BTW, d'you think I can stack a pair of .22uf caps, giving .44uf rather than the .47uf cap, and it will work ok? Kinda have the .22's in stock.
Same with the 470ohm resistors...I have some 270's in stock that ought to work ok. as LED dropping resistors.
How come u use 39pf for the Crystal caps....most of the 12Mhz crystals are around 18pf, which require 30pf caps.
Crystal Capacitor Formula (Parallel Mode)
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Let: CL = Crystal's load capacitance
CP = Circuit's parasitic capacitance
CI = Chip's input capacitance
C1 = Crystal oscillator capacitor 1
C2 = Crystal oscillator capacitor 2
Then: C1 = C2 = 2 * CL - (CP + CI)
Example: For a crystal with 18pF load capacitance (CL)
and assuming CP + CI = 5pF (typical), we have
C1 = C2 = 2 * 18 pF - 5pF = 31pF. We can then
use two 30 pF capacitors (closest standard
value).