This circuit, which uses a quadruple comparator, was found in old American documentation. The response curve is shown next to the diagram and can be adjusted in the trimpots.
This amplifier for hearing aid was found in a 1968 documentation using an integrated of the time....
We obtained this circuit from a 1993 documentation. The circuit has 9 current ranges that are...
In the figure we have the transmitter of a data transmission system with optical fiber suggested by...