This circuit uses only transistors and was found in a 2003 documentation. Transistor 2N3055 must be mounted on a heat sink and the voltage is set to R10.
This electronic Morse key was found in a Popular Electronics from the 90's. The components are common,...
The circuit presented was obtained in the 1994 Linear Applications Handbook from National...
This circuit is from Radio Electronics from March 1977. The integrated circuit is from that time...