This simple circuit, found in American documentation, uses only one relay that locks when any of the sensors is activated. To reset, simply turn off the power for a moment.
27 MHz Transmitter (CB14008E) This circuit was found in a Japanese publication from the 1970s. The...
This circuit reproduces in a small loudspeaker the sound of the signal that modulates a...
The integrated circuit used in this multivibrator is no longer common today. With the components...