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 circuit was obtained in an English publication from 1981. The 7555 is the CMOS version of the...
This intercom for the 27 MHz band was found in a recent English documentation, working with a...
We found this circuit in an old Popular Electronics. The circuit can be applied to other...