OT: Nixie Tubes

Hey all,

Was rumbling through bins of old stuff from a local estate sale and found about some old (looks like mil) hardware with lots of Nixie tubes attached. Asked the owner, and they "just inherited the junk", take it if you want... I did. I netted about 19 tubes, but have no idea how to test the "bad" ones.

So how easy is it to build a clock or something without frying myself in the process? I know they require pretty high voltage... Maybe there is a good design for a tube tester, but have not found on the net?

Some research shows I can get new ones from Russia.

Cheers,

Fred

Reply to
Fred Fowler III
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Fred, Nixie tubes are nothing more than neon glow lamps. Use the same method to light a simple neon lamp. A current limiting resistor and about 180 VAC(peak) or DC. Identify the cathode and then the individual anode leads for each character element. There is (or was) an IC chip MC7441 HV driver for decoding. I have used the little Burroughs 5840 tubes for projects. RichD

Fred Fowler III wrote:

Reply to
RichD

Hi Fred,

Some of the larger LCD displays use voltages in the same general area so there are all sorts of component and subassembly driver building blocks available surplus. You should be able to get close just wiring modules together.

Reply to
Fred R

Not so. Not even close. LCD drive is completely different.

Reply to
Boris Mohar

Hey Fred,

Is it OK to "forward" this to modeleng-list. I sent a few LARGE nixies to a fellow in California a few years back. They were about 5" tall, and had been used in a toll-booth for the customer to see the charges, etc. I can't recall who the gentleman was, or I would contact him directly, but I do recall that he is/was a collector and quite knowledgeable about the types and their operation..

Take care.

Brian Lawson, Bothwell, Ontario. XXXXXXXXXXXXXXXXXXXXXXXX

Reply to
Brian Lawson

Boris is right. A Nixie display has stacked sets of complete characters. Each character has a lead and 1-2 cathode leads. 12 total. The Burroughs miniatures are PC mounted. When a given character is on (glowing), the others will be in front of or behind. Due to the glowing, the thin (OFF) plates were hard to see. RichD

Boris Mohar wrote:

Reply to
RichD

Boris is right. A Nixie display has stacked sets of complete characters. Each character has a lead and 1-2 cathode leads. 12 total. The Burroughs miniatures are PC mounted. When a given character is on (glowing), the others will be in front of or behind. Due to the glowing, the thin (OFF) plates were hard to see. RichD

Boris Mohar wrote:

Reply to
RichD

Fred, you have WAY too much time on your hands!

Reply to
Tom Gardner

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

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Fred Fowler III wrote:

Reply to
Martin H. Eastburn

Here's a clock for ya, Fred....

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Reply to
Rick

In answer to Fred's post (that I missed). IIRC Nixie tubes need about 90V. an easy way to test them would be to use a 1M-Ohm resistor in series with the

110V mains. You should get a dim, but visible, glow out of that.

Mark Rand RTFM

Reply to
Mark Rand

Thank you, Boris and RichD, for your expositions. I know what a nixie display is. My point was that the drivers can handle the voltage and are an easy way to prototype. Some of the emerging display technologies, such as the "electronic paper" variants, also use higher voltages. I saved myself some time using subassemblies from surplus places. Just don't use the decoders.

Reply to
Fred R

Better to put a diode in series with maybe 100K. That will keep the (common) anode from glowing.

Here's the sort of circuit that could be used to drive a Nixie from

0/5V levels. In reality the 100K ** should probably be more like 30-50K.. it's a trade-off between brightness (and lighting the entire cathode properly) and tube lifetime.

(view with fixed-width font such as Courier)

------------------------------------+ | | | | 1N4006| 100K ** | ___ | ___ | o-|___|-->|--+--|___|-------+ | | | 1K 1W .----------|-----------. | | | | | | -------+---------- | | | | | | -+- -+- -+- -+- | | | 0| 1| 2| 9| | | | | | | ... | | | '----|---|---|------|--' | | | | | | | | | | + | | | | | --- 20K | | | | --- ___ |/ |/ |/ |/ 22uF/200V | 0V/5V -|___|--| -| -| ... -| | x10 |> |> |> |> | | | | | | o-------------------+---+---+------+------------+

MPSA42

Best regards, Spehro Pefhany

Reply to
Spehro Pefhany

message

Nixie

entire

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Embedded software/hardware/analog Info for designers:
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You want some 7441 i/cs to drive those nixie tubes - see this link for clock details:

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AWEM

Reply to
Andrew Mawson

Yes. I was just thinking of a quick and dirty way to check whether they were full of neon or of air!

Mark Rand RTFM

Reply to
Mark Rand

Well, that's psychosis, all right! All vacuum tubes - decimal counters, decoders and the Nixie tubes! I sure hope he used vacuum tube rectifiers in it, just to keep it "pure". Sheesh, I'd love to know how much power that monster draws!

Jon

Reply to
Jon Elson

According to Mark Rand :

[ ... ]

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.

Reply to
DoN. Nichols

According to Spehro Pefhany :

[ ... ]

"MPSA42"? Is that a driver IC? Or the transistors? Anyway -- as long as at least one digit is turn on all the time, the voltage of the anode should never get above about 90V, but if you are letting all digits turn off, the transistors should be capable of handling the expected voltage across the filter capacitor, which will be about 170V if you are powering it from a 120VAC line.

Next comes the logic to decode BCD to select the right transistors for many applications.

Enjoy, DoN.

Reply to
DoN. Nichols

According to Jon Elson :

[ ... ]

[ ... ]

It looks as though there are four versions of the power supply section -- with only the first using silicon rectifiers.

From the schematics, it looks as though all tubes are cold cathode -- though that could simply be my unfamiliarity with the German style of schematics.

It is a beautiful job -- with my only minor quibble is that he does not do the knots in the cable lacing quite right.

Enjoy, DoN.

Reply to
DoN. Nichols

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.

Reply to
Michael A. Terrell

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