This circuit is intended for underwater communications. Of course, the critical point is the shielding to avoid water. The circuit is from an Electronic Hobbysts Handbook from the 90s.
This circuit was found in a 1964 Electronic Design. The components are of the time, and modern...
This circuit was found in a 1999 publication. Its purpose is to flash two LEDs according to the...
This circuit is from a Popular Electronics from the 90's. The circuit directly drives high power...