EEVblog 1601 - How VFD (Vacuum Fluorescent) Displays Work

[EEVblog]

How VFD (Vacuum Fluorescent) Displays Work.



Extracted from a hacking video #717:

[floobydust]

I had a moment rejuvenating a 34401a VFD, connected power to it and it didn't light up. Applied filament power and +30V on the segments, grid floating.
I expected segments to light (normally on unless the grid biased negative) but it stayed dark.
Turns out the "grid" works like a screen grid, not a control grid.

I do the usual filament bake off up to 2x Vfil absolute max, and then also a grid bake off was needed. There is some buildup on it as well.

[Ian.M]

Useful VFD links:
Futaba's VFD Characteristics & Operation guide AN-E-1103A http://www.vwlowen.co.uk/arduino/vfd/VFD-Application-Note.pdf
Noritake's A Guide to Fundamental VFD Operation
https://www.noritake-elec.com/technology/general-technical-information/vfd-operation

[ksio89]

I had a Sony MHC-DX7 shelf stereo/mini system that bought in 2000 or 2001, was the display a VFD or just an LCD one?

[floobydust]

VFD's are superiour for readability in sunlight and low temp (below -30°C) I used them a lot in industrial panels that are located outdoors. Instead of low temp fluid and heaters in LCD's.
Noritake iTron/Futaba were kings making the best VFD's but LCD's took over and had the lower power consumption, you don't need a few watts for the filaments.

Interesting the Korg Nutube 6P1 (by Noritake) is just a VFD as a low voltage twin triode. They're just exploiting the non-linearities I think THD 1-20% very fuzzy and perhaps corny.

Sony MHC-DX7 uses a VFD https://elektrotanya.com/sony_mhc-dx7.pdf/download.html#dl

[thm_w]

I had a Sony MHC-DX7 shelf stereo/mini system that bought in 2000 or 2001, was the display a VFD or just an LCD one?

The manual calls it "fluorescent indicator tube" so its some form of VFD.

[Ranayna]

May i ask what led you to extracting this part from an old video?
Not that i mind really, it was a bit of a "blast from the past" And i remembered many points from the original video.

Is it just to make this aspect easier to search for and find this video?