In the figure we have two circuits of limiters that provide the cut of the negative peaks of a signal. The circuit is from an 80's telecom documentation being adaptable on common receivers.
The circuit presented emulates an OR gate with the LM3900, operational transconductance amplifier....
This circuit was obtained from a 1962 magazine. It can still be mounted to be powered from 6 V...
The figure shows how to implement a conventional current monitor with differential amplifier on an H...