איבר דולר אמריקאי מראש spark gap radio schematic פיטורים בכוונה כוכב לכת
Spark-gap transmitter - Wikipedia
How does the width of the gap between two conductors, in the method that uses DC spark in the gap to get radio waves, relate to the frequency of the waves? -
Sparks
How to build the simplest radio transmitter - the spark gap radio - YouTube
Spark Transmitters
DIY Spark-Gap Radio Transmitter and Explanation — Steemit