IV-15 / DM-160 -- Wire-up help needed

[HikariFaith]

So I have a bunch of IV-15 / DM-160 VFD tubes I got a few months back (I have a mix of both) and have been wanting to experiment with them a bit. The problem is they're not as straightforward as the nixies I've been working with, so I don't understand how to identify the individual wires/pins on them, nor have the datasheets been helpful in knowing how to turn them on or what voltage they need to turn on. Can I please get an explanation of how to wire up these tubes? I really want to see how they look in person.

[Tristan]

Fortunately they aren't much more complicated to drive. The DM-160 includes sample circuits and seems to be available here:

https://frank.pocnet.net/sheets/009/d/DM160.pdf

It needs 1V across the filament, +50V or so on the anode (referenced to the filament as it's a directly heated cathode.) and 0V connected to the grid via a 100K resistor. Note that the datasheet shows that the filament is driven with an AC voltage. This avoids having a DC voltage gradient across the filament relative to the grid and anode that would possibly cause it to light unevenly. It should work with DC and the filmanent should have been laid suitably (I.e. a single filament going up and back down the tube) such that it does light fairly evenly but you will need to consider that one end of the cathode will have a different voltage relative to the grid and this will affect the grid cutoff voltage. 

To just make it glow you can hook up -f to 0V and +f to 1V. The average voltage of the cathode is then 0.5V so you could hook the g to 1V via a 1 Megohm resistor (based on the example in fig.2 which shows how the grid can be slightly positive biased as long as the current is appropriately limited). Then hook the anode a to +50V.

[Martin Niec]

I can confirm, that it works according to Tristan's suggested schematic :)

http://electrosurplus.online.fr/DM160/Kit%20DM160%20Oscillator%20V1.pdf this might also be helpful for identifying pins on the tube.

[Moses]

I would recommend Mr. EEVblogs video on how VFDs work.. https://www.youtube.com/watch?v=gZIRPJt69sM

10 minutes well spent if you are curious how they work.

-Moses

[Terry Kennedy]

As this was already answered, I'll just reply with a bit of historical trivia - the DM160/6977 displays were used as logic level indicators in early electronic computers. I don't know if that was also the intended use for the IV-15. When mixing and matching, be aware that the IV-15 are generally a little shorter and fatter than the DM160/6977 ones. The base glass seal color can also vary.

[HikariFaith]

Yup. I have some of both. So long as they work the same I’m fine with that.

On Jan 30, 2025, at 10:22 PM, Terry Kennedy <terry-...@glaver.org> wrote:

As this was already answered, I'll just reply with a bit of historical trivia - the DM160/6977 displays were used as logic level indicators in early electronic computers. I don't know if that was also the intended use for the IV-15. When mixing and matching, be aware that the IV-15 are generally a little shorter and fatter than the DM160/6977 ones. The base glass seal color can also vary.

On Thursday, January 4, 2024 at 4:02:04 PM UTC-5 HikariFaith wrote:

So I have a bunch of IV-15 / DM-160 VFD tubes I got a few months back (I have a mix of both) and have been wanting to experiment with them a bit. The problem is they're not as straightforward as the nixies I've been working with, so I don't understand how to identify the individual wires/pins on them, nor have the datasheets been helpful in knowing how to turn them on or what voltage they need to turn on. Can I please get an explanation of how to wire up these tubes? I really want to see how they look in person.

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