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Problems with BB750 and 5W

Lichtgestalt

Newly Enlightened
Joined
Dec 8, 2002
Messages
22
Location
Germany
I have extremly short runtimes with my bb750.
"extremely" means that with a pack of fresh batteries regulation falls out after ~2 minutes.
I tried 2 different high-quality sets of batteries.
If I switch of the light, after it gets dim, and then restart it, it even lights up for only 10 seconds.
/ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif /ubbthreads/images/graemlins/confused.gif
 

lemlux

Flashlight Enthusiast
Joined
Mar 27, 2002
Messages
2,366
Location
San Diego
You have the same problem I had. The BB750 is very heat intolerant. It shuts down when too hot. The 5W application appears to be right at the ragged edge of one or two components' tolerance.

You'll need to repot the board with a substance that transmits heat well but doesn't conduct electricity.

I think my W3V McModule will be my only BB750 5W light, although I might use one for a 1W or 3W.
 

tvodrd

*Flashaholic* ,
Joined
Dec 13, 2002
Messages
4,987
Location
Hawthorne, NV
There was a discussion here about heatsinking the 750. I was serious about sawing/filing/lapping a copper penny.

Larry
 

Rothrandir

Flashaholic
Joined
Aug 17, 2002
Messages
7,795
Location
US
be warned though, that it's a crime to do that /ubbthreads/images/graemlins/wink.gif

instead, you should all ask larry to make us these:
site1038.JPG


/ubbthreads/images/graemlins/grin.gif
 

Shark

Enlightened
Joined
Feb 7, 2003
Messages
200
Location
Oswego, IL
Pennies havent been made out of copper for a long time they are actualy copper plated zink. Would just hate to see someone go through all that trouble and then find out /ubbthreads/images/graemlins/icon15.gif with that being said that heat sink looks AWSOME. I gotta have one!
 

Lichtgestalt

Newly Enlightened
Joined
Dec 8, 2002
Messages
22
Location
Germany
thx
I simply potted the hole thing in arctic-alumina, and then fixed it at the aluminium on the inside of my 3d-mag.
The contact-area is pretty small, but obviously it is enough to run longer than 6 minutes (didn't have more time to test)
 

dat2zip

Flashlight Enthusiast
Joined
Jan 5, 2002
Messages
3,420
Location
Bay Area
Chief,

Could you elaborate a little more. What is the copper looking thing in the picture?
 

Rothrandir

Flashaholic
Joined
Aug 17, 2002
Messages
7,795
Location
US
[ QUOTE ]
dat2zip said:
...What is the copper looking thing in the picture?

[/ QUOTE ]

i'm guessing copper /ubbthreads/images/graemlins/thinking.gif /ubbthreads/images/graemlins/grin.gif

very nice job cheif! is the copper heatsink making any contact with the ic?
 

Chief_Wiggum

Enlightened
Joined
Jan 17, 2003
Messages
541
Location
7000'
It's the copper slug for mounting the 5W. The only thing making contact is the tallest component on the board. I think it's a resistor??? (Not to sharp with electronics /ubbthreads/images/graemlins/grin.gif )
 

AilSnail

Flashlight Enthusiast
Joined
Jul 11, 2003
Messages
1,299
Location
Bergen, No
How come it looks disformed in the pcb end and discolored in the other? Looks nice, did you turn it on a lathe?

The tallest thing on the badboys are the inductor but a brown capacitor comes close. It's the two black boxes that get hottest, a diode and an IC.
 

Chief_Wiggum

Enlightened
Joined
Jan 17, 2003
Messages
541
Location
7000'
It's disformed, because I made it by hand with a file /ubbthreads/images/graemlins/smile.gif

It's discolored because it's actually two pieces of copper soldered together. The silver is the solder.

So then, the only component in contact with my heatsink is the inductor. The rest transfer heat only with the AA.

Although, I seem to remember Wayne saying that the BBs don't need much heatsinking, but they do need it.
 
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