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 telecommunications publication of 1978. Its purpose is to obtain...
This setting appears with variations at various points on this site. This is from a Motorola...
This circuit is from a 1967 documentation. The circuit uses germanium transistors and has an...