Found in an ancient American documentation, this circuit can generate signals up to 40 MHz for a Z80, microcontroller widely used at the time. The circuit must be powered with 5 V and also serves as a shield.
This circuit is from the datasheet of STMicroelectronics, being indicated for the voltage...
In this circuit the CA3140, an operational amplifier, is used as a comparator with the zener diode...
We found this voltage regulator for 5 V with current up to 10 A in an old manual of integrated circuits....