This circuit was found in a PE Hobbyst Handbook of 1989. It uses a black light fluorescent of the time. Small fluorescent black light from 1 to 4 W can be used.
This ultra-low noise circuit was found in the May 1990 issue of Radio Electronics magazine. The...
The sophisticated signal tracker/follower with a JFET and integrated circuit 741 was found in a...
This two-transistor limiter for low-frequency signals was found in the May 1963 Radio Electronics...