This circuit for light modulated in frequency (FM) operating at 50 kHz was found in a 90’s Electronics Now. The circuit has an active filter. Modern equivalent transistors can be used.
Two identical transformers can be used as a single improvised isolation transformer. The maximum...
This transmitter can send its signals from several kilometers away, depending only on the antenna...
This circuit was found in Radio Electronics magazine from January 1959. The power transistor must...