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ArcticMyst Security by Avery

HeNe testing advice

Joined
Oct 3, 2012
Messages
139
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18
So I don't have a proper driver for my HeNe tube at the moment, I picked it up for $5 or $10 at a swap meet a few years back.
So I hooked it up to a micro fluorescent tube driver from an old office scanner to see if it would do anything.
I know it's terribly under voltage, just testing to see if it even worked.
It did light up, but nowhere near where it should be. It hugged the outside edge.

Is it worth procuring the right power supply, or could this be a bad tube?
I have a feeling a higher starting voltage driver might jump the right path...
Don't want to buy a power supply if it doesn't work ya know. Thanks.

Image links
Tube tag
https://drive.google.com/file/d/0B8aajJUqkMpeemk0cm40MGFmbTQ/view?usp=drivesdk

Non-lasing pattern
https://drive.google.com/file/d/0B8aajJUqkMpeak9yTzYxakRhN0E/view?usp=drivesdk
 





Joined
Feb 14, 2011
Messages
98
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18
well, 1st off... DON'T USE AC power for HeNe!!! they are polarized. using AC can damage them.
2nd, having the correct voltage and current is fairly important. (and make sure you have the ballast resistor(s).)
beware of the polarity, running them in reverse can cause damage.

what wattage tube is it?
if it's small enough, you could build a cascade multiplier to power it fairly easily.
 
Joined
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Yeah, they're not meant for AC, but a few minutes of low current AC is harmless.

The lighting pattern is caused by capacitive coupling of the AC. The discharge color looks okay to me, so it will most likely work with a proper DC PSU.
 
Joined
Oct 3, 2012
Messages
139
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1.5mw
Single mode
632.8nm
Appx. 245mm in length

From what I've read it's probably 6-10mw to power it, but I haven't found a lot of exact specs on the tube. Sam's briefly goes past these tubes, it's most of the info above.

I must of misread something earlier on the AC/DC. Thanks for the info.
I'm happy I started with the smallest psu I could find.
 
Joined
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Yep. DC only. The side with the aluminum cylinder inside is the cathode end (-). Probably runs on 1500-2200VDC ish at maybe 4-4.5mA. 10KV start. 75K should be a good ballast. It should be within about 2-3" of the tube anode. I use a trio of wirewound high wattage resistors to make up about 80K ish. That way they don't get too hot and the high-voltage start pulse doesn't break them down. The discharge color looks ok in your picture. Most modern tubes aren't known for leaking. Don't solder to the tube. I have clips if you need them. I have a few tubes that are old that date back to the 60s!
 
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Yeah that looks like it should work fine. I'm not sure what the current is on that particular tube but could be anywhere from 4 to 6.5mA. 5 is probably not a bad guess. If you start it up and it flickers then it needs more current, or your ballast is too small. Though, as mentioned above, 75K works for nearly any tube unless its absolutely gigantic or has some very oddball gas fill, or other abnormal attribute.
 
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Got it all hooked up with the right parts.
The power supply gets warm and makes an electric grinding noise so I'm assuming it's a cascading multiplier of sorts. It flickers quite a bit.
The output looks dimmer than any red key chain I've ever seen, so I'm gonna guess it's actually 1 - 1.5mw output :)

It was plugged into the ups with my computer, the lights on the keyboard started flickering oddly while the computer was off. The computer lives though.
Might want to put on a ferrite ring on the wall power supply if I can find one. I'm definitely not putting it on a circuit with anything else.

Doesn't look like anything special, but I have pics here:
https://m.facebook.com/story.php?story_fbid=740130872805672&id=667904556694971&fs=5
 
Joined
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Messages
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They're usually switchmode. There's a multiplier, but it is only active when starting the tube.

Have you forgotten the ballast resistor? I don't see one in your picture. Without it, the tube has negative resistance and will cause the power supply to shut down or continually restart. That would explain why you hear a multiplier, it would explain why the tube is flickering, it would explain the low power output, and it would explain the EMI problems with other devices.

Mr Kaiser above recommends 75kΩ, and that should be rated 5W or so.
 
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They're usually switchmode. There's a multiplier, but it is only active when starting the tube.

Have you forgotten the ballast resistor? I don't see one in your picture. Without it, the tube has negative resistance and will cause the power supply to shut down or continually restart. That would explain why you hear a multiplier, it would explain why the tube is flickering, it would explain the low power output, and it would explain the EMI problems with other devices.

Mr Kaiser above recommends 75kΩ, and that should be rated 5W or so.


This is exactly correct. You cannot omit the ballast! If you leave it running like that it will destroy the starter and will harm the tube electrodes. Hooking it up backwards will also have a similar effect and will rapidly destroy the tube. Also 6mA might be a bit too much for that tube. I can't find it in my list, it looks similar to my Spectra-Physics 88 which is 4.5mA. Bring it up beyond about five will actually make its power decrease. They can do anywhere from 1.5-3mW depending on setup.
 
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Ah, I didn't have a resistor.
I was thinking it should be internal on a supply made for lasers. I remember Ultimate mentioning it now. :/
I did make sure I hooked up the polarity correct though.

I'll start looking for a HV resistor then.
If so if I wanted the laser to use fewer mw I would just put more resistance in the ballast right? I'll start in 75K range and see how it works.
Thanks for the info.
 
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You can't really directly control the output of these. You can technically turn the current down, which will decrease the output very slightly... but if it eventually goes lower than the ballast can make up for then it will drop out. if you turn the current up it will become noisy but the power might climb and then eventually crest and decrease. Usually they are run at a stable, optimal current. Anything above or below that will shorten its lifespan. Increasing the ballast won't necessarily control the power, and if you go too high it will just stress the power supply.

75K is usually more than enough for any tube. Just don't use carbon resistors. I usually just several 10W ohmite 27K wirewound resistors in series. But a couple 5W metal oxide ones will do. Just keep in mind they will get hot.
 
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There's not really any easy clean answer for that. Normally when you would buy a tube it would have a spec sheet that would be with it that would tell you how much it is For that model. Most tubes are usually between four and seven mA, depending on length and pressure. If you had a supply that with varying current you could move it up and down and monitor effects, but that's about the most you can do. I'm not positive what that tube runs at.

If you run it for a little while and you notice it's getting extremely hot then turn it off... but generally speaking if it's just comfortably warm then that's fine. If you're just enjoying it for the beam it shouldn't matter. If you wanted to do holography or something with it then you would need to worry about it due to noise and such

It's 1.5mW rated, but that's all I can find.
 
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Yeah, same here. Very limited info on this tube.
If I can find affordable film I'd like to try holographic sometime.

It's just a tube I found for nothing at a swap meet, seemed time to get it going or get it gone. Glad it was still good.
 
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If you really want to get into holograms HeNes are a cheap reasonable starting point if run correctly. Their coherence leaves something to be desired but they're decent compared to other cheap alternatives, or a super expensive stabilized laser.
 
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