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#51 BSJ

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Posted 23 August 2013 - 01:56 PM

Does FL ever have "dry" air? I mean like in the teens or lower...

#52 WarmWeatherGuy

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Posted 23 August 2013 - 01:59 PM

Does FL ever have "dry" air? I mean like in the teens or lower...


It happened once, and it caused the Space Shuttle to blow up.

#53 BSJ

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Posted 23 August 2013 - 02:09 PM

That was cold temps. Not precent of humidity...

#54 nevy

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Posted 23 August 2013 - 02:18 PM

Mine works below freezing, you can stick mine in a freeza for 30 minutes and it still works , the beam is a bit spread out for a second or two but once the ice crystals are burnt off of the laser outer lense it's back to to normall thin beam , you gets what ya pay for.

#55 WarmWeatherGuy

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Posted 23 August 2013 - 02:20 PM

That was cold temps. Not precent of humidity...


Ah, you're right. I saw the word teens and thought you were talking temps (I thought YOU had confused the two when it was ME). Humidity is usually 99 to 100% here. On an extremely dry day it might go down to 50%, usually in the Winter. If it ever goes below 50% then Florida catches on fire.

I lived in Las Vegas for a few years. I bought a cheap "leather" strap to wrap around my steering wheel in my car that had no air conditioning. Over the years I guess it had absorbed a lot of palm sweat. I drove my car to St. Pete. to visit my parents and my steering wheel covering instantly turned to putty and had to be thrown away.

It really sucks here in Florida as far as astronomy is concerned. I am working on moving to Arizona or New Mexico.

#56 Qwickdraw

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Posted 23 August 2013 - 03:37 PM

As a counterpoint, when sharing the sky with the general populace rather than a group of fellow crotchety curmudgeon astronomers, I'd say the GLP is the most significant tool in the last two decades to be introduced into the hobby. I think it comes down to context and purpose. GLP finders are far less destructive of a dark sky experience than the light generated by a laptop or two, yet I don't see vehemence directed at imagers. :shrug:

- Jim


That's where the star party "Hierarchy" comes in . And why I don't bother with that function any longer .
I've never been able to understand why someone who wants to do serious imaging , would want to do it at a star party .
Have star parties now become an activity where rules are set in place to favor only one aspect of the hobby ?
The hierarchy that looks down their noses at the hobbiests whom enjoy the simplicity of the visual aspect and another example of "do as I say , not as I do " .


I don't know that it is necessarily that as much as having dozens of people around all waving lasers is a recipe for an accident.

#57 Mike B

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Posted 23 August 2013 - 03:59 PM

Yes, lasers certainly "light-up" notably more in foggy/dusty conditions, for the reasons stated, but the ones i've had the pleasure to use still work just fine in dry, clear air.

I thought back to my experience and realized it was in my driveway.

Moonlight will also make the laser's beam hard to see- especially when aimed near Luna. 'Tis an interesting exercise, to be sure- using a GLP as your scope's primary pointer, and then trying to guide it to the Moon! You almost have to "leap" that last 15 degrees, by intuition.
:bangbangbang:

#58 Wmacky

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Posted 23 August 2013 - 09:45 PM

Mine works below freezing, you can stick mine in a freeza for 30 minutes and it still works , the beam is a bit spread out for a second or two but once the ice crystals are burnt off of the laser outer lense it's back to to normall thin beam , you gets what ya pay for.


Which brand / model is that?

#59 nevy

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Posted 24 August 2013 - 08:50 AM

Mine works below freezing, you can stick mine in a freeza for 30 minutes and it still works , the beam is a bit spread out for a second or two but once the ice crystals are burnt off of the laser outer lense it's back to to normall thin beam , you gets what ya pay for.


Which brand / model is that?


I bought them from howie glatter.


#60 hottr6

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Posted 24 August 2013 - 09:40 AM

Mine works below freezing, you can stick mine in a freeza for 30 minutes and it still works , the beam is a bit spread out for a second or two but once the ice crystals are burnt off of the laser outer lense it's back to to normall thin beam , you gets what ya pay for.


Which brand / model is that?


I bought them from howie glatter.

That's interesting. If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F). Are you referring to another unit? I'd like to know what powers it, because even Li-ion chemistries fail when water starts to thicken.

The other explanation is that many British refrigerators are made by Lucas, "Prince of Darkness", inventor of the 3-position switch (on, off and flicker), so it is unlikely that your freezer works. :lol:

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#61 hottr6

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Posted 24 August 2013 - 09:54 AM

...my GLP works fine from 7500' MSL mountain tops in northern Arizona. You'd have to go to Antarctica to find cleaner and drier air!

My GLP works fine at 7,500' in NM (except when it gets cold). I'm 2,500' lower than MRO (2 miles from me), and 1,000' higher than VLA (20 miles away), and those locations were chosen for their low humidity.

I've tried GLPs in Antarctica. Even when kept in a pocket they don't work, but I would not expect their consumer-grade Li-ion batteries to work at sub -20F.

For our dark and cold stations that operate through the year, we use Lithium Thionyl Chloride batteries with hybrid layer capacitors (HLCs) to provide power during high current (mA, that's high for our gear!) demands. Even then we have to derate the batteries by 400%. We'll bury a ton of batteries in the ice to run the equivalent of a 5w bulb through the winter.

Remember that the "temperature" of a battery used in manufacturer's data sheets is the average temperature of the battery in the previous 24 hours.

#62 Howie Glatter

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Posted 24 August 2013 - 03:00 PM

"If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F)."

www.energizer.com :
The recommended operating temperature range for alkaline batteries is -18° C to 55° C. . . The Alkaline-Manganese Dioxide cell can operate at temperatures as low as –20oC however this performance will be significantly lower. ."

Most of my pointers are highly cold resistant. I usually test them at 1 degree C.

#63 nevy

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Posted 24 August 2013 - 05:21 PM

Mine works below freezing, you can stick mine in a freeza for 30 minutes and it still works , the beam is a bit spread out for a second or two but once the ice crystals are burnt off of the laser outer lense it's back to to normall thin beam , you gets what ya pay for.


Which brand / model is that?


I bought them from howie glatter.

That's interesting. If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F). Are you referring to another unit? I'd like to know what powers it, because even Li-ion chemistries fail when water starts to thicken.

The other explanation is that many British refrigerators are made by Lucas, "Prince of Darkness", inventor of the 3-position switch (on, off and flicker), so it is unlikely that your freezer works. :lol:


Trust me , it works in the cold, if it didn't then I wouldn't say so.
So everyone needs to stop using their telrad in the cold because they use AAA batteries because “ it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F)." :roflmao: :lol:

#64 nevy

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Posted 24 August 2013 - 05:22 PM

And my freeza works just fine too ;-)

#65 Robert Cook

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Posted 24 August 2013 - 06:45 PM

That's interesting. If this is Glatter's "SkyPointer", it is powered by AAA batteries and no way will AAA deliver electrons when it gets cold (below 50F). Are you referring to another unit? I'd like to know what powers it, because even Li-ion chemistries fail when water starts to thicken.


Not to pile on, but here is a fairly convincing "torture test" (of a flashlight and its battery):
http://www.candlepow...ght-Torture-...

That's a standard 3V (nominal) Li-MnO2 cell, but in practice I've found 1.5V (nominal) Lithium AA and AAA cells using Li-FeS2 chemistry to be at least as robust (and probably even more so). Quality NiMH AAA cells (e.g. Eneloop) can also take a real beating and continue to function--50°F would be no problem for them.

Now, alkaline batteries (Zn-MnO2) aren't nearly as tough and can begin to sag (in voltage) and fail under adverse conditions, but well-designed circuits should be able to draw enough current from them to continue to function under most conditions that we'd be willing to subject ourselves to (without a parka). Devices that require a certain narrow voltage range and flawless battery performance may fail with alkalines when temperatures get chilly, however.

#66 hottr6

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Posted 25 August 2013 - 10:13 AM

www.energizer.com :
The recommended operating temperature range for alkaline batteries is -18° C to 55° C. . . The Alkaline-Manganese Dioxide cell can operate at temperatures as low as –20oC however this performance will be significantly lower. ."

I've tried 3 different sets from different production runs of this very same battery and they fold at 50F in my Z-Bolt. That's my experience. :shrug:

#67 nevy

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Posted 25 August 2013 - 12:51 PM

I use duracell , I've not had any problems with failure in the cold

#68 Howie Glatter

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Posted 25 August 2013 - 02:53 PM

Hi Shane,

" . . they fold at 50F in my Z-Bolt. That's my experience."

Have you measured the current draw ? This is easy to do if you have a multi-meter current function with low series voltage drop (0.2V or less). Just remove the battery cap and put the meter probes to the battery and case.
Many sellers boost the drive current to get reasonable output from low-efficiency crystals and optics, but high current will disproportionately reduce alkaline cell
low-temperature performance (as well as give short infra-red laser diode lifetime).
If your current is 350 or more milliamps, that might cause the batteries to suffer in the cold. I run my pointers at around 260 ma.
I believe that variation in the quality of the optically active crystals with respect to energy conversion efficiency over temperature, is the biggest factor that kills low temp. performance.

#69 jrbarnett

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Posted 25 August 2013 - 09:11 PM

Use lithiums.

- Jim

#70 MikeCMP

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Posted 25 August 2013 - 10:57 PM

Are there any GLP that run off of AA instead of AA? AA last way longer.

I think the reason the GLP's fail in the cold is most of the cheap ones are IR pumped. They need the heat in order or function. The best way for one to work in the cold would be for you to get a GLP with a diode,min stead of IR pumping. But, I think the green diodes are pretty expensive.

Mike

#71 hottr6

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Posted 27 August 2013 - 02:14 PM

Good tip Howie, I'll try that. Thanks.

I disappeared for a couple of days, but before I left, I popped my lasers into the fridge. I took two photos, one when I placed them in the fridge, and the other, 2 hours later.
The first photo on the left showed all three beams glowing brightly. After 2 hours, when the GLPs were turned on, they were momentarily bright for, I guess, half a second before going dim. The RLP was unaffected.

Then I popped them into the freezer for 30 minutes. The Z-Bolt did not light at all, and the Jasper was fainter still. The RLP remained unaffected.

Batteries: In the Z-Bolt, AAA Energizer "Ultimate Lithium" Li/FeS2. In the Jasper, CR123A Li/MnO2, and the RLP (actually, a collimator) AA Rayovac alkaline-manganese.

Hardly a scientific experiment, but this is typical of the tests I have done with different battery chemistries in these lasers, and all with the same results. The dimming after a brief time indicates something in the circuitry that is responsible.

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#72 nevy

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Posted 27 August 2013 - 06:01 PM

I don't think it's your batteries that are not working in the cold , I think it's the actual laser.

#73 MessiToM

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Posted 27 August 2013 - 07:16 PM

Yes its the IR laser diode that is pumping your GLP suffering ^

I just set mine to kill and she likes it! lol
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#74 hottr6

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Posted 28 August 2013 - 01:10 PM

I don't think it's your batteries that are not working in the cold , I think it's the actual laser.

I'm thinking it is a combo of both. What I *think* may be happening (I'm no engineer!) is that the cold does effect the initial transient of current coming from the battery, which fools the circuitry into doing something different. I don't see the moderate cold effecting the laser circuitry because most consumer electronics is rated to near freezing, so I infer that my observations are due to how a battery reacts to rapid changes in load at different temperatures (there is a lot of quantitative evidence to back this up). Bottom line: The battery and laser circuitry are not well-matched.

I would wager that if I used a high-quality linear DC power supply we would not see GLP dimming with cold.

#75 hottr6

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Posted 28 August 2013 - 02:32 PM

Yes its the IR laser diode that is pumping your GLP suffering ^

Is there anything a mere-mortal can do to fix this? Is there a pot that can be adjusted?






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