Accurate 1 Hz Frequency From AC Mains

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