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.
We found this automotive alarm circuit in a 90's Popular Electronics circuit. The circuit emits a...
Figure bellow shows how the 4510, a divide-by-1U, up/down counter with three-state outputs is...
This old oscillator using germanium transistors has a high impedance headphone as inductor to...