This 1970 Electronic Design circuit uses a varactor or varicap. The circuit divides the frequency of a 150 MHz signal by 2. Similar versions appear on this site.
This simple logic level tester was found in Radio Electronics from the 90s. The inverters are of...
The low-noise amplifier shown uses a rare Raytheon operational amplifier today. The circuit can be...
This circuit, found in American documentation, works as a voltage doubler, enabling the supply of a...