Do you know what a CRT is? A cathode ray tube. It's what they used to use in an analog TV. The electron beam was made to scan across the screen, and from top to bottom by using a magnetic field just beyond the electron gun. You would have a coil on the left and right for horizontal deflection, and top and bottom for vertical deflection. The deflection coils would be connected in series and to their respective drivers.what is a deflection coil??