This indicator or logic probe was found in the April 1979 Radio Electronics magazine. The integrated circuit is the 555 and the FET can be any general-purpose type.
This circuit was found in a 1980s documentation for amateur radio. The circuit is for 9 MHz...
This circuit generates a linear sawtooth signal. The circuit was found in the December 1992 issue...
I found this simple basic circuit of rhythmic light in a 1980 documentation. We warn you to be...