> I've got one running unattended > 5 months now that's < 1 second ahead of NBS internet time. 1s/5months -> 76E-9. Adding an always-on body-heat oven aka worn wristwatch can help achieve similar results with std wristwatches and a little fiddling.. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .