Firing up a little argon?

[Things]

Hey guys, well I've given up on my old switchmode power supply that was blown, and bought a Uniphase 2111 power supply from daguin. I've wired up the essential connections (SHorted interlock, cathode(s), anode, ground) and the tube tries to start. I can see very brief flashes (What a beautiful colour!), however, the tube won't actually stay lit.

I have pins 1 and 3, and 2 and 13 shorted on the DB25 connector, but thats it.

The tube has been sitting around for a very long time, and has quite a few hours on it, but it's so tempted to start I'm not sure what the problem could be. Maybe the idle current is too low for this tube? Should I connect a pot up to control the current and push it a little until it stays?

I'll mention that I'm NOT using the ignitor for this PSU. I do have it, but I am using the ignitor on the tube itself. I am told that this ignitor detects when the voltage is floating, and tries to arc the tube. Once it does, it detects the voltage drop, and stops trying.

I have a video I'm uploading now.

Can't wait to get it going!

Just reading the FAQ (About the model 2214 power supply, which is supposedly the same), it says the PSU brings the current right up while trying to start the tube anyway.

Not sure what I need to do to get it to stay lit? Turn its fan off and leave the filament going for a while to warm everything up and try again?

A video: YouTube - Argon laser first light! Attempting to start

Cheers,
Dan

 

[Meatball]

Hi Dan,

do you have a way of knowing if your cathode is actually being heated?

If this tube has sat awhile, the gas may be the issue. The soft seals can simply leak over time when its not being regularly fired up now and then.

The repeated clicking tells me that the physical conditions inside the are not yet in order. Electrically, everything seems to be sound for now!

Do you know if Dave had it running and how? Or was it sold "as is" without testing?

 

[Things]

Yes, I can see the filament glowing thru the front and back of the tube.

When it sparks, it does actually lase. This says to me that the tube isn't up to air, but yes, it has been sitting for a very long time (years).

Dave did not have any info or power supplies for these heads, so he gave them away for free.

I don't think the gas has leaked, MarioMaster is telling me that usually the tubes wont lase at all, even when trying to ignite, if the gas is wrong.

The voltage between anode and cathode is floating at about 180V.

Cheers,
Dan

 

[daguin]

Hey guys, well I've given up on my old switchmode power supply that was blown, and bought a Uniphase 2111 power supply from daguin. I've wired up the essential connections (SHorted interlock, cathode(s), anode, ground) and the tube tries to start. I can see very brief flashes (What a beautiful colour!), however, the tube won't actually stay lit.

I have pins 1 and 3, and 2 and 13 shorted on the DB25 connector, but thats it.

The tube has been sitting around for a very long time, and has quite a few hours on it, but it's so tempted to start I'm not sure what the problem could be. Maybe the idle current is too low for this tube? Should I connect a pot up to control the current and push it a little until it stays?

I'll mention that I'm NOT using the ignitor for this PSU. I do have it, but I am using the ignitor on the tube itself. I am told that this ignitor detects when the voltage is floating, and tries to arc the tube. Once it does, it detects the voltage drop, and stops trying.

I have a video I'm uploading now.

Can't wait to get it going!

Just reading the FAQ (About the model 2214 power supply, which is supposedly the same), it says the PSU brings the current right up while trying to start the tube anyway.

Not sure what I need to do to get it to stay lit? Turn its fan off and leave the filament going for a while to warm everything up and try again?

A video: YouTube - Argon laser first light! Attempting to start

Cheers,
Dan

I also wrote this to you in PM, but thought it would be good for other members to see as well.

When an argon runs, the heat and pressure drive argon atoms into the metal and ceramic of the tube. As a tube sits for a long time, the argon begins to "escape" from the components. This raises the argon pressure in the tube. If that pressure gets too high, it will be hard to start. That is why we do "maintenance" burns monthly with these little lasers.

To overcome the high pressure, you need to give it an electrical "kick in the pants" to get it going again. This is usually done by shooting it with an oudin coil while it is trying to start. In the world of used gas lasers, an oudin coil is a pretty essential tool to have in your toolbox.

If you do not have one, you should get one However, they can be pricey. You may be able to build one. They do not appear to be too complex (although remember that I am a speech teacher ) Also, you could check with a neon light installer in your area. He should have a coil. You may be able to work out something with him.

Once you get it started, run it for several hours (maybe over night) to drive some argon back into the tube components.

If you didn't live on the bottom of the world I could loan you mine :beer:

Peace,
dave

 

[Things]

Thanks for the explanation. I was curious as to how heating the tube up would bring the pressure DOWN, as gas expands when heated, but makes sense.

As for the oudin coil, I don't really have $180 to blow on something I'll probably use only a couple of times in my lifetime, but I'd be up for modifying anything that could do the same sort of thing

Earlier, I hooked up an ignition coil circuit, and was zapping it to the anode connection while it was trying to fire. The results: Blowing the safety switch in the house I'm guessing it must have arced over the insulators supporting the tube to ground.

Where do you actually zap an argon tube to help it along? MarioMaster said he thinks you zap the cooling fins?

Cheers,
Dan

 

[daguin]

Thanks for the explanation. I was curious as to how heating the tube up would bring the pressure DOWN, as gas expands when heated, but makes sense.

As for the oudin coil, I don't really have $180 to blow on something I'll probably use only a couple of times in my lifetime, but I'd be up for modifying anything that could do the same sort of thing

Earlier, I hooked up an ignition coil circuit, and was zapping it to the anode connection while it was trying to fire. The results: Blowing the safety switch in the house I'm guessing it must have arced over the insulators supporting the tube to ground.

Where do you actually zap an argon tube to help it along? MarioMaster said he thinks you zap the cooling fins?

Cheers,
Dan

I don't know how similar an ignition coil is to an oudin coil. The "zap" from the coil must be constant (not pulsed).

The cooling fins are physically attached to the metal of the tube housing so that should work fine. I try to hit a tube "away from" any other connections, but have no idea if it actually helps. I do that simply because I want the current going through the tube first instead of out a ground or neutral path first.

Peace,
dave

 

[Things]

Is it common for the tube to actually lase while its trying to ignite, if high gas pressure is the problem? I would think that just helping the ionization along (When it's already being ionized enough to lase) wouldn't make much difference?

 

[anselm]

I don't know if all argon lasers are more or less the same, but maybe this helps:
Diane's Laser Page

 

[daguin]

Is it common for the tube to actually lase while its trying to ignite, if high gas pressure is the problem?

Yes.

The gas is lasing with the higher charge of the start pulse, but not maintaining the plasma at "running" current. The oudin maintains the higher current until the plasma can be maintained at the lower current.

Peace,
dave

 

[Things]

Hmm OK. I think I may have a flyback transformer laying around somewhere, maybe I can build up a simple driver for it and see if I can start it with that. I don't have nearly as much HV stuff now as I used to

EDIT: Would it be possible to use my CO2 laser power supply? It's basically just a beefed up flyback. It is adjustable so you wouldnt have to hit it with full power, + can't you just hold the electrode away from the laser a bit so it doesnt arc?

Cheers,
Dan

 

[daguin]

Hmm OK. I think I may have a flyback transformer laying around somewhere, maybe I can build up a simple driver for it and see if I can start it with that. I don't have nearly as much HV stuff now as I used to

EDIT: Would it be possible to use my CO2 laser power supply? It's basically just a beefed up flyback. It is adjustable so you wouldnt have to hit it with full power, + can't you just hold the electrode away from the laser a bit so it doesnt arc?

Cheers,
Dan

We need one of the electronics guys to get involved with this discussion.

I have no idea how your CO2 PSU works or how it would compare to the oudin.

I like the arcing
Although it does kick my wireless hub offline
Besides, if it doesn't arc onto the tube, the power isn't getting there, is it? :thinking:

Peace,
dave

 

[HIMNL9]

What type of oudin coil you want to use ?

If you want a high frequency resonant one, you must probably use a Tesla structure, and this complicates the things, for small builds ..... if instead you only want a high voltage source, you can use a Rhumkorff structure, that is, basically, an electromagnetic buzzer with an extra coil, and can be easily build also from scraps (well, almost )


EDIT: if you want to try with a CO2 PSU, i will suggest you to get a piece of HV insulated wire, and hook it to the output of the PSU through a high value (like, 1 Mohm) resistor ..... this will prevent too high currents arcs, save your CO2 PSU from voltage back-kicks, and also if something go wrong, probably the only thing that burn is the 1 Mohm resistor

 

[daguin]

What type of oudin coil you want to use ?

If you want a high frequency resonant one, you must probably use a Tesla structure, and this complicates the things, for small builds ..... if instead you only want a high voltage source, you can use a Rhumkorff structure, that is, basically, an electromagnetic buzzer with an extra coil, and can be easily build also from scraps (well, almost )

Bless you HIMNL9 :bowdown:

Peace,
dave

 

[MarioMaster]

You essentially want to make an RF energy field around the tube so the argon inside becomes excited, yet the source isn't directly connected to the tube. So if your source is capable of creating corona discharges then it's probably what you're looking for.

 

[Cyparagon]

As far as I can tell, the starting pulse is enough since it is lasing. It seems to me you just need to raise the current.

 

[hakzaw1]

GL Things... Thanks from me to all who posted. & TY for reminding me to get off my duff and run the argons.

I dont (can't) want to go thru all the above.
All night you say?

Should I do that if I have one that is a slow starter?
I normally run at idle- crank them up a few short moments then back to idle --total runs are about 20 min. in Summer and longer when Its cold as a ****** in the Winter here.

Doing my runs tonite out in the driveway. It hit the 80s here today.

Hope you will not be hearing from me on this board tommorrow.


hak