CRT Degauss for Wide Range Input Voltage Supply
Original Publication Date: 1986-Nov-01
Included in the Prior Art Database: 2005-Mar-09
In a CRT color display, a degauss coil requires a high initial AC current for degaussing, decaying to a very low residual current. The circuit disclosed operates over a wide range of AC input voltage by using a thermistor (negative temperature coefficient) across the coil, a positor (positive temperature coefficient) in series with the coil, and a heater across the AC supply. As these three components are in thermal contact, a high initial current decays to a very low residual current as the temperature increases. The above diagram shows the circuit used. Across the degauss coil is thermistor R-, and positor R+ is in series with the coil. In parallel with this combination is heater RH. The AC input supply is connected across RH.