This simple general-purpose transistor mixer was taken from an article in Electronics Now magazine in March 1994. You can choose a low-noise transistor such as the BC549.
This circuit uses separate sources for the power supply and the operational stage. The output...
This is a MOSFET version of a grid dip meter for frequencies between 1.8 MHz and 150 MHz,...
Found in the March 1974 Radio Electronics magazine, this circuit is designed to measure the level...