In this interesting circuit from Popular Electronics, the output voltage is the square root of the input voltage. Equivalent operational amplifiers can be tried out.
This is the circuit of a sensitive voltmeter using a difficult-to-obtain 5 uA full-scale...
This was the original title given by the publication of the 80s in which we found it. Similar...
When the VCR is turned on, the TV is automatically activated. This circuit of an old project...