Welcome to Laser Pointer Forums - discuss green laser pointers, blue laser pointers, and all types of lasers

LPF Donation via Stripe | LPF Donation - Other Methods

Links below open in new window

ArcticMyst Security by Avery

First HeNe (Help)

Joined
Mar 27, 2013
Messages
2,416
Points
63
So I finally got my first gas laser... a simple 0.5mW 632.8nm Melles Griot HeNe off of eBay. It's a 05-LHP-214, with a Laser Drive 106T power supply outputting 1250V DC@4.0mA (input 12VDC@1.5A). Now here's the interesting part... the laser powers up as soon as I plug in my charger for my PSU (a simple wall charger off of Amazon that ouputs 12VDC @2.0A), stays on and stable for about 15 seconds, then flicks off, sometimes sputtering a bit. There is a very quick arcing/sizzling sound when the laser flicks off. If I short the Alden connector and then plug the laser back into the PSU, the cycle repeats.

I haven't been able to find any power requirements on this particular model, I'm wondering whether this power supply is feeding the correct amounts. The laser is about 177mm by 31mm, and by my research is quite similar to the 25-LHP-213 offered by MG right now. However, I can't find any info on that laser either, other than the fact that it uses "Power Supply Type A" :thinking:

Since I bought the laser and power supply together from eBay, I thought the PSU would match the laser... and if so, what could be going wrong?

Thanks so much :beer:

I get to enjoy glorious 632.8nm light at 15 second intervals :na:

EDIT: Oh and my HeNe is a laser head, if anyone has a (bare) laser tube and power supply, or a (bare) laser tube that is compatible with my power supply, and he/she is willing to sell it, I'm interested :beer:
 
Last edited:





Joined
Dec 17, 2012
Messages
2,081
Points
63
All my tube issues were due to my ballast being incorrect. Whats the ballast resistance?
 
Joined
Jan 2, 2008
Messages
1,513
Points
83
First thing I might try is upping the wall-wart power. Sounds like it's not getting enough power to the HENE power supply.


All my tube issues were due to my ballast being incorrect. Whats the ballast resistance?

I thought that, but it sounds like a sealed tube, not a bare tube (said "LASER HEAD") - if so, he doesn't have access to the ballast resistor.

If it is a bare tube, you are probably right and it's not stablizing because of the ballast resistor. Or he might not have one at all
 
Last edited:
Joined
Mar 27, 2013
Messages
2,416
Points
63
Well I dug out my good old analog multimeter, it's saying the wall wart is outputting 12.35V at the leads when not connected to anything. I'll need to do some more testing, maybe the output is dropping after I plug in the laser or something.

And yes this is a sealed tube. Interesting note: the cable leading into the back of the laser tube is rather loose, I can lightly tug it out or push it in a couple mm. Not sure if that helps but just an observation.

Oh and the tube has two sets of 6 glue/silicone/whatever plugs alternating set screws and glue, in case I need/decide to open it up.

Thanks :beer:
 
Joined
Mar 27, 2013
Messages
2,416
Points
63
Ok the wallwart gives just around 12V throughout, it drops only a little with the laser plugged in and running. I can't test the current with my multimeter, I'll need to go grab a better one tomorrow.

Any ideas? Thanks
 
Joined
Apr 26, 2010
Messages
4,175
Points
83
I had this problem when trying to use a wall phone charger to power a laser diode. The charger had a current output that I believe coupled with the driver's output, killing my diode.

So you may have 4.55mA going to the tube

Or, even if the PSU meets the tube's requirements, they can still be incompatible. So stop trying to run it if it only goes for 15 seconds! That's an obvious sign something is WRONG!

Also, and I think this should have actually been first, you are 100V SHY of the requirements of the tube! Tube needs 1350V, and you're giving it 1250V!

What is the length of the tube? Down to mm if possible.
 
Last edited:
Joined
Mar 27, 2013
Messages
2,416
Points
63
Well my sealed tube is sealed no more, it's quite bright and lasing nicely now (at least for now) :D not sure why, but it seems to be working fine now. Bright orangish plasma with a hint of pink. The tube does get quite warm after a 5-10 minute run though (along with the ballast resistors, which turned out to be 2 35k +/- 5% in series). All I can say about the size is that it is right around 177mm by 31mm before I dissected it (which turned out quite simple, to my surprise). I really hope this PSU is compatible with the HeNe :undecided:
 
Last edited:
Joined
Dec 17, 2012
Messages
2,081
Points
63
I pulled a tube out of its enclosure and it no longer worked with the exact same ballast. Could have been loose anode and cathode connections?
 
Joined
Jan 2, 2008
Messages
1,513
Points
83
I really hope this PSU is compatible with the HeNe :undecided:

I had that same worry with a yellow that had, what appeared to be, an underpowered power supply. Sealed head and no labels.
It ran fine always, but the HeNe driver was way underpowered for what a yellow should be.

I took to SELEM and asked Sam Goldwasser.

He said if it is happy, leave it alone. Happy meaning not sputtering or having any issues.
 
Last edited:
Joined
May 1, 2009
Messages
181
Points
28
Have the same issues with my HeNe tubes if the PSU doesn't provide the proper current or the supply voltage of the PSU is too low.

The tubes start to flicker and do make some quite strange noise.

Guess you'll be happy with some new PSU or power supply.
 
Joined
Mar 27, 2013
Messages
2,416
Points
63
Hmm well it seems to be working properly now that it's a bare tube... :thinking:
 
Joined
Mar 10, 2013
Messages
2,918
Points
113
Well, the tube is capacitive so perhaps the cylinder was causing an issue with the circuit somehow? Then when you took it out it works fine? :thinking:
 
Joined
Mar 27, 2013
Messages
2,416
Points
63
Perhaps, although it was potted with rubbery-silicone like stuff so the casing shouldn't have caused an issue :thinking:
 

lzrppl

0
Joined
Oct 6, 2012
Messages
11
Points
0
I believe that the tube was probably arcing to the case somewhere along its length. I am sure that was the sizzling sound you heard. HeNe power supplies are arcing little muthas. First they have to output high voltage, low current electricity to break down the gas and once it starts the population inversion to start lasing it falls back to a couple of hundred volts and 4 to 15, 20, 25ma or so...depending on tube length. Very similar to old school neon circuitry. I had a few of this model back in the eighties and a few others...like Uniphase with a much smaller diameter. You would be lucky to get more than 2 mW out of a 6 to 8 inch HeNe.

Jus' Sayin'
 
Joined
Mar 10, 2013
Messages
2,918
Points
113
This was kinda my guess as well, and by doing this it adds resistance to the circuit, and i'm betting it just brought it down to near the dropout threshold, causing it to sputter.
 




Top