We found this circuit in a 90's EDN. The circuit is based on a control integrated that is still common in these types of applications. The circuit uses a PROM.
The figure below shows an AC transconductance amplifier with the National Semiconductor LM3900. The...
This common circuit using operational amplifiers was found in the 1993 issue of Radio Electronics Special...
This circuit provides a voltage at the output only when the input voltage exceeds a value that...