Introduction: Accurate 1 Hz Frequency From AC Mains

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Line frequency is, depending on the country 50Hz or 60Hz. This frequency has small fluctuations in the short term, but is compensated daily by the power station resulting in a quite accurate frequency source for many timing applications.

Step 1: Circuit Diagram

Step 2: Circuit Details 1

Step 3: Circuit Details 2

Step 4: Circuit Details 3

Internal diodes protect CD4017B clock input keeping it within supply voltages. Schmitt trigger input allows for slow rise & fall times.

Step 5: Circuit Details 4

Step 6: Breadboard

Step 7: Scope

Step 8: CD4017B Pinout

Absolute maximum voltage for CD4017B is 20V

Step 9: Watch the Video