This approach alarm circuit was found in the September 1970 Radio Electronics issue. The 1 mH coil is wound on a ferrite rod. The relay is 12 V sensitive.
The given number circuit is used to activate the relay by interrupting the light beam that hits...
In the figure we have a simple and efficient way to obtain rectangular signals from an astounding 555...
This circuit, for 78xx series integrated devices, is suggested by Motorola in its 1990 Linear...