[Dino] celebrates the 131st anniversary of the Photophone


[Dino Segovis] wrote in to share yet another installment of his Hack a Week series, though this one is quite timely.

It was 131 years ago today that [Alexander Graham Bell] unveiled the Photophone to the world. A precursor to fiber optic technology, [Bell’s] incredibly important invention can be easily replicated in your garage, as [Dino] shows us.

The original Photophone was constructed using a megaphone and crystalline selenium cells at the focal point of the receiver, however this version can be made with easy to obtain parts. [Dino] rigged his laptop up to a speaker on which he mounted a mirror, before setting it out in the sun. The vibrations of the mirror modulate the sunlight, reflecting it onto a solar cell positioned at the end of a long, black PVC tube. The solar cell’s leads are fed into an amplifier followed by a speaker, which broadcasts the audio.

The demonstration goes off without a hitch, and while some might be underwhelmed by the technolgy, imagine how incredible it would have looked 131 years ago!


  1. jamieriddles says:

    Who knew solar cells could respond that fast…

  2. zool says:

    pretty cool

  3. Brad says:

    What an outstanding hack. Can’t wait to do this with my kids.

  4. addidis says:

    The seriously amazing part is this is from 130 years ago…

  5. Charlie says:

    Underwhelmed?! It still never ceases to amaze me just how amazing some of this stuff is. We live in the future.

  6. I remember first learning about this technique from the outstanding Forrest Mims guides a good 15 or more years ago. Very nice.

  7. Ugly American says:

    Bell tried to get glass fiber put up instead of wires but people thought the old man had snapped.

  8. gmcurrie says:


    What always gets me is the ‘nominative determinism’ of Alexeander Graham Bell:


  9. pff says:

    He didn’t invent the Bell
    I know lots of people with the surname Bell and none of them invented anything Bell related
    Maybe its just a coincidence?
    yep thought so get over it

  10. gmcurrie says:

    @pff – “I know lots of lots of people with the surname Bell and none of them invented anything Bell related”…

    Are you wearing a lab-coat and occasionally consulting notes on a clipboard whilst speaking in a flat Germanic monotone?

  11. twopartepoxy says:

    Graham Bell was way way way way way ahead of his time, I wonder what he would be inventing if he was alive today?

  12. pff says:

    I don’t think i understand your comment
    was it a lampoon?

  13. david says:

    Skype for Android (but with video)

  14. gmcurrie says:

    Well, you diss me, I kick back! – Simples : )

    (My riposte was an allusion to the film cliche of the Logic-Driven Nazi Scientist who knows everything except humanity, kindness & humour – Yep – a bit extreme – din really mean it at all – jus kidding – all the best to you now!)

  15. Morbious Stone says:

    Dude using this principal and a laser can i use it for beaming internet?

  16. anti-fanboi says:

    Champion effort!


  17. kabukicho2001 said, says:

    ir-diodes can do the same thing

  18. Hitek146 says:
  19. Morbious Stone says:

    Hey thanks Hitek146 so awesome!!

  20. Whatnot says:

    For a more direct read:


    = Google patent search for ‘photophone’ and ‘bell’

    (I find it more reliable and informative to actually see a patent rather than hear someone who heard someone tell about it.)

  21. Dino says:

    A search results page is more direct? :)

  22. Whatnot says:

    @Dino Yes, it shows relevant patent but there are a bunch of those and with various dates and on various aspects of the concept, so a single link to a single patent would not do.
    And besides, it’s google that provides the patent reading interface so it’s google anyway if I did a direct link to a specific one.

  23. Tech B. says:

    “He didn’t invent the Bell
    I know lots of people with the surname Bell and none of them invented anything Bell related
    Maybe its just a coincidence?
    yep thought so get over it”

    Last names usually indicate the family profession. His family most likely at some point made bells for a living, not that they invented them.

  24. Munch says:

    Folks, I hate to break it to you, but LASERS DO NOT WORK WELL for open-air optical communications. The atmosphere suffers badly from centimeter-sized convection currents which decoheres the light, leading to a crap-ton of fading and poor quality communications.

    High-powered LEDs work much, much, much, much, MUCH, MUCH, MUCH better.

    See http://www.modulatedlight.org/optical_comms/optical_index.html

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