Varactor diodes are our varicaps of today. This circuit for switching signals in an RF circuit was found in a Radio Electronics magazine from July 1982.
This circuit uses two Raytheon RC4558 operational amplifiers that are similar to the 741. The...
This small stereo amplifier for headphones was found in a documentation on integrated circuits from...
This is a MOSFET version of a grid dip meter for frequencies between 1.8 MHz and 150 MHz,...