Found in an Electronic Engineering from the 80's, this circuit makes use of components of the time. The circuit can be implemented with modern equivalent components.
This circuit is from the time when photos were revealed in darkrooms. We found it in a 1968...
With the use of a very sensitive and lockable relay this circuit can be used in intervals of 15 to...
This circuit was found in the April 1971 Radio Electronics magazine. The transformer is the type...