Found in a 1967 American electronics magazine, this circuit has an input impedance of 2000 ohms. The circuit can be built with modern equivalent transistors.
This circuit is from a specialized documentation in 1992 FETs. The L1 coil has 0.07 uH with...
The LM1468L can also be used. The circuit is from Motorola's Linear Interface ICs and the...
This low frequency doubler requires a 50 mV signal at the input. The circuit is from an old...