We found this circuit in a 1965 Electronic Design. Transistors are still common but admit equivalents for some of them. The circuit drains a current of only 4 mA.
We find this circuit in a 1980s documentation. The integrated circuit used is unusual today. The...
This circuit uses a feedback integrator. We found it in Ferranti's transistor manual from 1974....
I found this simple circuit from an English magazine from 1984. The circuit can be easily...