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.
This circuit is from a Popular Electronics from the 80's. The components used are not common...
We found this Popular Electronics puma circuit from the 90s. Transformer T1 determines the...
This circuit produces a signal whose frequency decays from 500 Hz to zero in a time interval given...