AptPupil:
Speaking of caps... Will 24pf ceramic caps work in place of the 22pf in the ATMega8 (or 168, 328) Arduino circuit with the 16 MHz crystal? No one carries them locally & I have the 24pf's on hand. How much difference will it make. I also have 18pf & 10pf caps. I had thought about putting two 10pf caps in series x2 for the crystal, but that just looks very crowded. I guess, simply put, is there a suitable capacitor alternative for the 22pf caps for the 16 MHz crystal?Thanks,
AptPupil
Sure, 24pf will work. The effect of using padding caps of slightly different values then the crystal manufactures rated capacitance loading spec is that the frequency will be slightly offset from it's nominal marked value. In fact in some crystal oscillator designs one of the fixed padding caps is replaced by a small variable 'trimmer' capacitor so that the nominal frequency can be tweaked while being measured with a frequency counter or other indirect methods. Note that this kind of 'calibration' will not fix frequency error caused from variation in ambient temperatures.
Lefty