Lighting up a DM160

[Paul Andrews]

I just impulsively bought some DM160 VFD indicators and now I am at a loss as to how to power them! Can anyone help?

[Dylan Distasio]

Are you asking specifically about how to get the different required voltages in practice or what the voltages/current/pinouts are in the first place?

If the latter, this is a pretty well explained datasheet:

http://www.mif.pg.gda.pl/homepages/frank/sheets/009/d/DM160.pdf

On Thu, Mar 9, 2017 at 9:32 PM, Paul Andrews <pa...@nixies.us> wrote:

I just impulsively bought some DM160 VFD indicators and now I am at a loss as to how to power them! Can anyone help?

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[judg...@gmail.com]

Thanks. That got me started finding some more info too. I might be back if I don’t get anywhere with the practicalities!

 

From: Dylan Distasio
Sent: Thursday, March 9, 2017 9:51 PM
To: neoni...@googlegroups.com
Subject: Re: [neonixie-l] Lighting up a DM160

 

Are you asking specifically about how to get the different required voltages in practice or what the voltages/current/pinouts are in the first place?

 

If the latter, this is a pretty well explained datasheet:

http://www.mif.pg.gda.pl/homepages/frank/sheets/009/d/DM160.pdf

 

On Thu, Mar 9, 2017 at 9:32 PM, Paul Andrews <pa...@nixies.us> wrote:

I just impulsively bought some DM160 VFD indicators and now I am at a loss as to how to power them! Can anyone help?

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[Paul Andrews]

Boy did I buy myself into a hole with this one! I had just about got to grips with Nixie tubes, now I have a whole new technology to learn; I'm sure a lot of the folks on this list know the ins and outs of triodes - I'm not one of them! I will get there eventually though.

Apologies if what follows seems impossibly naive. That's because it is!

It seems there is no getting away from driving the anode at 50V. I'm currently trying to figure out how I can do that given what I have on hand, before I order the parts I need to build an actual 50V supply. Basically buying a bunch of 9V batteries or making a simple voltage divider for one of my nixie power supplies.

I am a little concerned about limiting the current. Do I have to or will it just draw the current it needs?

I'm also slowly wrapping my head around -Ve voltages. I think I am gathering that the filament is held at a constant voltage and then you tweak the grid voltage to make it +Ve or -Ve with respect to that. Or maybe the other way around. I've not quite got that straight yet! Most of what I can find on the web wants to make oscillators or amplifiers or VU meters out of these. All of which sounds like fun, but right now I just want to light one up!

[Paul Andrews]

Well I got one lit up, having blown one. It is kind of dim though - when I pull the plug on it it brightens considerably. I am clearly not getting something.

[Paul Andrews]

Finally I get it. If anyone is interested I will work on a schematic. I should probably do that for my own benefit anyway.

[Paul Andrews]

A closeup of the filament structure. This is what attracted me to these tubes. Now I just have to figure out what I want to do with them!

[Dylan Distasio]

I'd be interested in your schematic, thanks.  

On Mar 11, 2017 8:36 PM, "Paul Andrews" <pa...@nixies.us> wrote:

Finally I get it. If anyone is interested I will work on a schematic. I should probably do that for my own benefit anyway.

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[Manuel Azevedo]

Me too please!
Thanks!

[Roddy Scott]

Make a binary clock!

[Paul Andrews]

Here is a schematic. Some notes about it: The filament (aka the cathode) should always have 1V across it. It has to be warm. When it is warm it has a resistance of about 30R. So the purpose of the resistor network there is that it cuts the 12V up into 3V, 1V and 8V (approximately). The filament is raised to 3V above 0 because we need to be able to vary the grid voltage from -3V to 0V with respect to the filament. So in this case, with the filament held at +3V, we can vary the grid voltage from 0V to +3V. When the grid is at 0V (-3V wrt to the filament), the lamp is fully off. When the grid is at +3V (0V wrt the filament), the lamp is fully on.

I made the grid voltage variable with the little resistor network off to the left, just to demonstrate this.

I created the 50V anode potential with a 200K/100K resistor network across a 150V nixie power supply I happened to have. BTW, the tube will glow with an anode voltage all the way down to about 23V, so 3x9V batteries in series would be enough to get a glow out of it.

In reality my 12V power supply was more like 10.5V so the resistor values I used were a little different. Also, the resistance from the anode to ground is not infinite, so the actual voltage of my nixie power supply was more like 220V, which I produced gradually to make sure I didn't go over 50V. Obviously an actual 50V power supply would be better!

All of this is just to demonstrate the principles of the DM160, rather than to act as a recipe for how they should actually be controlled! I broke two lamps while experimenting, in different ways. In the first lamp I applied >1V to the filament and it burned out after a few seconds!. Second, a filament shorted to the grid so I couldn't control the grid voltage any more. The first problem was just me being dumb. I have no idea why the second problem occurred, so you have been warned! Fortunately these lamps are cheap, but I am concerned that there is no apparent reason for the second problem...

[Manuel Azevedo]

Thank you!

[Paul Andrews]

An important point: The current through the filament should be 30mA. That is the real reason why resistor network is like it is. A = V/R. Where V=11 (the voltage we are throwing away from the 12V supply, R=370 (100+270). So A = 11/370 ~= 0.03.

[Tidak Ada]

Look also for uranium glass stuff, especially marbles what are also good sources.

 

eric

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[Dekatron42]

Here's some more information on the DM160: http://www.r-type.org/exhib/aai0056.htm where you can see them being used in mainframe computers. We used a small testplug with a row of DM160 to push over the pins on the backplane on mainframe computers (don't remember if it was a Siemens or an IBM mainframe though, could have been an Amdahl to) to check the logic level signals. A few books describe these DM160 complete with the circuit diagram used to interface them to transistor logic.

One thing that almost all circuit diagram points out is the use of a grid resistor from 100K to 1M to limit the grid current. Some people have even built small amplifiers out of these, they are triodes so why not. Just google "vfd triode" or "nutube" that Korg/Noritake named theirs.

/Martin

[Nick]

The DM160/6977 is a really well explored tube - as pointed out elsewhere, it's essentially a sub-miniature vacuum triode with a fluorescent coating on its anode - this is the basic principle used by all VFD displays - the DM160 is just an early exponent.

Thus, rules pertaining to how valves/tubes work, specifically the biasing of the grid, need to be respected. Many people have posted schematics of using the 6977 in interesting ways - it's a fun device.

Attached is an article from 1968 discussing indicator tubes generally, including the DM160/6977 - worth a read!

Cheers

Nick

[Nick]

While the DM160 was the first "VFD" (about 1958), Noritake claim the invention of the digit display.

Their web site is a goldmine of information - start with https://www.noritake-elec.com/technology/general-technical-information/vfd-operation

They also produce a VFD variant that is specifically designed for audio use: the NuTube 6P1, see http://www.nutube.us/ - that's the USA distributor - it's actually Pete Millett, who some here may know for his many DIY audio designs.

Nick

[Thomas Kummer]

What does the dotted line from the ground to the 50V line mean? Did you short it? I bought some of these and have been studying your schematic, but I cant figure out what that means. 

[Paul Andrews]

It just shows that the 50V is relative to ground. So the 'ground' of the the 50V supply and the ground of the rest of the circuit are tied together.

I'm putting 'ground' in quotes, because it is really 0V. 

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[Thomas Kummer]

I gotcha so would this circuit work? 

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