Demagnetising circuit for colour TV CRT - connects capacitor to coil by relay whose excitation coil is connected to heating filament and transformer secondary tapping

摘要

The demagnetising circuit has the changeover contacts (a) of a relay (A) connecting the demagnetising capacitor (8) in one position to the demagnetising coil (11) and in the other position to a +700 V supply. The +700 V supply is drived from the receiver's +1100V supply using a two-resistor voltage divider (9, 10). The relay's excitation coil is connected at one end to the tube's heating filament (5) and at the other via a diode (7) to a tapping on the secondary winding (2) of the line transformer (1) (This secondary winding is coupled at one end to one end of the heating filament and at the other end via a diode and ballast resistor (4) to the other end of the heating filament).