
In 1950 the first carbide and water devices were introduced. The
ignition was by flint, instrument control was mechanical and the shot
interval was regulated by water volume, i.e controlled through the
resulting produced gas volume. Later acetylene and propane gas was used,
while the flint was, in course of time, replaced by a more reliable
high-voltage `piezo´ ignition.


It was noted that the regular single-shot did not allow for reliable
protection of crops over a sustained period. A mechanical control system
was developed in which two shots in quick succession was given. This
development improved the effectiveness of the equipment but was
expensive and prone to malfunction.

1988 saw the introduction of electronically controlled sonic blast shock
devices. This was a giant leap towards the effective long-term defense
of crops, bringing reliability and greater application.
