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.
Here is an interesting circuit to be used in physics demonstrations involving energy...
This circuit, obtained from a 1978 publication, generates damped signals and can be used in...
We found this circuit in a manual of optoelectronics from Texas Instruments. In it photodiodes or...