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Modify "ICE TUBE" for other VFD's?
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Modify "ICE TUBE" for other VFD's?

by ReZnoR on Fri Oct 24, 2014 8:48 pm

Recently finished putting the ICE TUBE kit together... and since I have a few other VFD's laying around here I wonder if it's possible to use them instead of IV-18?

Maybe I just need to modify the CODE?

The VFD's in question are IV-11's and IV-12's. I was looking at the datasheets and I can't see much difference between them.

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Re: Modify "ICE TUBE" for other VFD's?

by jarchie on Fri Oct 24, 2014 10:27 pm

The VFDs you mention do differ in the filament voltage as well as the grid/segment voltage. You would need to adjust the filament driver circuit accordingly. Adjustment to the boost voltage might be feasible in the code alone, but you'd probably want to use a Zener doide with the appropriate breakdown voltage.

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Re: Modify "ICE TUBE" for other VFD's?

by ReZnoR on Sun Oct 26, 2014 1:12 pm

Ok the difference between IV-11 & IV-12 is small... but compared to IV-18 it's bigger.

In the specs for IV-18 it says "5V and 75-95mA" for the filament. And the filaments could be supplied from a separate circuit... it doesn't have to go via the driver... right?

Here with ice tube they made it so it could be turned off for power saving. I was gonna use 6 tubes... and that means 6 times the current in parallell and the driver can't handle that much current. But could it work in series?

Maybe I've got it waaay wrong?

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Re: Modify "ICE TUBE" for other VFD's?

by phild13 on Sun Oct 26, 2014 4:34 pm

In the specs for IV-18 it says "5V and 75-95mA" for the filament. And the filaments could be supplied from a separate circuit... it doesn't have to go via the driver... right?
The icetube clock filament is powered by VCC (5 volts) and comes through Q3 which is a simple switch turned on/off by the processor. The VFD driver has no control over the filament.
Depending upon how much current you will need you can either swap out Q3 for something able to handle the increased current while being mindful the pc board traces are small and won't handle much current, or.use Q3 to turn on/off a larger "power board" which is a much better option.
.
I was gonna use 6 tubes... and that means 6 times the current in parallell and the driver can't handle that much current. But could it work in series?
Short answer.. NO. Keep the tubes filaments in parallel.

Study the Max chips (VFD Driver) spec sheet for how to drive the tubes grids/segments properly using the VFD chip..
http://datasheets.maximintegrated.com/e ... AX6931.pdf

The tubes use different grid/segment voltages than the tube in the icetube clock so you will need to rework the voltage supplied by the boost voltage circuit in order to drive the grids/segments in the tubes properly.

Taking a look at the design pages of the icetube clock will help. https://learn.adafruit.com/ice-tube-clock-kit/design

I would take a look at this page
http://www.candrian.gr/index.php/iv-11- ... al-design/
There is some very good information on there about using Nixie tubes with an icetube type circuit design and a Max VFD driver..

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Re: Modify "ICE TUBE" for other VFD's?

by jarchie on Sun Oct 26, 2014 6:01 pm

If you replace F1 with a larger fuse, and find a good replacement for Q3, you might be able to connect the filaments of three tubes in series, providing ~1.5v across each filament. Two more sets of three wired in parallel to the first would give all nine digits used by the clock. Unfortunately, I suspect that wiring in series would result in noticeable brightness differences among the tubes, so Phil is probably right to recommend against this.

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Re: Modify "ICE TUBE" for other VFD's?

by jarchie on Mon Oct 27, 2014 2:08 pm

PhilD13 wrote:The tubes use different grid/segment voltages than the tube in the icetube clock so you will need to rework the voltage supplied by the boost voltage circuit in order to drive the grids/segments in the tubes properly.

I was thinking this also, but I was going off a secondary source which recommended a voltage of 25v (30v maximum). I'm uploading some more authoritative documentation which is, unfortunately, in Russian. But if I understand correctly, the maximum grid/segment voltage is 70v when multiplexing--the same as for the IV-18. I'm looking at the parameters under the section "Импульсное режим" (literal translation: "pulse mode"). So I now think that it might be possible to use the Ice Tube Clock boost circuit as-is to provide the necessary grid/segment voltage.

And more good news: If the boost voltage is that high, then the tubes would exhibit more consistent brightness when the filaments are wired in a three-tube series, as described in the previous post!

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Re: Modify "ICE TUBE" for other VFD's?

by phild13 on Mon Oct 27, 2014 2:36 pm

I see no real reason why one can't use the icetube clock as a basis for a Nixie tube design. Probably be pretty cool with Johns firmware. Here is my take on things.

English IV-11 spec sheet
http://www.tube-tester.com/sites/nixie/ ... V-11_2.pdf

Looking at the spec sheet for a IV-11 tube it appears each tube filament will draw a maximum of 110mA. Six tubes will give 660mA. I don't know if the pc board traces going to/from Q3 can handle that much current at least without excessive voltage drop so I would consider some options.

Since the Nixie tubes will need a pc board anyway (Nixie board) designed for them to mount on, I would consider making a few (minimal) modifications to the icetube board to enable stacking a Nixie board on top of the icetube board.

I would remove the power connector from the icetube board and re-purpose the connector holes for input power from the Nixie board. The 9v power would now come in to the Nixie board first.

I would get a straight male connector tp plug into the icetube boards tube socket in place of the durrent tube board 90 connector. This will transfer the necessary signals up to the Nixie board and support one end of it. Get a couple matching length pc pin post connectors and install them in the icetube board where the 9volt connector was. This supplies 9v power back to the icetube board from the Nixie board and also supports that end of the Nixie board. An alternative is to use a standoff of appropriate length at the tab of the icetube boards regulator (or a long screw with nuts instead of a standoff) and use wire to make the power connections between boards where the power connector was.

The filament connection on the connector (pin 1 icetube connector) will allow the use of Q3 as the enable signal for a Dc/Dc switching buck regulator that is mounted on the Nixie board such as this one:http://www.digikey.com/product-detail/en/AOZ1280CI/785-1277-1-ND/2769845 (Yea, I know it is surface mount, but it is easy to solder by hand. ) Set the Buck regulator to the 1.5 volts needed and run the tubes filaments in parallel.

By running tubes in parallel, if one were to burn out then that one only goes out making troubleshooting easier where in series all are out so which one caused the issue? You can run the tubes with series filaments directly from the 9 volts supply 9/6=1.5v and it will probably work ok like John says with the existing boost voltage. You will still need an appropriate FET or transistor to control the filament power. It can still be driven off of the existing Q3. If using a transistor then R3 becomes the base resistor (change to appropriate value if necessary) for the larger transistor. Personally, I would opt for the buck regulator option. I think that is better overall from a design standpoint.

The 9v power brick will need to be larger (1.5 - 2A) to accommodate the increase in current. A larger PTC fuse sized at about 1.5A (750mA hold) would probably be plenty or you can just not use a fuse as the buck regulator has built in protections and the icetube main board is still protected by the original fuse.

On the nixie board you would place the power connector, a larger PTC fuse (if used) and the Buck regulators required support components.

This configuration would enable one to keep the functionality of the icetube firmware, and hardware with only (removing the power connector) minimal changes.

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Please be positive and constructive with your questions and comments.