Integrator with JFET (CB6229E)

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

Digital Coded Keyboard (CB18722E)
We found this code key or coded keyboard in a publication from the 90s. The circuit uses...
Complementary Dimmer (CB20708E)
With this circuit, using a single control voltage, you can increase the brightness of the lamp...
1 kHz Bandpass Filter with the 741 (CB13570E)
This circuit is from a 1976l filter cookbook. The circuit has a factor Q = 3, and must be supplied...