This circuit is from an old Popular Electronics, but it can be easily implemented nowadays, even adapted to act as a shield. The circuit has the frequency given by C1 and adjusted in R1.
This circuit was found in a 1980s English documentation. It is intended for old xenon lamp...
This circuit was found in the July 1990 Radio Electronics magazine. It is based on the 3-digit...
This circuit can be found in a 1970 Motorola documentation. The circuit can be implemented with general...