My Conn Stroboconn electronic tuner uses an adjustable tuning fork, and
I allow 4 hour warm-up before use.  I calibrate it against WWV standard
radio broadcast (440 Hz) and have never experienced any drift.  Resolu-
tion is about 1 cent, perhaps even less.  Motor speed of the 12 strobe
wheels might drift, but I have never noticed it.

It's fun to watch while feeding in music from CDs, especially singers.
Confirms my suspicions about some singers.  They must drive Andy crazy!

John Spradley