Tuesday, June 17, 2014

6-stage CD4013 clock divider

So, following on from my last post demonstrating an Arduino-based clock divider, I made another one with just dual-flipflop (CD4013) logic chips. This design divides into powers of two, from /1 to /32, using six flipflop units. Nothing fancy or ground-breaking - just implementing something I found on Wikipedia.

It seems that it needs the input clock pulse voltage to be reasonably close to the IC supply voltage. When I ran it at 12V supply with 5V input pulses it didn't seem to work very well at all. 6V supply with 5V pulses seems to work quite reliably. This can be improved by feeding the input clock line with a MOSFET.

Essentially this is an implementation of the cascading arrangement depicted here. The only parts not noted in that diagram are:

  • The additional flipflops, which are wired in exactly the same way
  • RESET and SET lines on each CD4013 must be tied low
  • The usual power supply rails

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