Found in a Popular Electronics from the 90s, this circuit uses components that are still current. The circuit triggers the vehicle's horn. The sensors can be increased in number.
This circuit was found in a 1966 EEE. What it does is it converts the logic levels of 0 V and +4 V...
This circuit is from a 1976 documentation. It makes use of isolated gate MOSFET which is already very...
This interesting effect circuit was found in a 1982 publication. The sequence of musical notes is...