Integrator with JFET (CB6229E)

This circuit was found in an 80s National Semiconductor documentation. The configuration holds true for modern JFETs.

Constant Current Source LM350 (CB15672E)
The current can be kept constant in the load circuit using the integrated regulator LM350. The...
RMS to DC Converter (CB6593E)
Found in older documentation this setting applies to modern components, noting that the power...
Frequency to voltage converter (CB6907E)
This circuit is suggested by American documentation from 1970. It makes use of transistors of the time...