One second with Accuracy (CB1536E )

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Published: Thursday, 26 March 2020 13:40

Written by Newton C. Braga

 
    This circuit was found in a 1977 Radio Shack documentation. Its purpose is to generate 1 Hz signals from the 60 Hz power grid. The 7490 divides the frequency of the network so as to obtain 3 Hz by synchronizing the 555 which causes the LED to flash at accurate intervals of 1 second.