Using a sensitive crystal or ceramic microphone, this circuit can pick up faint sounds through a wall. The circuit has a good range given the use of an RF amplifier transistor.
This circuit was obtained in a 1986 documentation consisting of an active frequency divider for...
OSEPP makes available through Mouser Electronics a series of 100% Arduino compatible robotic kits. The...
We found this circuit in a 1977 National Semiconductor audio manual. The integrated circuit is the...