We found this circuit in a 1964 Electronic Design. The components are from that time, but the circuit can be made with modern equivalent components.
This circuit was found in a 1980s documentation. It decodes by identifying a certain frequency tone...
This circuit was found in a documentation by A. Fanzeres making use of a grounded metal housing...
We can obtain the characteristics of an operational amplifier with FET by adding FETs common to the...