New Host Mini BR!!!

[Kai]

No resources...

 

[IgorT]

I'm sure some people close to you would be willing to test it for you.

People are sending lasers back and forth for this purpose all the time.

 

[Kai]

It finally crapped out on me was hoping I'd at least get a chance to measure the output but the meter has yet to arrive. So there you have it folks; 1 week at 150mA then 3 weeks at 175mA. Output: Destructive!!!! hahaha the new diode is in and is currently set to a more conservative 110mA still waiting for the meter to get here. Check back for a new host in the near future

 

[IgorT]

Well.. Looks like i'm not the only one, who's PHRs die at high currents..
3 weeks at 175mA is not bad tho.. How many minutes per day?


Oh and what kind of meter are you getting?



Otherwise, if you want to push it, i think you'll be better off with a larger host and a heatsink. This tiny host is cool because of it's small size, and it's awesome to have that much power in such a small shape, but even tho PHRs don't heat up too much, they do need some kind of heatsinking at high currents..


I'll use these tiny hosts for the many weaker PHRs i find in each batch, and set them to 90mW or so. That shouldn't kill them.. Climbak had one running at 80mW for three months or so without a break.

 

[Kai]

I average around 20-30 minutes a day. Dropped it a couple times too. And the can was cut open. So I guess 4 weeks at >150mA isn't so bad...? I'm getting a laserbee power meter. should be here by Monday.

 

[IgorT]

20-30 minutes a day and a month? That's a lot..

I mean, i left mine on for 60-90 minutes a day, and most of this was either a 30 minute temp. measurement (heatsink testing), or simply survivability testing, the other largest part was 20-30 minutes at night, and the rest, when i picked it up every now and then and powere it up for a minute or two.

On the last one i noticed power degradation afer just a few hours of total run time. After 15 hours, the power was almost 10mW lower, but it didn't want to die. So i set it to 188mA, where it did 200mW after a 405nm AR coated glass lens long enough for me to take some pictures, and then it died. It would have done more, if it didn't degrade before.

I killed it on purpose, as i knew it wouldn't last much longer (they never do when the power starts dropping) and i wanted to make room for a 6x.. :


20-30 minutes a day for a month is around 12.5 hours.. That fits in with my observations....

 

[daguin]

I average around 20-30 minutes a day. Dropped it a couple times too. And the can was cut open. So I guess 4 weeks at >150mA isn't so bad...? I'm getting a laserbee power meter. should be here by Monday.

Was it warm when you dropped it (either time)? How many minutes long was your longer (longest) runs?

Peace,
dave

 

[IgorT]

Oh, you dropped it? Several times? I missed that..

I would also be interested in the average runtime duration.. Especially since it didn't have a heatsink.

 

[Kai]

The 2 times I dropped it, it was off. Hmmm I just had a thought. What if the big bulky heat sinks had an adverse affect on transferring heat? Like an obstacle for the heat to reach the outer surface area of the host to be dissipated into the air? Wouldn't the big solid heat sink be like extra mass for the heat to have to overcome before it reached the outside? I guess what I'm getting at is if the heat takes more time to get through all that mass, wouldn't it remain around the diode for longer?

 

[Maven]

i think that is why you get a metal that is not an insulator and transmits heat quickly then the next most important thing is surface area

 

[daguin]

The 2 times I dropped it, it was off. Hmmm I just had a thought. What if the big bulky heat sinks had an adverse affect on transferring heat? Like an obstacle for the heat to reach the outer surface area of the host to be dissipated into the air? Wouldn't the big solid heat sink be like extra mass for the heat to have to overcome before it reached the outside? I guess what I'm getting at is if the heat takes more time to get through all that mass, wouldn't it remain around the diode for longer?

Physics disagrees with your thought. Heat travels through the metal. The more metal, the more heat that can be moved. Metal to metal heat transfer is much more efficient and fast than metal to air. That is why it is called a heat "sink." It holds most of the heat, but it spreads it out in the metal so there is less heat at the diode. Eventually, yes, the metal will heat to the point where it is not taking heat away fast enough from the diode. However, the more metal, the longer it takes to reach this point.

If you don't have enough "sink" then the only heat transfer available is metal to air. Since the metal to air transfer is less efficient and slower, if there is not enough metal, it reaches the point where it can't move enough heat much faster. Instead of the heat being pulled into the metal, it remains in the diode.

The duty cycle is greatly effected by the amount of heat sinking. The more heat sinking, the longer the duty cycle. The more heat sinking, the more heat is pulled away from the diode. The more heat sinking, the cooler the diode remains.

Peace,
dave

 

[Dark_Horse]

Physics disagrees with your thought.  Heat travels through the metal.  The more metal, the more heat that can be moved.  Metal to metal heat transfer is much more efficient and fast than metal to air.  That is why it is called a heat "sink."  It holds most of the heat, but it spreads it out in the metal so there is less heat at the diode.  Eventually, yes, the metal will heat to the point where it is not taking heat away fast enough from the diode.  However, the more metal, the longer it takes to reach this point.

If you don't have enough "sink" then the only heat transfer available is metal to air.  Since the metal to air transfer is less efficient and slower, if there is not enough metal, it reaches the point where it can't move enough heat much faster.  Instead of the heat being pulled into the metal, it remains in the diode.

The duty cycle is greatly effected by the amount of heat sinking.  The more heat sinking, the longer the duty cycle.  The more heat sinking, the more heat is pulled away from the diode.  The more heat sinking, the cooler the diode remains.

Peace,
dave

That's the way they taught me too

 

[Maven]

hmm does anyone have any ideas about the heat dissipation to surface area ratio's

like how much surface area you need to dissipate x amount of heat in a second or something like that

as well as how much heat is being generated by the diode and/or the drivers ? (average or something)

 

[IgorT]

What if the big bulky heat sinks had an adverse affect on transferring heat? Like an obstacle for the heat to reach the outer surface area of the host to be dissipated into the air?

With laser pointers, heat dissipation into air is almost negligible.  It's air, that's the insulator. That's why computer heatsinks need them fins. A laser is round and smooth. That's the worst for heat dissipation into air, as it means a lot of volume and little surface - the opposite from a finned heatsink.

When you don't have room for fins and a fan, a certain mass of high thermal conductivity metal is your best bet. Like Dave said, it will saturate eventually, but it will take much longer to do so, than an AixiZ module alone.

The more mass you give it, the better. And the shape has to be right for heat to flow into all parts of it.. Thin walls are a no-no. Since the back of the AixiZ module is thin, you need to ensure good contact between the head of the AixiZ module and the heatsink. The head is quite massive, so it's good at this.

 

[Kai]

Enlightened

 

[Kai]

Ok the meter arrived today. Smaller than I thought it'd be but that's a good thing. Just got a chance to measure my BR with the new diode at 110mA; its putting out 103mW after the acrylic lens. Too bad the old diode at 175mA died before I got to measure it =/