Seriously? You care enough about temporal accuracy buy an atomic
clock but you don't know how to build one? We won't
tell.Thankfully DIY Physics has a great tutorial on how to build
your own with parts from eBay. The core of the makeshift atomic
clock is an Efratom Model M-100 Rubidium Frequency Standard
oscillator originally designed for use in military
communications and navigation. They can now apparently be found
online in the $150 to $200 price range, and rely on the
radioactive element Rubidium 87 to provide a constant stable 10
MHz signal. But turning it into the source signal for an atomic
clock takes a little more know-how than building the Radio Shack
electronics kits of yesteryear. Keeping it at the perfect
temperature is critical for an accurate signal, and you'll need
to supply 25 volts of DC power to fire it up. So it's not quite
an after school activity, but if you're a technically-inclined
helicopter pilot parent who likes to help—aka do everything—with
your kids schoolwork, this is an A+ scie