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.
A low frequency divider can be made using common unijunction transistors as shown by the figure...
This good quality audio amplifier with an output of about 10 W with the original transistor was...
This sophisticated sinusoidal audio signal generator uses a Wien bridge configuration with an...