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 light meter can be mounted with equivalent integrated circuit. The power is made by a single...
This integrated amplifier was found in an English magazine that no longer exists, from 1975. The...
This low-frequency circuit for alternating signals is from an early American 1980s documentation. The...