SOLVED!First: apologies if this is in the wrong category, there are just too many to choose from that this question may fit in...
I am building a midi controller and got everything working perfectly on the breadboard with the duemilanove, the 16 pots (being read through two 4051's) were stable at any position, fluctuating within 3 points (my smoothing value). I switched the duemilanove out for a breadboard arduino I made a few months ago and I tried powering it with (many different) wall warts (6.5v/200ma, 9v/150ma, 9v/800ma, 12v/1A). No matter what I used, I could not get the pots to hold their values any more... they would fluctuate by upwards of 15-20 points and therefore are pretty much useless...
After much searching, I figured out that the adc is fairly sensitive to changes in the reference voltage, so I began testing the voltages with various options I have available and noticed that the 7805 in the bb arduino was outputting about 4.95v steady. I switched it out with an LM2940 and it locked onto 4.99v and was steady... Using the bb arduino, but the duemilanove (atmega removed) for power (5v and gnd hooked up) I get 5.07v (and the pots are stable).
I guess my question would be: is the adc really THAT sensitive, in that .08v can cause an almost 10 fold increase in the jitter of the values?
What can I do to solve the problem?
I know you will want me to post a schematic, but I don't have one yet, and since everything works perfectly using the duemilenova on its on, AND when only using the power it provides (but using the bb arduino for everything else), I cannot see an issue with that part... I have a feeling my lack of basic electronics knowledge is hurting me here...
Thanks everyone!