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Author Topic: Driving IN-3 bulbs  (Read 3851 times)
Risen
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« on: April 09, 2012, 10:11:20 AM »

I'm fairly experienced with code, but I'm pretty new to the electronics part. When I get my project built I'll contribute some code back here; I'm doing a 6-bulb w/ separators that integrates with an RTC. I've seen this question posted a few times but without a direct answer, so I'm going to try to sum up a few things and see if I can't get this straight.

I'm trying to use some IN-3 bulbs as separators. I believe it's similar to the INS-1; asking for 65-90V, 55V maintaining. Also, I think I'm reading a maintaining amps of 0.8mA?
Datasheet is here, but my Russian isn't very good: http://www.tube-tester.com/sites/nixie/dat_arch/IN-3.pdf

When I pull from the 'test' voltage point, I can get the bulb to light pretty well by putting a resistor in series. I've tried a number of resistor values, in each case the voltage across the bulb was always near 40V. Do these have a variable resistance depending on what voltage you supply? I can calculate the resistor to put the amps across it that I'm looking for. (Landed on 200K to give me about 0.6mA. It glows nicely.) Is that the right way to find the resistor value?

I wired it up to the ArduiNix anodes/cathodes, across a pin I had switching on/off each second. When 'on' the bulb didn't light nearly as fully. When 'off' the bulb still had a small glow. The ArduiNix was multiplexing all four anodes as that's how I intend to run it. I tried changing the multiplex delay but it didn't seem to have much effect on the problem above. It seems it's not getting enough while "on" and yet getting too much when it's supposed to be "off". I'm not sure what to do here.

The ArduiNix seems to be built properly; I have some IN-14 tubes, which light just fine. I've tested all the anode/cathode pairs and they turn on/off as expected. I don't have an expensive enough volt meter to tell you what's happening across them during multiplexing. It reads between 15V and 40V but, again, multiplexing is surely making that inaccurate.

So, basically, the question boils down to this: what's the proper way to drive an IN-3 bulb with the ArduiNix?

Any help is greatly appreciated. Thanks!
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Risen
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« Reply #1 on: April 10, 2013, 11:20:32 AM »

I solved this.

Basically, start by giving up using the ArduiNix by itself. It might work for INS-1s, but not for IN-3s.

My solution was to set one of the ArduiNix anodes always high, giving myself a 170V line-out. I put enough resistance on this line to drive the bulbs appropriately. Then I brought in an output expander, an MCP23008, but using an Arduino with more outputs would be fine too. Hook these outputs up to transistors to control the flow to the bulbs. As far as choosing the right transistor to power it, I looked at the ArduiNix itself to see what it used internally and bought the same exact part.

Hope that helps someone.
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