[sdiy] Cheap frequency counter for oscillator calibration

[Barry Klein]

Anyone ever tried using one of the iphone/touch piano tuning apps?
I have 2 (Petersons and Cleartune) that I have used to tune my piano and 
they both work fine for this...
If not just what you want, they could probably create a special GUI just
for this purpose if enough ask for it.  The Cleartune programmer did a 1st 
gen
touch version just for me so I could utilize a plugin microphone module. (it 
worked by default
in the Petersons version).

Barry