This simple circuit with a 5V regulator was found in an American documentation from the 90's. The output voltage is adjusted in a trimpot.
This circuit of a 1964 Electronic Design uses a photodiode from the time. Modern equivalent can be used....
This VCO or Voltage Controlled Oscillator was found in a Popular Electronics from 1991 but can be...
We found this circuit for an anti-theft radar that operates at 400 MHz in a Radio Electronics from...