We found this circuit in an English publication from 1969. The circuit uses transistors from the time and can operate at frequencies up to 300 MHz. Observe the waveforms of the obtained signal.
In the figure we have the way to activate a red LED that needs 1.7 V or even others with higher...
This circuit was obtained in a 1979 publication, but it can be assembled with the BD135 instead of the...
Found in Radio Electronics from the 90's, this circuit employs a 3140 operational amplifier, still...