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Isolated 1-Hz Clock(CD4017 )

2016-02-21 05:39  
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This article briefly describes Isolated 1-Hz Clock (CD4017). This principle is easy to understand, but also very practical. Depth understanding of circuit elements, you can better grasp this principle. In this circuit, you can learn about and purchase these components: CD4017.

One of the author’s physics projects required an accurate 1-Hz (seconds) clock signal. Unfortunately, precision 10-MHz quartz crystals are expensive, while another problem was found in the inability of most common or garden 40xxCMOSlogic chips to work at such a high frequency. However, a typicalCMOScounter like the 4017 has such a high input resistance that its clock input has ‘radio’ properties. The effect is exploited here to convert the stray magnetic field picked up from a mains transformer into a clock signal. Here, the signal is induced in a short piece of wire (approx. 5 cm) connected to the clock input of a CD4017 decade counter for division by 10.


Figure 1 

The resulting 5-Hz signal is then divided by 5 by a second 4017 (IC2) to give an output of 1 Hz.LEDD1 ?ashes to indicate the presence of a sufficiently strong magnetic field. The pickup wire should be placed close to the mains transformer, without compromising electrical safety. Always use the greatest distance at which a clock signal is reliably generated. For 1-Hz output from 60-Hz power systems, use output 6 of IC2 (pin 5).



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