Posts Tagged “74xx”
A recent PetitFoo talk at the Chaospott on how to debounce keys with a Schmitt trigger prompted me to play with a 74HC14 IC I had lying around.
A Schmitt-trigger converts an analog voltage to a digital logic level. It has two voltage thresholds, and the interesting thing happens between the two:
- Below the lower threshold the input is considered logically low, so the inverter outputs a logic high.
- Above the upper threshold the input is considered logically high, so the inverter outputs a logic low.
- Between the two thresholds the Schmitt-trigger keeps the input state, so the output doesn't change.
Here is an oscilloscope screenshot of the basic behavior of one inverter of the 74HC14, using a triangle wave from the function generator as the input: More ...