This CW circuit was found in a Radio Amateur Today from the 890s. The CMOS circuit must be powered by an isolated source and has different dash and dot timings.
We found this circuit in the 1994 Linear Applications Handbook from National Semiconductor. The...
This variac was found in an old documentation, but it has a current circuit, just using triac of...
This circuit is from an old 80's linear circuit manual. The configuration can be implemented with modern...