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Split-flap passenger information displays produced by Czechoslovak company Pragotron, were in the past very popular in Czech, Poland and other easter-block countries.
In this movie, i try to show the basic principle how a single split-flap pragotron display module works, how it knows when to stop spinning, and how the control singnalling looks like, and how such a simple perforated metal drum witch brushes and diodes makes genuine "brain" of such device.