This circuit operates from 25 to 65 kHz depending on the transducer used and the settings. We found it in the Radio Electronics magazine of July 1985. The 9V to 12V power supply is not given.
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...