This circuit is from a Hands-On Electronics from the 90s. The integrated amplifiers used are well known. The range is a few tens of meters depending on the resistance of the cables.
This circuit, which can also be adapted to function as a microcontroller shield, is from 2003...
This sensitive circuit was found in an Electronics Hobbyists Handbook from the 1990s. The circuit can...
This circuit can be used with 3 receivers and is intended for low frequencies (medium wave range). We...