This circuit was found in the March 1984 issue of Radio Electronics magazine. The sensor is a transistor. The module is a common type at the time.
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,...