The figure shows how to use an operational circuit as a voltage divider. The circuit is from a Radio Electronics magazine from June 1986. The reference voltage is given by a zener diode.
Found in a 1960 Sylvania manual, this circuit can be implemented with a modern equivalent...
This configuration, already presented in other points of this section and website, is of a...
We found this precise crystal oscillator for the 144 MHz band, depending on the crystal used. The...