This PCB debounces four pushbuttons using a passive low-pass RC filter and Schmitt-trigger inverter. Each pushbutton outputs an active-HIGH signal. There are four pushbuttons on the board.
This PCB uses a 220 ohm pull-up resistor, pushbutton, and low-pass RC filter (1 kohm resistor and 10 ufarad capacitor: tau = 0.01 seconds) to debounce the pushbutton. The output of the low-pass filter is connected to the 7414 Schmitt-trigger inverter to generate an active-HIGH pushbutton output.
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