combination is shunted by a bidirectional controlled semiconductor switch (14) and is connected at one end (capacitor end) via a resistor network (7-11) to a tapping on the winding (6) of the line transformer supplying the rectifier cascade (3) that generates the high voltage for the tube (5). The semiconductor switch consists of a thyristor (15) shunted by an antiparallel diode. The resistor network is used to produce the grid voltages for the tripple beam tube. The switch closes once the capacitor has been charged. This switch may also be constructed from relay contacts.