EEVblog #423 – HP5061A Atomic Clock Cesium Beam Frequency Standard

A look at one of the original HP 5061A Cesium Beam atomic clock frequency standards used in the “flying clocks” experiment in the 1960’s, that showed (not definitely at the time) that time dilation as part of Einstein’s relatively theory was correct. The effect was not confirmed until a more precise run in 1971, again with the same clocks.

Forum Topic HERE

About EEVblog

Check Also

EEVblog #1334 – Mystery Dumpster Teardown

Mystery dumpster teardown time! With the most amazing mechanical mains power switch you’ll ever see! ...


  1. A portable piece of history !

  2. What? No teardown?

  3. Hi,
    It’s really nice episode!
    A couple of years ago I was participating in modern HP5071A caesium beam tube replacement. It was also interresting to observe clock dying process while caesium atoms amount was too small so every clock regulation circuit was saturated and standard’s frequency started do drift away from other reference exponentially 🙂

  4. Good video. More episodes like this one.

  5. Dave, I please make more of theese short episodes, they are easier to watch over a fast meal. 🙂

  6. Hi Dave, I think you will be interested in the content of this pdf.
    “ ” , (HP journal 1964 on the flying clock)
    Correlating Time from Europe to Asia
    with Flying Clocks from HP journal 1965

    Thanks for all your interesting eevblog episodes.
    best regards

    (from Paris ,France)

  7. Is it only me that the more I think about time the more conceptual it looks for me… Some philosophical questions occur such like what is time, what is now and similar…

Leave a Reply

Your email address will not be published. Required fields are marked *