RC filter with LED

I am designing a shield for an arduino project. I am going to have a long run , about 30 meters or so. So I have been doing some reading on RC filters and clipping diodes. I have read about this circuit below and believe this will create a ruggard digital input filter. This signal is only a switch so speed is not a problem. My question is… Is this a good location for my indicator LED? I’m not sure if it will interfere with the mechanics of the filter. I can’t see any reason why it would but I’m no expert.

I wanted to add about 9 of these inputs and include the filters. Also how can I calculate the Shottkey diodes size? Also i’ve read there will be a slight ‘bounce’ in the voltage as the filter works so it will get a backward voltage of about -0.6V is this a problem on an Arduino?

Thank you for any help.

filter with led.JPG

Overkill, use 10k / 10nF / 10k perhaps. Having a series resistor on the pin means you don't need clipping diodes, and the other R and C form the low-pass filter to kill noise and interference. Use shielded cable for that length, that's the most important step to take.

Clipping diodes make sense with higher voltages to limit the current into the chip's protection diodes. Any small signal schottky will work for clipping.