This configuration with the LM111 was found in your factory manual. The circuit can be implemented with modern operational equivalents. The power supply must be symmetrical.
This circuit was found in a 1965 General Electric publication. The circuit can be adapted to...
This configuration of the 1980s uses NAND A-type CMOS ports, which have a linear response with...
This circuit can be made usng the TIP32 transistor but must use carbon microphone (not very common these...