OT: Nixie Tubes

"DoN. Nichols" wrote:


The MPSA-42 is a high voltage driver transistor made by what used to be Motorola. It probably ended up at "ON Semiconductors", but they were widely used, and should be available surplus.
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    Thanks!
    Enjoy,         DoN.
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On Tue, 19 Sep 2006 01:21:30 GMT, the renowned "Michael A. Terrell"

I don't have a datasheet handy for the original 7441A, but the 2nd generation 74141 has outputs leakage rated at 55VDC. It blanks for invalid codes for leading-zero blanking etc.

Yes, they're mature cheap multiple-sourced 300V NPN transistors. About a dime new (Fairchild brand) if you buy a whopping $8 worth.
Whether you want to use 7441s or transistors plus, say, CMOS 4017's really depends on your design aims. The ancient TTL parts draw quite a bit of supply current.
Best regards, Spehro Pefhany
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Spehro Pefhany wrote:

Not to mention that a lot of the original TTL chips have been discontinued, and you may be buying a 20 year old part.
A lot of early TTL chips had crappy plating on the pins, and corroded while in storage, or in some types of sockets. I've had to wire brush and re-tin thousands of them with acid flux, when I had a decent solder pot. Brush, flux, dip, clean, repeat. Whole days of cleaning up bad pins, and replacing cheap sockets.
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While the 74xx devices are getting rare, there are a lof of other variations of the device number are commonly available. Try the 74HCT (TTL output levels) or 74HC (CMOS output levels) instead. The TTL devices have a bunch of different variations as shown by the letters after the 74 reference number and you mix and match them as long as you take into consideration the drive requirements input and output of each family of the devices. Anybody still sticking to the original design is missing out on the higher speeds and lower current draws of many of the newer variations available.
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    [ ... ]

    You also want a diode in series, or you will also light up the Anode -- which is usually a grid.
    Some of the variants of Nixies have two alternative Anodes, which select from two groups of digits. This somewhat simplified the decoding in the early days before there were custom ICs for the purpose. IIRC, these were called "Bi-Quinary".
    Enjoy,         DoN.
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On Mon, 18 Sep 2006 01:52:40 GMT, "Tom Gardner"

They are just special neon lamps. They take something over a hundred volts to fire (light) and then the voltage drops back to around 90 volts.
One precaution. They will draw as much current as they can - to the point of destruction. Apply the voltage through a resistor to limit the current. Something like 47K to 100K and a 130ish volts ought to do as a first experiment.
You will find one of the pins is the common anode which goes to the positive of the supply. There is a separate pin for each of the digits which goes to the negative of the supply. Usually you can dope out the connections by close observation of where the leads go inside the tube.
There used to be ICs made just to drive these things. You can probably turn up data sheets and probably parts with a little Googling.
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On Mon, 18 Sep 2006 01:52:40 GMT, "Tom Gardner"

They are just special neon lamps. They take something over a hundred volts to fire (light) and then the voltage drops back to around 90 volts.
One precaution. They will draw as much current as they can - to the point of destruction. Apply the voltage through a resistor to limit the current. Something like 47K to 100K and a 130ish volts ought to do as a first experiment.
You will find one of the pins is the common anode which goes to the positive of the supply. There is a separate pin for each of the digits which goes to the negative of the supply. Usually you can dope out the connections by close observation of where the leads go inside the tube.
There used to be ICs made just to drive these things. You can probably turn up data sheets and probably parts with a little Googling.
-- W§ mostly in m.s - http://members.1stconnect.com/anozira
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A young fellow I know is in an engineering program at the local college. He was assigned to design and build a nixie tube clock as a course project. He seemed not to have any great problem finding any of the parts he needed.
Jerry
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Jerry Foster wrote:

I wouldn't have any problem, either. Other than cleaning my shop enough to dig out all the parts, first.
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On Thu, 21 Sep 2006 12:57:07 GMT, "Michael A. Terrell"

How many "peanut" tubes do you have? I have four of them, one in a tuner, two in audio amplifiers, and one spare. Gerry :-)} London, Canada
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    [ ... ]

    Do you mean the "acorn" tubes? I know that I have one in a plastic drawer, and I think that I have some more in an emergency transceiver.
    There are also the "pencil" tubes, with the flat pinched bases with in-line pins. I've got a few around somewhere, plus about six or seven in the GR 1551-c Sound Level Meter.
    Plus one rather interesting tube, all ceramic and metal, with "pins" being flat extensions of the seals between ceramic rings. From counting the pins, it must be a triode, and rather high frequency as well. Total diameter (exclusive of the "pins") is about 3/8", IIRC.
    Plus at least one "lighthouse" triode.
    As for Nixies -- most are in old test equipment.
    Enjoy,         DoN.
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I had a calculator by Cannon that used Nixie tubes. It cost $600.oo USD and was sold in business supply stores only - 4 banger with memory - wall plug - and 3 or 4 years before the TI SR70 I think that was the number... Before I could buy any other calculator - so I got that one. It finally went to the scrap box about 5 years ago - was in the shop as a desk box for some years.
Martin
Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member http://lufkinced.com /
DoN. Nichols wrote:

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On 22 Sep 2006 02:45:10 GMT, snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

No, these are about 5/8" dia. by 2 1/2" high with a Bakelite base like the metal base on a dual filament auto bulb but only one locking pin, four contacts on the base similar to the auto bulb. IIRC the filament voltage is 1.1V but each tube had a rheostat and a peek hole to visually adjust the voltage to give a red glow to the filament strand. I don't recall the "B" & "C" voltages offhand but I think they are specified on the amplifier units which were commercially produced while the tuner was home built, or maybe other way about, I haven't had these down off the shelf for a number of years. Each unit is housed in a wooden box with binding posts to link them together. I have many other odd ball tubes including a Westinghouse WD12 which is very similar to the peanut tube but about twice the dimensions, and some of the (pencil ?) tubes from early hearing aides. Gerry :-)} London, Canada
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Gerald Miller wrote:

I have a couple dozen different nixie tubes in a half dozen older HP frequency counters that I want to restore.
<http://home.earthlink.net/~mike.terrell/Projects.html lists five of them, plus there are one or two more that I can't reach right now. Most of the contents of my electronics shop is still covered in layers of 4 mil plastic from the last several years of hurricanes.
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Gerald Miller wrote:

I do have some 1AD4 flat subminiature tubes.
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On Thu, 21 Sep 2006 12:38:48 GMT, the renowned "Jerry Foster"

If the project was intended to simulate a real design (for production) process, I hope the prof docked marks if he designed in any obsolete or obsolescent parts, no matter how nicely they seemed to fit the job. It's really a major problem in many segments of the electronics industry.
Best regards, Spehro Pefhany
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    [ ... ]

    Given that Nixies were a part of the product specification, obsolete (or obsolescent) parts were already part of the given project -- the Nixies themselves.
    Enjoy,         DoN.
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On 22 Sep 2006 02:47:48 GMT, the renowned snipped-for-privacy@d-and-d.com (DoN. Nichols) wrote:

Good point, but of course that part was beyond the designer's control. ;-)
Best regards, Spehro Pefhany
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They are simply neon tubes - look at them and trace out the pins. Design a circuit like a 100k resistor and 120V DC and it should glow. If to bright - increase resistance. The voltage can come down a little, but not much since the units need maybe 63-90 volts.
Martin If you really want something to design around them - I have some designs around here very likely. Just a mater of time and a scanner. Martin H. Eastburn @ home at Lions' Lair with our computer lionslair at consolidated dot net NRA LOH & Endowment Member NRA Second Amendment Task Force Charter Founder IHMSA and NRA Metallic Silhouette maker & member http://lufkinced.com /
Fred Fowler III wrote:

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