"The 74HC14; 74HCT14 is a hex inverter with Schmitt-trigger inputs. This device features
reduced input threshold levels to allow interfacing to TTL logic levels. Inputs also include
clamp diodes, this enables the use of current limiting resistors to interface inputs to
voltages in excess of VCC. Schmitt trigger inputs transform slowly changing input signals
into sharply defined jitter-free output signals."