This can be considered a complete laboratory for the repair professional. A full featured signal tracer with 13 tubes. The circuit is from the March 1946 issue of Radio Craft.
This circuit was found in English documentation from the 90's. Transistors are general purpose types....
This instrumentation circuit is from the June 1986 issue of Radio Electronics magazine. Equivalent...
This is an interesting idea that we found in the May 1971 issue of Radio Electronics magazine. It can...