This alarm with sensors in series and parallel was found in the 1995 Encyclopedia of Electronic Circuits. The number of sensors can be changed at will.
Originally this circuit excites an incandescent lamp, but it also serves for LEDs, if they use a...
Found in National Semiconductor documentation from the 1990s, this circuit corrects the curvature of...
In fact, the 556 consists of a double 555, which can be replaced by these integrated ones. The...