Ninety years ago this month, the January 1926 issue of Science and Invention carried these diagrams for a simple one-tube regenerative receiver.  The circuit was shown in response to a question from a reader, one James Moore of Chicago, who asked for a circuit which could be built with a fixed coupler, variable condenser, variometer, and tube, all presumably parts he had on hand. The editors came up with this circuit, which uses the variometer to control regeneration. The circuit was said to be quite selective.

The same column also carried the following question and answer from one Felix Grandich of New York, who wanted to know whether you needed a ground wire to communicate with other planets, and if so, why. It turns out you did.

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