This circuit uses a feedback integrator. We found it in Ferranti's transistor manual from 1974. Transistors are general-purpose types at the time.
This circuit was found in a Radio Electronics magazine from October 1987. It can be used as a...
This setting appears elsewhere on this site. This was obtained from an 80's Circuit Encyclopedia and...
This circuit was found in an Electronic Design from the 90s. The circuit uses a type J...