Found in a 1980s telecommunications documentation, the circuit presented acts as a product detector. The modulator or mixer in the square may be that of the previous circuit.
This circuit is from the 1990 Motorola Linear Databook. The circuit can be applied to other...
Found in a 90's EDN this circuit can be used as a shield. The transistor is a general-purpose type and the...
Suggested by Harris in documentation from the 80s, this circuit uses components from that time. It...