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Project Notes

#656 Crystal-Locked Schmitt Oscillator

Testing a basic crystal-locked Schmitt oscillator using a 74HC14.



I tested the basic SchmittOscillator a very long time ago in LEAP#022. I was prompted to try the crystal-locked variation after seeing CD40106 aka 74C14 covered in IMSAI Guy’s chip of the day:


Circuit Design

the slowest crystal I have to hand is 4MHz, so I needed to add 20pF stabilization capacitors to maintain oscilation. The second inverter buffers the output and the 51kΩ feedback resistor ensure’s the oscillator is kicked into action.




Test Results

4.00019MHz according to my scope:


Credits and References

About LEAP#656 CMOS/TTLOscillators
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LEAP is just my personal collection of projects, 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 (IMHO!).

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