This automotive circuit was obtained from an 80's schematic from the integrated circuit factory itself. The voltage regulator is still common, but the operational amplifier is of the time.
This circuit was found in a 1970s General Electric documentation. This circuit already used an...
This circuit was published in Popular Electronics from the 90's. The components are common, as...
This simple unijunction circuit is from a Radio Electronics from July 1963. It can be assembled with a...