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.
Using transistors at the time, this circuit was found in a 1970s documentation. Transistors support...
This circuit was found in a Signetics documentation from the 1980s. The integrated is a PLL and...
We published this circuit in a magazine of the 90s, but it is still present by the components it...