Spark Transmitter
From ETHW
The Spark Transmitter
The origins of wireless telegraphy and radio hinged around the use of spark transmitters. These transmitters were used in the VLF and LF frequency bands. One characteristic of the spark tramitter was its ability to produce a lot of unwanted interference (in todays crowded bands where spectrum efficiency is important), With the advent of the vacuum tube, spark transmitters have been relegated to history.
