This circuit was found in a 1968 RCA documentation. The circuit can be designed with operational equivalents. Input signals can be up to 6 V in amplitude and the limitation is 78 dB.
Some of the components used in this circuit are not very common today. The circuit is from a 1996...
The existence of field effect transistors at the input of the integrated circuit (operational...
This circuit can use NTCs from 200 to 680 ohms, just change P2. For 200 ohms use 330 ohms, for 250...