This circuit with different colored indicator LEDs has an expanded scale. We found it in the March 1992 Radio Electronics magazine. For an adjustable range of 0 to 10.5 V.
The XR2206 is not a common component today, but if you have one you can build this function...
With the precision given by the crystal this circuit provides signals of several frequencies for the...
This circuit with a MOSFET is from an old American documentation. The capacitor should be leak...