Maximum length a resistor ladder can go on analog pin?

Question

If i'm using all 220 Ω resistors and i'm using the Arduino's analog I/O, how far can I go? Is 14 resistors feasible?

Robert Peter Oakes · Accepted Answer

yes that looks like it should work, one key at a time of course. There may be some allowable combinations if you can calculate the actual voltages but it would be easier to go a different approach if thats what you wanted

anyway, should work a treat, let us know how it goes

Peter

Robert Peter Oakes · Answer

depends on how your connecting them and what your connecting to the junctions

basically you can connect 100 in series if you wanted to, you end up with 22000 (22K) resistance with even drop of say 5V across them all but if you load a junction with less than say 200K (10* as a rough order of magnitude of the chain resistance) then you will significantly change the voltage seen on that junction. Think resistors in parallel

Hope this answers your question, if not then draw a sample picture of what your trying to do and well give a better answer

Robert Peter Oakes · Answer

well there is nothing stopping you electrically but I dont see from that how you will know which key is pressed

I am assuming your planning on using an alalog input to determine the key, you will get the same value of voltage no matter the key