CMOS Frequency Divider

CMOS frequency divider Back to basics with this one. Frequency divider (or clock divider) with flipflop IC.

This super simple circuit will divide the input frequency F by 2. CD4013 has two flipflops, so if you wire those in series you get divide-by-4. And then third one would be divide-by-8 and so on.

My first example is quick and dirty 1970s style 200kHz oscillator (with huge vacuum tube style crystal). Please note the hi-tech screen shot from telequipment D61a. And also note how much better/cleaner square wave I got from the divider. Second picture is practical example to upgrade my BK-Precision 1820 frequency counters internal reference.

4000-series CMOS ICs will work up to 20Vdd and about 20MHz. For higher frequencies 74HC74 would be suitable. That is 5Vdd and it's good up to 30MHz. There most certainly are other things to concider, but let's stay in basics.

Tube crystal oscillator BK precision frequency counter

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