Questions regarding IV-17 or IV-14 vfd tubes.

[Chaos Hydra]

As the topic says, what do you guys do for the 1.5v for the anode voltage. an AA battery? I was thinking to use two bias resistor and get it from my 5VDC logic circuit input. Are there any better options to do this?

Also, just double check my Russian, Pin 1 goes to 1.5V and pin 11 goes to ground, right? pin2(for IV-17) goes to 25V and the rest pins are 25V soucing inputs.

Thanks in advance!

[petehand]

Heater voltage, I think you mean. How many are you running? Connect one heater pin (1 or 11) of each tube to 5V through a 47 ohm resistor, then the other pin of all of them together to ground through one resistor, of 20 ohms divided by the number of tubes. So for 4 tubes, use a resistor of 20/4 or 5 ohms - 4.7 ohms is ok. This raises the cathode enough above ground that the tubes blank properly, and having them all on the same resistor makes them all at the same potential. Check by powering up the heaters in a dark room. If you can see the heaters glowing even very dull red in total darkness, they're too hot, increase the common resistor until you can't see them.

I don't know why you would connect pin 2 to 25V. Maybe you mean pin 12, the grid. Connect it to 25V for permanently on, or switch it for multiplexing.

[Kejian Lin]

Thanks for your reply! Yeah I mean pin 12 to 25 VDC, mis-type.

So for the first part. I will have 8 tubes. So I put 47 ohm in series with pin 1 to 5 v and all 8 pin 11s together and through a 20 ohm. Well, everything gets better when my dmm gets here.

The method of testing you said is great! I will keep it in mind.

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Cheers

Kejian Lin "Robert"

[petehand]

Not quite. The pin 11s go to a (20 divided by 8) ohm resistor, like 2 point 7 ohms. Yellow Violet Gold.

[Instrument Resources of America]

""Yellow violet gold""  ??????  Try again.  Ira

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[Chaos Hydra]

I see what you mean now. Still, I managed to find a regulator chip that can do the trick, because it take 5V input.
http://www.linear.com/product/LT1587-1.5
Thanks a lot!

[Kejian Lin]

So, for MAX 6931 chip, is it static drive mode or pulse drive mode? My understanding is static and the Vbb need to be 30 V.

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[Terry Kennedy]

On Wednesday, July 22, 2015 at 2:12:43 PM UTC-4, Chaos Hydra wrote:

I see what you mean now. Still, I managed to find a regulator chip that can do the trick, because it take 5V input.
http://www.linear.com/product/LT1587-1.5
Thanks a lot!

If possible, you want to use AC filament drive. DC will generate a brightness gradient depending on the voltage at that end of the filament compared to the other voltages. This is particularly noticeable on large displays like the ILC1-1/7.

[petehand]

Beg pardon. I had originally written 4.7 ohms, changed one instance, not the other.

[Chaos Hydra]

Well, as a newb, I do not how to do AC filament drive so I settled for DC. Since I will use tube play later on, Would you mind show me some good resourse explain how to do it? Ｉ appreciate any help!

[Bill van Dijk]

Have a look at the attached link to Noritake:

 

https://www.noritake-elec.com/display/vfd_operation.html

 

Bill

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[petehand]

With single character tubes like the IV17 you don't need to drive them with AC. The filament runs up and back parallel so there's negligible gradient in the electric field and no discernible brightness gradient in the tube, and AC drive is just time and effort wasted for nothing. You will, however, find that individual tubes vary in brightness by a huge amount, even from the same batch.

[Terry Kennedy]

On Thursday, July 23, 2015 at 10:38:26 AM UTC-4, Chaos Hydra wrote:

Well, as a newb, I do not how to do AC filament drive so I settled for DC. Since I will use tube play later on, Would you mind show me some good resourse explain how to do it? Ｉ appreciate any help!

There used to be nice single-chip solutions for this, like the TI LM9022 (now obsolete, and the wrong output voltage for the IV-4 or -17). As Pete mentioned, you don't need to do this for small tubes like these. But if you wanted to experiment with other tubes it becomes more important. The linked Noritake document in a previous reply has a good overview of the reasons they always recommend AC drive.

There is enough variation in the IV series displays that the normal methods of dealing with a higher-than-desired filament voltage - multiple tubes in series, tubes in parallel with single dropping resistor - may not result in acceptably uniform brightness in a "commercial" product. Even the hobbyist "IV-17 Smartsocket" board used per-tube filament resistors so the relative brightness could be adjusted.

[Per Jensen]

On 24 Jul 2015, at 12:01, Terry Kennedy <terry+go...@tmk.com> wrote:

There used to be nice single-chip solutions for this, like the TI LM9022 (now obsolete, and the wrong output voltage for the IV-4 or -17). As Pete mentioned, you don't need to do this for small tubes like these. But if you wanted to experiment with other tubes it becomes more important. The linked Noritake document in a previous reply has a good overview of the reasons they always recommend AC drive.

The LM9022 was just a remarked LM4871 (which is in production) http://e2e.ti.com/support/power_management/isolated_controllers/f/188/p/289255/1009125

// Per.

[Chaos Hydra]

I do have LM9022, they are still manufactured in authorized or unauthorized factories in China. But anyway, I am planning on use MAX 6921/6931, but I don't think they have filament drive on them.

[Chaos Hydra]

If that unavoidable, then I will settle with DC filament bias. however, I may also have IVLM-1/7 in the system too, do they need AC filament bias?

[Quixotic Nixotic]

On 24 Jul 2015, at 14:51, Chaos Hydra wrote:

> I do have LM9022, they are still manufactured in authorized or unauthorized factories in China. But anyway, I am planning on use MAX 6921/6931, but I don't think they have filament drive on them.

Didn't someone find that the LM9022 was an out of spec something else, rebranded or something? Someone looked at the die and it was the same.

I was getting them as official samples long after people on neonixie said they were obsolete, but that was some years ago now.

John S

[Nick]

That would be in thread https://groups.google.com/d/msg/neonixie-l/HevOjKD3oqQ/vGweitu5eIQJ 

Bottom line: Microphotographs on LM9022 dies show that the die is actually etched as a LM4871 - the die is thus the same and it's just the external labelling that changes...

Nice bit of work by John Taylor...

Nick

[Sean Hill]

I’ve had good results using the Microchip TC4425 (MOSFET driver) and driving its inputs with a 10khz square wave to create a crude filament inverter.

http://ww1.microchip.com/downloads/en/DeviceDoc/21421E.pdf

Its advantage over the LM9022 being that it’s easy to get :)

On Fri, Jul 24, 2015 at 7:16 AM, Nick <ni...@desmith.net> wrote:

That would be in thread https://groups.google.com/d/msg/neonixie-l/HevOjKD3oqQ/vGweitu5eIQJ 

Nice bit of work by John Taylor...

Nick

On Friday, 24 July 2015 15:12:30 UTC+1, Nixcited delighted wrote:

On 24 Jul 2015, at 14:51, Chaos Hydra wrote:

> I do have LM9022, they are still manufactured in authorized or unauthorized factories in China. But anyway, I am planning on use MAX 6921/6931, but I don't think they have filament drive on them.

Didn't someone find that the LM9022 was an out of spec something else, rebranded or something? Someone looked at the die and it was the same.

I was getting them as official samples long after people on neonixie said they were obsolete, but that was some years ago now.

John S

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[petehand]

I use AC drive for multicharacter displays, where there's a definite gradient from end to end. I use the Si9986 H bridge. It works over the range 3.5V to 13.5V with TTL level inputs over the whole range.