This circuit with pressure sensor was obtained from the Encyclopedia of Electronic Circuits volume 5 of 1995. Note the construction of the sensor with rubber and conductors.
This circuit, which presents a certain danger and should be used with caution, was found in the...
This circuit with variable capacitance diode (varicap) is from a publication from the 90s. The...
This circuit, shown in the figure, consists of a variable gain amplifier with differential input...