The Blitzrad or Neeff wheel is an electromechanical arrangement that interrupts an electrical circuit at periodic intervals. The visible sparks generated at the point of interruption were used to detect the electrical voltage (a voltaic column ). It was first presented in 1838 by the Frankfurt doctor Christian Ernst Neeff .
The arrangement consists of a gear and a resilient sliding contact . The latter scans the gear wheel on the outer circuit, whereby the circuit is briefly interrupted after passing through a tooth roof and thus a spark is generated when current flows. The gear can be driven by a hand crank. The switching frequency can be freely selected by means of the speed of the gearwheel and, due to the number of teeth, is relatively high.
This clear technical solution has long been considered obsolete. To influence ( modulate ) signals, gears have also been used in the optical field ( speed of light , frequency dependence of optical sensors ).
The lack of separation of the mechanical control from the electrical contact with the Blitzrad was achieved for gasoline engines with the breaker in which friction components were lubricated and tempered contacts were used. In a two-stroke engine with several ignition coils , the interrupter had only one tooth (cam), but an adjustable contact for each cylinder (time and duration or contact distance).
- Lightning wheel . In: Heinrich August Pierer , Julius Löbe (Hrsg.): Universal Lexicon of the Present and the Past . 4th edition. tape 2 . Altenburg 1857, p. 895 ( zeno.org ).
- Lightning Wheel . In: Brockhaus' Kleines Konversations-Lexikon . Verlag FA Brockhaus, Leipzig, 1910