The integrated circuit used in this 70's application is not common today. The circuit consists of a small audio amplifier with few external components.
Found in an English documentation from 1977, this circuit activates a relay when the input voltage...
Found in an Electronic Design from the 90's, this circuit supplies voltages of 5 V and 3.6 V from...
This circuit was obtained from a 1962 magazine. It can still be mounted to be powered from 6 V...