VFD as a sound amplifier

[Alessandro Lambardi] had some vacuum flourescent displays that he pulled from junked VCRs. His latest project is an experiment to use one of the VFDs as a headphone amplifier. This means he’s trying to use them as vacuum triode amplifiers, aka vacuum tubes. He did get it to work but as he suspected, the output is fairly low power. It may be possible to use this setup as a preamp and build an actual tube amp to use along with it.

Update: Thanks to [Fallen] for mentioning that we’ve covered this concept in the past.

[Thanks Muris]

Comments [13]

tagged: amp, vacuum fluorescent display, vacuum tube, vfd

13 Responses to VFD as a sound amplifier

Fallen says:

April 22, 2010 at 8:15 am

I swear I read this on here before…

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Ryan says:

April 22, 2010 at 8:34 am

Yeah HAD posted something like this before. Still, more info on something like this is always good I wonder if you could use several of these to get a somewhat decent output? Also, I have to wonder if they actually sound any good :/

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therian says:

April 22, 2010 at 9:08 am

no real use in this trick since both valves and VFD are disappearing equally

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John Scherer says:

April 22, 2010 at 9:15 am

This is cool. Yes is more than likely not very practical but still cool none the less. This is the kind of stuff I wish I could think of. Way outside the box.. I like to hack shit as much as anybody and some actually work on occasion, however most of my attempts are well within the preverbal box. This is hacking in its purest form. Makes me want to go read the book “Hackers” by Steven Levy.

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osgeld says:

April 22, 2010 at 9:40 am

@therian

VFD’s may be going the way of tubes, but you can still walk into any thrift store and pick up a truck load of old vcr’s which contain the devices

vintage radios and amp’s maybe not so much

but yea with such a low output its functionality is reduced to “hey, thats cool”

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jh says:

April 22, 2010 at 9:42 am

my brand new kenwood faceplate had a VFD display. I wouldn’t say that VFD are disappearing, just being used in different areas than before.

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Dielectric says:

April 22, 2010 at 10:25 am

Heh, from the RSS headline I thought he’d be using a Variable-Frequency Drive to generate sound via some big motor, not unlike those hard-drive noisemakers. This is cool too, though. I think they used VFD displays in car radios too, so any pick-n-pull could be a good source of parts.

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bothersaidpooh says:

April 22, 2010 at 10:51 am

i looked into this a while ago.
seems that they can indeed be used to build a very low power full bridge VFDTC which should work from 24v and up.

the only problem is that they aren’t designed to handle much power due to the fluorescent paint acting as a dielectric barrier.
you might be able to “toast” that by applying high voltage between the grid and cathode to fragment the coating a bit…
DANGER HIGH VOLTAGE

as for sources of interesting looking displays, have a dig around for IN-80 8 digit Russian VFDs on greedbay as they can run with very low voltages and currents.

interestingly an amplifier with phase shift can become an oscillator so you could if you wanted make a 4 output sinewave oscillator with no semiconductors at all (!)

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mrgoogfan says:

April 22, 2010 at 11:50 am

that is neat, but mini tubes are still readily available.

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Doug says:

April 22, 2010 at 12:51 pm

Huh, I have the exact same VFD display…

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NatureTM says:

April 22, 2010 at 4:34 pm

I hope it’s easier to implement then using as a display. I bought a VFD for a buck at a surplus store thinking the low price would offset the difficulty of use. It’s sitting in a box right now. I think the only reason I’d ever use it is for the accomplishment of doing it, otherwise I’ll stick with serial LCD so I can concentrate on the actual project.

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jim says:

April 23, 2010 at 7:33 am

Why not use a VFD preamp and a digital amp? Power with valve sound, and opposite ends of the engineering spectrum.

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Jon says:

May 20, 2010 at 2:44 pm

@therian

Don’t know how you can say VFD’s are going away, since they are still being mass produced for vehicles and appliances to this day.

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