I was reading a tutorial on debouncing the outputs of a rotary-encoder which are read by a micro-controller. Below is the circuit given:
The writer of the tutorial claims the following:
"In the above circuit we use a 1uF capacitor with an SN7414 Schmitt-trigger input NAND gates that clean up the switch-contact noise."
I have couple of questions regarding this claim and the circuit.
1-) I can understand the reason for the use of capacitors, they act as RC low pass filters and can filter bounces. But how does the SN7414 Schmitt-trigger help debouncing here? Is that really needed or does it improve debouncing?
2-) In the above circuit the resistor and the capacitor forms a low-pass filter with a cut-off freq. fc. What is the motivation/idea when it comes to sizing the capacitor here. Why 1uF? I mean let's say we have a rotary-encoder and it is recommended to be used with 10k resistors. Which parameter of the encoder from its data-sheet should be taken into account when sizing the capacitor. Is there a method or reasoning between choosing the capacitance and a parameter in the data-sheet?