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STROBOSCOPE WITH VISUAL SPEED INDICATING SYSTEM EMPLOYING LIGHTS

  • US 3,781,656 A
  • Filed: 05/21/1973
  • Issued: 12/25/1973
  • Est. Priority Date: 05/21/1973
  • Status: Expired due to Term
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First Claim
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1. In combination with a timing light for timing an engine, said timing light including a housing and a flash tube, a system for visually indicating whether the engine being timed is operating at a predetermined speed or above or below said predetermined speed, said system comprising means responsive to the speed of the engine being timed for providing a first signal having a frequency that varies in response to the speed of the engine being timed, means for providing a variable reference signal which, when added to said first signal, provides a third signal having a predetermined DC value when the engine being timed is operating at said predetermined speed and DC values above and below said predetermined DC value when the engine being timed is operating above and below said predetermined speed, means connecting said means providing said first signal and said means providing said reference signal for adding said first signal and said reference signal, at least first, second, third, fourth and fifth devices each having a NAND gate function and each having an input terminal and an output terminal and an open and closed state, each of first to fifth devices being closed when the signal applied to said input terminal thereof is of a first polarity and greater than a predetermined magnitude and being open when the signal applied to said input terminal of said first polarity and less than said predetermined magnitude, means for applying said third signal to said input terminals of said first and fourth devices when said third signal is of said first polarity, means for inverting the polarity of said third signal to provide a fourth signal having the same DC value as said third signal but opposite polarity, means for applying said fourth signal to said input terminals of said second and fifth devices when said fourth signal is of said first polarity, means connecting said input terminal of said third device to said output terminals of said first and second devices, first, second and third engine speed indicating lights, means connecting said first light in a first circuit including said output terminal of said third device, said first circuit having current flowing therethrough sufficient to illuminate said first light when said third device is closed, said first light being unilluminated when said third device is open, means connecting said second light in a second circuit including said output terminal of said fourth device, said second circuit having current flowing therethrough sufficient to illuminate said second light when said fourth device is closed, said second light being unilluminated when said fourth device is open, and means connecting said third light in a third circuit including said output terminal of said fifth device, said third circuit having current flowing therethrough sufficient to illuminate said third light when said fifth device is closed, said third light being unilluminated when said fifth device is open, said lights being associated with said housing and readily visible to a user of said timing light.

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