This circuit can be used in a signal level indicator with LEDs. The circuit is from an Electronics Now dated January 1996. The power supply must be dual.
This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent...
The LEDs act as diodes, so if good they will show the same characteristic curve. Arrangment shown...
We found this circuit in an ancient American documentation. It can be adapted to operate in other...