Using VFDs as amplifiers


[HP Friedrichs] sent us this cool writeup on how to use scrapped Vacuum Fluorescent Display tubes as amplifiers. For those unfamiliar, a VFD is a display device common to electronics.  Many have been replaced by LCD, but you can still find them in modern products. [Friedrichs] points out that his 2008 ford has a VFD for the multimedia display.

Since these units are basically tubes, he figured that you should be able to use them as a tube amp. After some testing, he found it to be quite adequate.  The project includes tons of background information on how tubes work, how VFDs work and how to utilize it for amplification. In the picture above, you can see him using one (middle) to amplify a home made radio (right).


  1. rasz says:

    why didnt you embed his youtube clip?

  2. adamziegler says:

    Woah… very cool.

  3. gio says:

    great read, thanks.

  4. kljsf says:

    i have also seen these used in ring modulation effects… google it.. just fyi…

  5. JB says:

    “[Friedrichs] points out that his 2008 ford has a VFD for the multimedia display.”
    And people wonder why the US autoindustry is in pain.
    I wouldn’t be surprised if it weighs 3 ton and has a huge umpteen liter gas-gobbling engine too.

  6. noah vawter says:

    the rest of HPFriedrichs’ website is really interesting too! lots of homemade tube experiments.

  7. Clay says:

    Wow, now thats neat. Bravo!

  8. macegr says:

    From his site, he’s got a good YouTube demonstration video you could use for your usual “blah blah blah, after the jump/break/etc”:

  9. strider_mt2k says:

    That’s surprising and surprisingly cool!
    Well done!

  10. pepe says:

    Kainka already did this years ago: (german)

  11. dnny says:

    Here is the ring modulator link:

    ring modulator made from VFD.

  12. Orv says:

    @jb: What’s wrong with a modern car using a VFD? They’re easier to read than LCDs, and provide a more visually pleasing and more washout-resistant display than LEDs. My ’94 Honda had VFDs for the clock and radio display.

  13. andrew says:

    orv: notice you said “my _’94_ honda”

    case in point :)

  14. AnarKIT says:

    VFDs are still relevant devices today. They’re cheap to make and reasonably efficient. You wouldn’t be able to manufacture an LED or lcd display with the same variety of designs and colors as a VFD without increasing the cost and complexity by a significant amount.

    High brightness and readability are key factors in automotive applications. They could have used some other technology but that would have left them in a worse position than they are now.

    Plus when the zombie apocalypse comes, I certainly won’t be complaining about easy to come by amplifier tubes.

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