This circuit is from a 1970 General Electric documentation. It can be found with variations on this website. The components used are common today.
This circuit can use NTCs from 200 to 680 ohms, just change P2. For 200 ohms use 330 ohms, for 250...
This circuit was found in an Electronic Design from the 90's. It makes use of components from the...
This circuit for a frequency of 40 kHz was found in an old Electronic Design. There were no...