turning hid on above water

[Meng_Tze]

Same here, if you look at how the passage talked about the conductance of the HID lamp, delta(t) = deltak f(P, T) exp(E,T) it can only give you a positive number.
Besides, you don't need to use a spice model in order to get the meaning of conductance. Spice model is for calculating the physical behavior of the device for the the given physical conditions e.g. applied voltage, temperature, pressure etc.

Meng, you know what? My bad, some how I have also gone too far away from the topic. Sorry for hijacking the thread.

I have to make a correction here, in the spur of the moment I mentioned negative conductance. This should be negative resistance as mentioned in a much earlier post.

 

[alo100]

I have to make a correction here, in the spur of the moment I mentioned negative conductance. This should be negative resistance as mentioned in a much earlier post.

Thank you Meng, you are right, there are devices which have "negative resistance" i-v characteristic!

 

[Spoon]

i just got an email from dwaine and he says 30 secs is fine. here from the salvo website

http://www.salvodiving.com/faq

 

[do it easy]

Wow, now I'm confused about all this negative voltage stuff...

I noticed today that my light was taking longer to strike. I would flip the switch and it would seem like nothing would happen, so I would turn it off and curse. Then I would flip it back on, take a few breaths and then it would strike. Does this indicate anything? It used to strike pretty quickly, but I've taken my light apart and did some unspeakable things to it. I think it's a miracle that it still works and is still watertight. I've also abused the bulb with frequent, repeated hot strikes.

My light did die today during a dive, but on subsequent dives, it worked fine, although it was a little slow to strike. The water temp was 45f.

Does anyone have any insight on what is going on with my light?

 

[alo100]

Wow, now I'm confused about all this negative voltage stuff...

I noticed today that my light was taking longer to strike. I would flip the switch and it would seem like nothing would happen, so I would turn it off and curse. Then I would flip it back on, take a few breaths and then it would strike. Does this indicate anything? It used to strike pretty quickly, but I've taken my light apart and did some unspeakable things to it. I think it's a miracle that it still works and is still watertight. I've also abused the bulb with frequent, repeated hot strikes.

My light did die today during a dive, but on subsequent dives, it worked fine, although it was a little slow to strike. The water temp was 45f.

Does anyone have any insight on what is going on with my light?

Not an expert, it will take another one to answer that, but I am curious about this.
Did you change the applied voltage to the bulb? One of the thread here talked about how the life of the bulb would be lowered because of that....

 

[do it easy]

Not an expert, it will take another one to answer that, but I am curious about this.
Did you change the applied voltage to the bulb? One of the thread here talked about how the life of the bulb would be lowered because of that....

Not specifically. Perhaps I damaged the ballast or something else while I was taking everything apart, but I did not specifically disassemble the ballast or change the battery configuration. The on off switch was being tempermental, so I "adjusted" it as a temporary fix until I replace it permantantly. It's a little microswitch and the arm that activates it was a little loose, so I bent it a little to improve the mechanical contact.

I suspect that all these frequent strikes are prematurely aging my bulb and I just wanted to see if what I observed were symptoms of dying bulbs. It's a WA MR11 with the 6 degree fixed focus. I should mention that I cracked the reflector and glued it back on.

 

[*Floater*]

I had been in the water for about 2 hours with the my Salvo 21W on when I got back, and it had turned dark so I kept the light burning on the surface to see what I was doing. It was hanging down clipped to my chest d-ring, but went off when it slightly banged up against my gf's tanks when I was helping her. This gave me a scare, but after about a minute or two I turned it on again to make sure I hadn't broken it. The light was fine, but it was still dark so I decided to keep it on while taking the gear off.

In total it was on for maybe about 20 min when I head the sound of glass shattering. I turned around and looked on the ground and saw some broken glass there but didn't realize what had happened immediately. My light was still burning fine. I continued taking my gear off and then it hit me, 'oh crap' the test tube had popped off and broken...

Luckily, my gave instructor had a spare test tube that fit (apparently salvo uses standard size test tubes) which he gave me free of charge. Not sure about how much those would cost or whether this would be covered under the warranty. I just got back from Mexico and have not contacted Salvo yet. Anyway, the light worked flawlessly from then on, but now I won't burn it on the surface anymore except for maybe a short test to see that it's working. In case it matters, the water temp was about 25 deg C and the outside temp was about 32 deg C.

 

[Halthron]

It sounds like the test tube may have heated up so much that a slight bump caused it to shatter.

 

[*Floater*]

It sounds like the test tube may have heated up so much that a slight bump caused it to shatter.

I think the air/gas inside the test tube expanded causing it to pop off. The light was on a table, but the head it self was pointed over the edge, so the tube dropped about 3-4 feet, hit a stone floor and shattered. I should have made it clearer in the origial post.

 

[alo100]

I'm still not sure how the HID light failed on land, I mean, I know that it's due to overheat, but still it seems to me that there should be more detail about how it fail.... One of the popular 10W HID light has a thermal circuit for heat detection + auto shut off, but some are still saying that it doesn't do the job.
Whereas all of us can see that HID are being used for sport cars and other vehicles without failing all the time. As some of the members here told me, a lot of HID lights bulbs are not designed for enclosed dive lights.... and I'm still trying to find out the factors...