Using the name of varactor this circuit was found in the Radio Electronics magazine of July 1982. Varicaps of any type can be used and the components selected according to the component.
This amplifier was found in a 70s documentation. The product gain x bandwidth is 350 MHz. The...
This circuit mimics the trill of a bird. We found it in an American documentation from the 90s. It is...
With the values indicated for this circuit, the lamp will flash 60 times per minute (1 per...