Atomic Clock

just a small "on a whim" eBay purchase - a rubidium clock which was (literately) sawn off an old mobile phone tower.
not really much in the way of electronics all I built were power supplies really but I think it's a cool little project and I use it to sync my midi/digital equipment - not that you need an atomic clock to do that but it cost £40 and all those weird audiophiles will love it.

on the datasheet for this thing, it had a note saying that it's locked into it's super-accurateness when the output goes low on the indicator output. so I made a little transistor switch to light an LED when it goes low

edit: whilst looking up some info on RF I came across this site which has some brilliant information on how to adapt your own version of this very atomic standard Rubidium Standard

Technical Manual