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Project Notes

#294 CD4060 Crystal Oscillator

Exploring the behaviour of the CD4060 ripple counter driven by a crystal oscillator.

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Notes

The CD4060 datasheet describes a crystal oscillator configuration for self-driving the ripple counter. The use of a crystal provides very precise (but fixed) frequency control.

CD4060_crystal_oscillator

See the LEAP#293 CD4060/RCOscillator project a similar circuit that is RC controlled, thus allows variable frequency control.

In this test I’m using a 32.768kHz crystal. The resulting oscillation looks like this (tapped at the net marked CH2 in the schematic):

scope-oscillator

Ripple Counter

The CD4060 is a 14 stage ripple counter constructed of RS flip-flop units - see the functional diagram from the datasheet:

CD4060_functional

The input signal passes 4 stages before the first output is tapped (Q4). Thus the first (Q4) output signal divides the input frequency by a factor of 2^4

Stage 11 (Q11) of the ripple counter is also not exposed on a pin.

The lack of Q0-3 and Q11 is I think just pin economics so it all fits it in a DIP16 package.

The performance is summarised in the following table and the logic analyzer (LA) capture. While 32.768kHz may sound like an odd crystal frequency, the table below gives away its purpose: the ripple counter divides this frequency into lots of familiar powers of 2! Also note how under crystal control, the actual frequency (as measured with an oscilloscope) is exactly equal to the theoretical frequency.

Signal LA Frequency (theory) Frequency (actual) Note
CH2   32768Hz 32768Hz f-input
Q4 07 2048Hz 2048Hz f-input/2^4
Q5 06 1024Hz 1024Hz f-input/2^5
Q6 05 512Hz 512Hz f-input/2^6
Q7 04 256Hz 256Hz f-input/2^7
Q8 03 128Hz 128Hz f-input/2^8
Q9 02 64Hz 64Hz f-input/2^9
Q10 01 32Hz 32Hz f-input/2^10
Q12 00 8Hz 8Hz f-input/2^12
Q13   4Hz 4Hz f-input/2^13
Q14   2Hz 2Hz f-input/2^14

la

Construction

Breadboard

Schematic

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Credits and References

About
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This page is a web-friendly rendering of my project notes shared in the LEAP GitHub repository.

LEAP is just my personal collection of projects. Two main themes have emerged in recent years, sometimes combined:

  • electronics - usually involving an Arduino or other microprocessor in one way or another. Some are full-blown projects, while many are trivial breadboard experiments, intended to learn and explore something interesting
  • scale modelling - I caught the bug after deciding to build a Harrier during covid to demonstrate an electronic jet engine simulation. Let the fun begin..
To be honest, I haven't quite figured out if these two interests belong in the same GitHub repo or not. But for now - they are all here!

Projects are often inspired by things found wild on the net, or ideas from the many great electronics and scale modelling podcasts and YouTube channels. Feel free to borrow liberally, and if you spot any issues do let me know (or send a PR!). See the individual projects for credits where due.