Sixty years ago this month, the July 1959 issue of Electronics World carried the plans for this carrier-current transmitter. The set was billed as a “wireless neighborhood baby sitter.” Parents in the author’s neighborhood needed something to participate in bridge sessions and “kaffe klatches” while the baby napped at home. To avoid stringing wires from house to house, he put together this carrier current transmitter. It would cover all houses on the same transformer and could be heard on the host’s standard AM radio. To keep it legal, the author recommended checking to make sure that the signal didn’t go further than about 50 feet from the power lines. If the signal was too strong, then a smaller value for C19 should be used.

And when the kids got older, he suggested that it could be turned into a neighborhood broadcast station by adding a phono input in addition to the mike.