Found in American documentation from the 1980s, this circuit has a diode feedback. At the exit we have an indicator LED. The LM3900 is a transconductance operational amplifier.
We found this circuit in an old publication. The components used are rare today. Accuracy depends on...
This TTL circuit has a well-known configuration, having been found in a Radio Electronics magazine...
The circuit shown in the figure was suggested by National Semiconductor in its 1994 Linear...