Found in Motorola documentation from the 90's, this circuit has a high input impedance. The power supply must be symmetrical. The circuit can be implemented with modern operational amplifiers.
This 1974 circuit uses two 555 integrated circuits in a very traditional configuration. The...
This circuit was found in Electronics Now magazine and can be applied to any JFET. The circuit has high...
The receiver shown above was sent in by contributing reader Adriano Muniz Moura and is used for...