This circuit was described in an article in the February 1993 Radio Electronics magazine. The frequency depends on the crystal and L1 is optional.
We found this circuit in a Poptronics of February 2000. We can do its assembly using 4 1N4001...
We found this circuit in an old oscilloscope publication. With it, it is possible to observe the B...
This flasher with two power transistors was found in a Radio Electronics magazine from September 1961....