My apologies. I was naughty and dared to use the ohm symbol on this list a= nd it ended up appearing as "?" question marks! Ack! Tue, 28 Mar 2017, Electron : Of course it is, it's the gate of FETs, not the base of bipolar transis= tors. Theoretically it would be "infinite" impedence, of course it cannot be,= but it's VERY high nonetheless. Of course, there's still capacitance that m= ust not be forgotten. =20 But in the case where the PIC's input pins are being connected to a DIP swi= tch (my application) whose opposite side is Ground, and where there is a la= rge pull-up resistance of 100k-ohm or larger, how much impact does that str= ay capacitance really have? A DIP switch flipped by human fingers is not t= ime sensitive, so I would assume there would be no issues due to that capac= itance. Or am I missing something? Tue, 28 Mar 2017, "Brent Brown" : If all your PIC circuits are bread-board or other "in the lab" type app= lications, then=20 yes they may well work acceptably. But somewhere else like say an indus= trial=20 environment, then yes you are correct - expect noise issues. =20 Let's assume an industrial environment where noise is a concern. More spec= ifically, let's assume a 12-volt automotive electrical system. What are th= e noise implications that should be considered when using large pull-up res= istances when the PIC is running at low voltages (3.0V and under), and wher= e the PIC's inputs are connected to DIP switches that switch to Ground (i.e= .., nothing where timing is critical)? Is there a realistic cap on how larg= e the pull-up should be in light of the said noise? (I assume the noise we= are speaking of here is something that would throw a PIC input pin into an= undesired and unexpected state, correct?) --James W. --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .