Like the previous circuits, this one uses a small speaker as a microphone and has two amplification stages with 600-ohm output.
For the NOR or no-OR function (negative of the OR function) we take the previous configuration (CB15067E)...
We found this circuit in the October 1996 Electronics Now magazine. The circuit uses LDRs as...
We find this circuit in an American 80's documentation. It makes use of IC sensor which is mounted...