Hacking A 30-year-old Russian VFD

March 3, 2018 by Rich Hawkes 8 Comments

Reddit user [InThePartsBin] found some VFDs (Vacuum Fluorescent Displays) on an old PCB on eBay. The Russian boards date from 1987 and have a bunch of through-hole resistors, transistors and a some mystery ICs, plastic wraps around the legs and the top of the tube is held steady by a rubber grommet (the tip itself goes through a hole in a board mounted perpendicular to the main board.) Being the curious kind of person we like, and seeing the boards weren’t too expensive, he bought some in order to play around with to see if he could bring them back to life.

After getting the VFDs lighting up and figuring out the circuitry on the back, [InThePartsBin] decided that a clock was the best thing to build out of it. It was decided that a specialized VFD driver chip was the easiest way to make the thing work, so a MAX6934 was ordered. To give the clock some brains, an ATmega328 was recruited and to keep time, [InThePartsBin] had some DS3231 real-time clock modules left over from a previous project, so they were recruited as well. A daughterboard was designed to sit on the back of the vintage board and hold the ‘328 and the VFD driver chip.

Once [InThePartsBin] soldered on the components it was time to fire it up and send 1’s to the driver to turn on all the segments on all the tubes. Success! The only thing that [InThePartsBin] has left to do is write the code for the clock, but all the segments and tubes are controllable now, so the hardware part is done. There are other VFD clock projects on the site: Check out this one, or this one, and bask in the beautiful steel-blue glow.

Via Reddit.

Quick And Dirty Driver Tips For Surplus VFDs

January 21, 2018 by Dan Maloney 8 Comments

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.

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Now Is The Golden Age Of Artisanal, Non-Traditional Tube Amps

September 24, 2016 by Mike Szczys 17 Comments

Earlier in the month, [Elliot Williams] quipped that it had been far too long since we saw a VFD-based amplifier build. Well, that dry spell is over. This week, [kodera2t] started showing off his design for a VFD headphone amp.

Here’s the thing, this isn’t using old surplus vacuum fluorescent displays. This is actually a new part. We first covered it about 18 months ago when Korg and Noritake announced the NuTube. It’s the VFD form factor you would find in old stereo and lab equipment, but housed in the familiar glass case is a triode specifically designed for that purpose.

Check out [kodera2t’s] video below where he walks through the schematic for his amplifier. Since making that video he has populated the boards and taken it for a spin — no video of that yet but we’re going to keep a watchful eye for a follow-up. Since these parts can be reliably sourced he’s even planning to sell it in his Tindie store. If you want to play around with this new tube that’s a pretty easy way to get the tube and support hardware all in one shot. This is not a hack, it’s being used for exactly what Korg and Noritake designed it to do, but we hope to see a few of these kits hacked for specific tastes in amp design. If you do that (or any other VFD hacking) we want to hear about it!

And now for the litany of non-traditional VFD amps we’ve grown to love. There is the Nixie amp where [Elliot] made the quip I mentioned above, here’s an old radio VFD amp project, in this one a VCR was the donor, and this from wayback that gives a great background on how this all works.

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VFD Clock Only Speaks Romanian

August 24, 2016 by Al Williams 9 Comments

There’s no shortage of clock projects, but [niq_ro] has his own take using a vacuum fluorescent display (VFD), and Arduino, and a pair of MAX6921 ICs. Those chips are made to drive a VFD, and the use of two of the ICs required a bit of work. The Arduino is not a great time keeper, so the clock also uses a DS3231 clock module and a humidity and temperature sensor.

The clock is in Romanian, although there are some options for different text. You can find the code on GitHub and can see the result in the video below.

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Reverse Engineer A VFD After Exploring How They Work

March 4, 2015 by Mike Szczys 21 Comments

[Dave Jones] got his hands on a really wide, 2-row Vacuum Fluorescent Display. We’ve come across these units in old equipment before and you can get them from the usual sources, both new and used, but you need to know how to drive them. This recent installment of the EEVblog reverse engineers this VFD.

The function of these displays is pretty easy to understand, and [Dave] covers that early in the video after the break. There is a cathode wire and phosphorescent coated anodes. When current is applied the anodes glow. To add control of which anodes are glowing a mesh grid is placed between the anodes and the cathode wire. Applying negative potential to the grid prevents the electrons from traveling to the anode so that area will not be lit.

Now driving this low-level stuff is not easy, but rest assured that most VFDs you find are going to have a driver attached to them. The reverse engineering is to figure out the protocol used to control that driver. On this board there is a 2-pin connector with a big electrolytic filtering cap which is a dead giveaway for power rails. Looking at the on-board processor which connects directly he ascertains that the input will be 5V regulated since this is what that chip will expect. Connecting his bench supply yields a blinking cursor! [Dave] goes on to pump parallel data and test out the control pins all using an Arduino. He finds success, sharing many great reverse engineering tips along the way.

We often call this type of thing a dark art, but that’s really just because there aren’t a lot of people who feel totally comfortable giving it a try. We think that needs to change, so follow this example and also go look at [Ben Heckendorn’s] recent LCD reverse engineering, then grab some equipment and give it a try for yourself. We want to hear about your accomplishments!

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The ChronodeVFD Wristwatch

October 26, 2014 by Marsh 47 Comments

Not just another steampunk fashion statement, [Johngineer’s] ChronodeVFD wristwatch is as intricate as it is beautiful. Sure, we’ve seen our share of VFD builds (and if you want a crash course in vacuum fluorescent displays, check out Fran’s video from earlier this year) but we seldom see them as portable timepieces, much less ones this striking.

The ChronodeVFD uses a IVL2-7/5 display tube, which in addition to being small and low-current is also flat rather than rounded, and features a transparent backing. [Johngineer] made a custom board based around an AtMega88 and a Maxim DS3231 RTC (real time clock): the latter he admits is a bit expensive, but no one complains about left-overs that simplify your design.

The VFD runs off a Maxim MAX6920 12-bit shift register and is powered by a single alkaline AA battery. A rechargable NiMH would have been preferable, but the lower nominal voltage meant lower efficiency for his boost converters and less current for the VFD. [Johngineer] won’t get much more than 6-10 hours of life, but ultimately the ChronodeVFD is a costume piece not meant for daily wear. Swing by his blog for a number of high-res photos and further details on how he built the brass tubing “roll cage” enclosure as well as the mounts for the leather strap.

Never Miss A Thing With This Programmable Vacuum Fluorescent Display Ticker

May 24, 2014 by Rick Osgood 9 Comments

VFD Ticker

[Coyt] wanted a more convenient way to keep up to date with the ever-changing Bitcoin exchange rates, as well as weather and other useful information. He realized that the vacuum fluorescent display (VFD) he had purchased a couple of years ago would be perfect to display small amounts of information.

[Coyt] discovered that the VFD had a serial interface. The problem was that the VFD was looking for a 12V serial signal but the Raspberry Pi he wanted to use runs at a 3.3V. Upon closer inspection [Coyt] discovered that the VFD actually ran at lower levels as well, but it had a level converter chip installed in front of the main connector. He simply bypassed the level converter and was then able to get the RasPi speaking directly to the VFD.

The brain running this display is a Raspberry Pi. The Pi runs a Python script that pulls down all of the relevant information from the internet and displays it on the VFD. [Coyt] didn’t stop there, though. He knew that having the screen on all of the time would be somewhat of a waste, so he hooked up a PIR sensor to automatically turn on the display only when needed. The PIR sensor can detect motion in the room and will disable the display after a set period of inactivity. Most of this is powered by an LM7805 voltage regulator. While [Coyt] admits a linear regulator is not his ideal solution, it does get the job done. The metal stand acts as a nice heat sink for the regulator.

[Coyt] also wanted his project to have a certain aesthetic. He started by bending a metal plate into a stand for the electronics. He then mounted the VFD on the front of the stand and the RasPi on the back. He also mounted green LEDs between the two plates to light up the edges for a little extra pizzazz. [Coyt] believes he can use the RasPi to PWM the LEDs but this has not yet been implemented. This would allow him to pulse the light for added effect.

Since the whole thing is run by a Python script, it would be trivial to modify it to display other kinds of information. What would you do if you had a motion sensitive automatic ticker?