Rare Nimo Tubes

[Paul Parry]

Just spotted these on the Bay

http://www.ebay.co.uk/itm/IEE-nimo-6000-31-0000-10-Electron-Gun-Display-Tube-CRT-Nixie-Rare-/282121267238?hash=item41afbce826:g:B70AAOSwIgNXoSa~

Nothing to do with me, don't know seller etc.. but know they are interesting and unusual tubes..

[Dekatron42]

A set of six just sold from the same seller: http://www.ebay.co.uk/itm/IEE-nimo-6000-31-0000-10-Electron-Gun-Display-Tube-CRT-Nixie-LOT-OF-6-NOS-RARE-/282111471567?hash=item41af276fcf:g:5eUAAOSwIgNXlN-c

/Martin

[Nick]

USD 100 each seems to be about the going rate.

The ones I have are in the same bulk packing...

Nick

[gregebert]

Anyone here have a NIMO clock they built ? I'm curious about their  observed lifetime; datasheet says 10,000 hours which is slightly more than 1 year if running 24/7. 

[Dylan Distasio]

I took the bait and picked up 4 of these to add to my future projects pile.  That said, I've never experimented with voltages beyond the dekatron range.  I don't know that I'm interested at this point in building my own kV PSU (although I would be eventually).  Can anyone recommend a relatively inexpensive off the shelf PSU to drive these with?  According to the datasheet, I should be looking for 2.5kV on the anode, with 1.1V on the filament.  I'm not sure exactly how to drive the grid.  Does the grid consist of the cathodes?  Apologies, but I have zero CRT experience at this point, and any pointers would be appreciated.  I'd like to at least be able to test these when they come in.

Thanks!

On Thu, Aug 4, 2016 at 10:05 AM, gregebert <greg...@hotmail.com> wrote:

Anyone here have a NIMO clock they built ? I'm curious about their  observed lifetime; datasheet says 10,000 hours which is slightly more than 1 year if running 24/7. 

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[Dekatron42]

You can use Photo Multiplier Tube (PMT) power supplies, buying them from Ebay is usually cheaper than in a shop.

There was a clock called Cyclock that used the similar Telefunken XM1000 (if I remember correctly) that you might be able to Google to find the details.

/Martin

[gregebert]

Attaching the datasheet.

Basically, each numeral is controlled by a grid, so 10 grids A numeral that is off is driven to -6V; drive to +4V to turn on. The datasheet shows a center-tapped transformer for the filament and I suggest you do the same.The filament is also the cathode, so any voltage on it with respect to the grid(s) will affect the brightness. Grounding the center-tap effectively cancels-out the effect. I would also soft-start the filament to prolong the tube's life.

I could not find any pictures of 4-digit NIMO clocks on the web, so enjoy your project and be the first.

Please don't use a microwave oven transformer to generate the HV because they are extremely dangerous; I'd use a diode-capacitor voltage multiplier instead.

[John Rehwinkel]

> I took the bait and picked up 4 of these to add to my future projects pile. That said, I've never experimented with voltages beyond the dekatron range. I don't know that I'm interested at this point in building my own kV PSU (although I would be eventually). Can anyone recommend a relatively inexpensive off the shelf PSU to drive these with?

I like using a CCFL supply with a voltage doubler. Since only a tiny amount of current is required, you can also get away with a lower voltage supply (like a Tayloredge) and quite a few stages of multiplication.
Another cheap and common source is those handheld electric flyswatters (which will give around 2kV from a pair of AA cells). Negative ion generators are cheaply available as surplus, and can also furnish several kilovolts easily. Copiers and laser printers can be a source (their corona wires use high voltage), or ozone generators, CRT and plasma TVs, and electrostatic dust precipitators.

> According to the datasheet, I should be looking for 2.5kV on the anode, with 1.1V on the filament. I'm not sure exactly how to drive the grid.

There are ten grids, one for each digit. You can actually drive them directly with CMOS logic, if the filament voltage is appropriate, they only take a few volts. You drive one a few volts positive (relative to the cathode) to light that digit, and drive the rest of them a few volts negative (also relative to the cathode: in CRTs, all voltages are measured relative to the cathode). A common lashup is like in the data sheet, where pulldown resistors keep the grids held low, and transistors are used to pull one positive at a time to light the digit wanted.

> Does the grid consist of the cathodes?

The filament is actually the cathode. The grids are the apertures for each digit. You can drive the filament using an ordinary transformer, with dropping resistors or capacitors calculated to deliver the rated amount of power. You can even drive it directly from a pair of 5V inverters operated out of phase, along with appropriate dropping resistors or capacitors. In this instance, capacitors are preferred, so you can bias the filament to the DC voltage you want to make the grids voltages easy to work with. If you're working with 10V CMOS, and bias the filament to +6V, you can simply ground the grids that are off, and connect the one you want to turn on to +10V. This will give the grids the -6V/+4V swing (relative to the cathode) that they're supposed to see.

> Apologies, but I have zero CRT experience at this point, and any pointers would be appreciated. I'd like to at least be able to test these when they come in.

The easiest test is a continuity test to make sure the filament isn't broken. However, I'm guessing you want to see one lit. Go find one of those electric flyswatters for the anode voltage (they're a few dollars), and be careful, you don't want to touch high voltage, and have your reflex throw your tube across the room!

- John

[Instrument Resources of America]

On 8/7/2016 9:25 AM, John Rehwinkel wrote:
>> I took the bait and picked up 4 of these to add to my future projects pile. That said, I've never experimented with voltages beyond the dekatron range. I don't know that I'm interested at this point in building my own kV PSU (although I would be eventually). Can anyone recommend a relatively inexpensive off the shelf PSU to drive these with?
> I like using a CCFL supply with a voltage doubler. Since only a tiny amount of current is required, you can also get away with a lower voltage supply (like a Tayloredge) and quite a few stages of multiplication.
> Another cheap and common source is those handheld electric flyswatters (which will give around 2kV from a pair of AA cells). Negative ion generators are cheaply available as surplus, and can also furnish several kilovolts easily. Copiers and laser printers can be a source (their corona wires use high voltage), or ozone generators, CRT and plasma TVs, and electrostatic dust precipitators.

You missed electronic bug zappers, the kind that you hang up with the
U.V. fluorescent lamp in them. Ira

[John Rehwinkel]

You missed electronic bug zappers, the kind that you hang up with the U.V. fluorescent lamp in them.  Ira

I did actually think of them (there's actually an outfit that sells zapper transformers as neon power supplies), but they're rather more dangerous, so I intentionally omitted them.

- John

[A.J. Franzman]

Careful, I'm fairly sure the IEE nimo tubes have two filaments in parallel, each serving a bank of five electron guns (a.k.a. grids). You might have one side open but still see "continuity". I don't recall whether the XM1000 tubes have the same type of arrangement.

[Nick]

Little more on these - I had a few broken ones in the bulk packing, so here are some internal shots showing the digit mask and a couple of the electron guns (one under each digit in the mask).

Nick

[Dylan Distasio]

Does anyone have experience undervolting these to 2kV?  I see on the datasheet that this moves it significantly down the brightness curve, but am wondering how noticeable it is in practice.

I was thinking of picking up an Emco F20 PS which while not as cheap as I'd like seems like an easy way to get 2kV for a noob.  The next model up is 3kV and I would rather not overvolt as I'm concerned it will shorten the tube life (not sure if that is actually true if current stays the same though). 

Thanks,
Dylan

On Aug 8, 2016 12:01 PM, "Nick" <ni...@desmith.net> wrote:

Little more on these - I had a few broken ones in the bulk packing, so here are some internal shots showing the digit mask and one of the electron guns (one under each digit in the mask).

Nick

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[gregebert]

My vote is to play it safe and find or make a supply that gives you 2.5kV.

I was going to recommend a series dropping resistor, along with the 3kV supply, but I dont think that is a good idea. The reason is that while the resistor will provide a voltage drop at nominal current,  it wont do anything at low or zero current. Given NIMO tubes are expensive and rare, I wouldn't risk applying higher-than-spec voltages, just in case it might do something unexpected. For example, I've seen tin whiskers develop in laptop CCFL driver boards. Literally a microscopic metal hair that grows in a high electric field. Even at lower voltages, I've seen evidence suggesting this happened in my IN-1 nixies.

High voltage zener diodes (~160V) might work but be very careful about leakage current; you may end up with the same paranoia I have about using resistors mentioned above. If you do use zeners, I would use a 'bleeder' resistor from NIMO-anode to GND to drain zener leakage current, such as a few 22Meg in-series.

[Dylan Distasio]

Hi John-

I ended up grabbing one of these cheap fly swatters to test with.  Any idea of the current these put out?

Thanks,
Dylan

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[John Rehwinkel]

I ended up grabbing one of these cheap fly swatters to test with.  Any idea of the current these put out?

I would have guessed a few milliamps, but I decided to actually go try it myself.  I hooked one to an ammeter and got a whopping 130mA out of it.  No wonder the insects sizzle!  Since there are capacitors involved, the peak current can be more.

- John