Sometimes it seems like eBay is the world’s junk bin, and we mean that in the best possible way. The variety of parts available for a pittance boggles the mind sometimes, especially when the parts were once ordered in massive quantities but have since gone obsolete. The urge to order parts like these in bulk can be overwhelming, and sooner or later, you’ll find yourself with a fistful of old stuff but no idea how to put it to use.
Case in point: the box of Russian surplus seven-segment vacuum fluorescent displays (VFDs) that [w_k_fay] had to figure out how to use. The result is a tutorial on quick and dirty VFD drivers that looks pretty handy. [w_k_fay] takes pains to point out that these are practical tips for putting surplus VFDs to work, as opposed to engineered solutions. He starts with tips on characterizing your surplus tubes in case you don’t have a pinout. A 1.5 V battery will suffice for the hot cathode, while a 9 V battery will turn on the segments. The VFDs can be treated much like a common cathode LED display, and a simple circuit driving the tube with a 4026 decade counter can be seen below. He also covers the challenges of driving VFDs from microcontrollers, and promises a full build of a frequency counter wherein the mysteries of multiplexing will be addressed.
Sounds like it’s time to stock up on those surplus VFDs and put them to work. For inspiration, take a look at this minimalist VFD clock, or perhaps mix VFDs with Nixies to satisfy your urge for all things glowy.
Hmm, I always assumed that the ‘VFD’s like that were just a 7seg LED in a glass envelope…
I thought the same thing, except I was originally expecting an article about variable frequency drives, not those old glass tubes with a fairly basic led displays.
Acronyms will be the downfall of the modern world, just you watch.
If you can find them, Itron made a serial VFD that’s really easy to use. I have some demo code and a video on my website.
https://ethanmye.rs/projects/vfd/
Similarly, Noritake (who I think merged with itron) also make/made HD44780-compatible displays. I have a really nice 40×2 that runs off a single 5V supply.
I used to have a lot of fun driving old VFDs from VCRs and such as a kid.
With those large VFDs it’s important to use an AC waveform or pulse on the filament to get an even display brightness, especially if you are driving them from a fairly low (12V) source.
Started reading to find out about these cheap surplus variable frequency drives and was massively disappointed when it was something about some 7 segment displays…
I share your VFD interest.
Glow On!
http://incredulist.blogspot.com/2017/09/vfd-dg10fi.html