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.
An article in Radio Electronics magazine from November 1962 taught how to connect two common...
In the figure we have the way to use the transistors of an old-paired pair as a trigger circuit. The...
This amplifier is from Motorola documentation from the 70s. The circuit uses transistors from the...