Found in documentation from the 1990s, this circuit supports equivalent transistors. The range is on the order of a few tens of meters.
This circuit was found in a Popular Electronics from the 90's. The circuit can be used to convert...
This circuit works with only 1.5 V and can be powered by a solar panel. The circuit is from 1991....
In fact, the original American publication exaggerated a little about the range that a good...