In the previous log I documented a modern imitation of the old VFD display look. There is no shortage of the original VFD displays on ebay though. A word of warning: their quality may be highly variable. Out of 3 that I bought only one worked without issues.

A while ago I designed a PCB that would let me use this display in a project as a module. I pretty much copied a design for a Futaba VCR display that I found on Taobao. It is based on MT3608 step up converter for -24V, AC generator around some 74LS04 and UCC27517 gate driver + some discretes and the main course is PT6315, which is a very convenient and rather flexible VFD display driver.

Here's the kicanvas link to the module schematic and PCB. It works.

https://kicanvas.org/?github=https%3A%2F%2Fgithub.com%2Fsvofski%2Fcalculator-maybe%2Ftree%2Fmaster%2Fvfd%2Fvfdmodule

There's not much to say other than compared to the more recent Japanese VFDs this display looks rather dim. I'm not sure if this is simply because the technology is inferior, their age, or maybe my driving circuit is inadequate. It's good, just less bright than expected.

I always keep going about how unique the shapes of these segments are. They are very unusual and for some people simply iconic. Generic modern LED 7-segs in comparison are lacking the character, they are just 7 slabs and a dot put together in the most unimaginative way possible.


The inner structure of these displays is a sight to behold.

And the obligatory HELLORLD:

The module must be powered by 5V. The limiting factor is UCC27517 gate driver used in the AC generation, which has undervoltage cutoff around 4.3V. I've yet to test if this module can be driven by 3V3 TTL signals, but I'm hopeful.

Update: I recorded a longer video about it: