IV22 VFD Display

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BobaMosfet
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Joined: Tue Jan 19, 2016 2:48 pm

IV22 VFD Display

Postby BobaMosfet » Thu Jun 29, 2017 5:17 pm

I see people buying IV22 VFD displays on Amazon for $40+, for arduino and so forth-- but why not make one for less? So I did:

Image

The PCBs are 1" x 1.6", and sandwiched. I chose through-hole for experimentation purposes, and could do SMT later, with a single PCB, but I kind of like the industrial look it has as it is. The LM7805 provides 5V for the logic side, the VFD display voltage is of course higher. It's using battery power at the moment but will be using a DC:DC converter powered by a wallwart, soon, as soon as I get the DC:DC converter built. It's designed, but not assembled-- only so many things I can do in a day ;)

The LED is RGB, so I have a rainbow of colors possible,changeable on the fly. I sourced the VFDs from Russia, socket pins from England, everything else from elsewhere around the world out of stock inventory. They can be chained together, I'm making a clock with 6 VFDs (for both time and date), and the DC:DC Boost converter is designed to provide enough voltage and current to support 6. The MCU is an ATMEGA32 @ 16MHz... I like the 40-pin package. Cutting the PCBs down to size, from the larger FR4, and doing the soldering took about an hour to assemble the one you see. I had to translate the IV22 specsheets from Russia, and then used emperical testing to determine actual acceptable currents and voltages. These are circa-1967 displays, triodes actually, and are based on thermionic emission of electrons from the cathode through the grid, to the anode. When you look at the display face on, you are actually looking through the filament (thermionic heater), the grid, and then at the phospher-coated anodes which light when the electrons excite them. The filament is hard to see, and you can see the fine mesh of the grid.

Image

To my knowledge, this is the only other standalone-VFD-single-digit-as-a-device design out there, other than the one being sold on Amazon. By 'standalone' I mean, all the components for backlight and signal control of the VFD are with the VFD as a module, not on the motherboard and the VFD just plugs into the motherboard. This design uses significantly less power, digits will fit side-by-side closer together, and can be plugged into a breadboard for experimentation (or 9-pin header on a motherboard). I also chose a different darlington array, which I believe is safer, and it's designed to use the minimum necessary power for signaling/control.

BM

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Rick_S
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Re: IV22 Display

Postby Rick_S » Fri Jun 30, 2017 3:26 pm

Very nice looking project. How much did it set you back?? You said the ebay ones were about $40, I'm assuming you had a batch of boards made up so the up front for the first one was probably pricey. For the set of 6 you were planning on building are they half price??? Less. VFD's and Nixies are both pretty neat and I really like your compact design. Almost makes them fit up like 7 segment LED displays. I can't wait to see your finished project.

BobaMosfet
Posts: 30
Joined: Tue Jan 19, 2016 2:48 pm

Re: IV22 Display

Postby BobaMosfet » Sat Jul 01, 2017 5:23 pm

Rick,

Thanks. I know I don't post often, intend to post more. Just so busy with work and other stuff, that I don't get as much time to do this as I'd like. The PCBs were the most expensive part-- no surprise there. Each one is $5.08, so $10.16 for each display (just the 2 PCBs). As it is, I put several on one FR4 and then cut them to the 1"x1.6" size. Each display in limited quantity right now is < $15 each to make. In higher volume the PCB cost will drop dramatically. I refuse to pay $40 for a single VFD, when I can design and make my own for less, that consumes less power.

Yes, one of the reasons I wanted them not much wider than the display itself was so they would sit nicely side-by-side. When I get it completed, I'll post some images. I may post a video before then, with more than one, showing the displays in action-- they are really cool. I couldn't justify the expense of true nixies in quantity-- just too expensive, so I went for these (which are circa-1967), and I'm happy with them. I can generate a nice orange glow around them to give them the warm-tube look ;)

BM

BobaMosfet
Posts: 30
Joined: Tue Jan 19, 2016 2:48 pm

Re: IV22 VFD Display

Postby BobaMosfet » Fri Oct 06, 2017 11:40 am

Just a small update. It now runs off of a 9V wallwart, has a boost regulator circuit to support the different voltage level required by portions of the display, an RTC, and of course more than one IV-22 display ;)

Image

The IV-22 digits are removable of course (attached via socket pins), in case one should fail, it's easily changeable. The image above shows displays individually controlled with yellow red, purple and amber colors (although I actually have them changing with each digit each time it changes-- it's currently counting from 0000-9999). The mantissa is actually marching along the bottom. I have been clobbered with a number of things and hadn't gotten the 4th digit done until this morning. In a day or two I'll have the RTC driver completed and then it will be displaying time and date.

I have to make a final decision on physical controls for setting time/date, so I can finish the motherboard schematic and PCB design and get those ordered. It will have battery backup to power the RTC in case the wall-wart is disconnected.

All in all, a very satisfying project.

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Rick_S
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Re: IV22 VFD Display

Postby Rick_S » Fri Oct 06, 2017 4:53 pm

That’s sharp!! The rub led is a nice touch. Great job.

BobaMosfet
Posts: 30
Joined: Tue Jan 19, 2016 2:48 pm

Re: IV22 VFD Display

Postby BobaMosfet » Mon Oct 09, 2017 9:37 am

Rick,

Thanks. Each one has an RGB LED, so color control is based on duty-cycle for each in combination. Colors are even better in person. ;)

BM

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Rick_S
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Re: IV22 VFD Display

Postby Rick_S » Mon Oct 09, 2017 6:00 pm

I just noticed the autocorrect changed rgb in my prior post to rub... LOL


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