This alarm goes off if someone leaves a door open. We found it in the Encyclopedia of Electronic Circuits Volume 5 from 1995. The circuit uses components that are still common today.
This oscillator circuit with two transistors is from a 1965 documentation. The circuit is of the...
This circuit was obtained in an old documentation, but it is still current by the used components....
This guitar effect pedal was found in 1982 documentation. The circuit can be easily assembled with...