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Project Notes

#234 CMOSInverterOscillator

Use a CD4096 to generate an oscillating waveform and plot the results



I found this oscillator circuit as part of the LEAP#182 PowerSupply317Kit.

It is another variation of the basic Schmitt Inverter Waveform Generator pattern, which I tested in LEAP#022 SchmittOscillator.


… is quite terrible actually. Oscillation is only sustained for a small sweep of the 100kΩ pot. The waveform is also heavily asymmetric - with a duty cycle at most 25%.

Setting C1 R1 (pin 2-3) Frequency
max sustained oscillation 10µF 2.5kΩ 27Hz
min sustained oscillation 10µF 40kΩ 0.4Hz
max sustained oscillation 1µF 2.15kΩ 165Hz
min sustained oscillation 1µF 40kΩ 4Hz

Scope trace for C1=1µF, R1(2-3)=2.15kΩ:


Scope trace for C1=1µF, R1(2-3)=40kΩ:




The Schematic


Credits and References

Project Source on GitHub Project Gallery Return to the LEAP Catalog

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.