This alarm circuit has a trigger delay system. The circuit was found in a Popular Electronics of the 90s. The components are common.
This preamplifier is recommended by Sanyo and is based on its LA3160 integrated circuit. The...
This circuit, obtained in a 1981 English magazine, is nothing more than a sound switch. Placed near...
We found this circuit in an old publication from Argentina. The relay must be of the sensitive type,...