Found in old documentation, this circuit uses a double gate MOSFET. The operating frequencies depend on the coil, and the indicator is a microammeter.
This is one of the many versions of this circuit that appear on this site. We got it from an...
This General Electric circuit, in a documentation from the 1960s, allows the use of high...
This circuit was found in a 73 magazine for radio amateurs from the 90s. The circuit uses high...