Another way to isolate a P4 emitter base??

Morelite

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benighted said:
Is it possible the current could arc across 30 microns?

Not at this low voltage level, plus there is still a physical barrier between the two surfaces.
 

gadget_lover

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Just a stray thought or two.

First, if the idea of the diamond dust is to prevent the touching of irregularities in the heatsink or emitter slug, then lapping both should eleminate the problem.

Second, The P4 data sheet explicitly requires that you solder the slug to the heatink. I imagine the heat transfer from slug to base would be much, much better using solder instead of AA. You could use a lapped copper slug ( as you would a star) and AA epoxy that to the flashlight's heatsink Also lapped) after soldering the emitter slug to the "star". The increased area for the AA epoxy should conduct much more heat than the simple back of the emitter.

I have some P4s, so I guess I should just do it, huh?

Daniel
 

Anglepoise

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gadget_lover said:
Just a stray thought or two.

The P4 data sheet explicitly requires that you solder the slug to the heatink. I imagine the heat transfer from slug to base would be much, much better using solder instead of AA. You could use a lapped copper slug ( as you would a star) and AA epoxy that to the flashlight's heatsink Also lapped) after soldering the emitter slug to the "star". The increased area for the AA epoxy should conduct much more heat than the simple back of the emitter.

Daniel

If you solder the slug to the heatsink , you still have to deal with the +
( positive) base. So another layer of insulating material would be needed.

Not for me. I like to glue directly to the heat sink.
 

gadget_lover

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I shoudl have been more clear in my post.

My thinking is thus; Heat transfer is based on the temperature difference, the thermal resisitance of of the joint and the area involved. The thermal resistance of a joint is determined by the thickness of the material as well as the area of the joint.

A small contact area will always move less leat than a large one with the same resistance. That would mean that you want the best possible heat transfer at the point where you have the least contact area. The 1 sq cm of the P4 slug is that spot. A 1 inch diameter copper slug will conduct a lot more heat through a layer of AA to an aluminum heat sink than the slug would.

I think.

Daniel
 

benighted

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Theres been some contraversy on this subject, I'd just use a star for reliability purposes. You aren't going to notice the 2% output decrease anyway.
 

Anglepoise

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benighted said:
I'd just use a star for reliability purposes. You aren't going to notice the 2% output decrease anyway.

Well if you expect reliability, watch out for the some P4s that were sold by Dealer Extreme. They were a star base with the emitter soldered only on it's two electrical contacts . The actual base was just 'resting' on the star with some thermal paste, not glue.
In another post, members were complaining that they could clearly see the gap.
Turns out that their Chinese supplier was responsible and credits have/are/will be forthcoming.
 

Ra

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Why oh why, do I never hear someone about reversing the polarity within the flashlight and simply turn the battery 180 degrees ??

Or are you talking about exsisting flashlights with embedded electronics of which the polarity cannot be switched??

With my upcomming designs involving SSC-emitters, I connect the + of the battery to the body and heatsink of the flashlight.


Please help me on this one, and tell me why that isn't possible in your case..


Regards,

Ra
 

lasercrazy

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Ra said:
Why oh why, do I never hear someone about reversing the polarity within the flashlight and simply turn the battery 180 degrees ??

Or are you talking about exsisting flashlights with embedded electronics of which the polarity cannot be switched??

With my upcomming designs involving SSC-emitters, I connect the + of the battery to the body and heatsink of the flashlight.


Please help me on this one, and tell me why that isn't possible in your case..


Regards,

Ra
Would that work? Say you had a series setup, what would stop the voltage from just skipping everywhere and possibly even bypassing an led or 2?
 

starfiretoo

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In the days of dinosaurs thin mica sheets were used to electrically isolate power transistors from the heatsinks. Any comments on this for this application?
 

TaschenlampeMann

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I must be one of the dinosaurs because I used to use the mica insulators in the good ol days. Anyway, I used them as insulators when I upgraded my FireFlyIII, HDS B60 and Orb RAW to Seoul P4s. If I recall, the mica I used was only .08mm thick. Of course I still used the Arctic heatsink compounds. I didn't notice any negative effects on the beam by the change in height.
 

Blindasabat

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I believe the purpose here is to make as THIN a layer of AA as possible while still remaining reliably non conductive (the physical separation Anglepoise mentioned). At least it will be for me.

Anglepoise said:
My reason to try mixing in some Diamond grit was purely as a means of guaranteeing the physical separation of the two flat surfaces so there could never be a possibility of electrical contact. That was my concern with the P4, arrived at through reading some members posts.
However the addition of Diamond grit is probably 'overkill' if just a thicker layer of AA will do the trick. It just sounded like a neat idea. < grin>
Just slathering on AA decreases efficiency and will drop thermal transfer as AA is far less thermally conductive than any direct metal contact. AA is meant to add thermal paths that would not otherwise be touching (air is even less conductive than AA), and lapping is desireable as it decreases the reliance on AA. The diamond powder is primarily a very thin but reliable (size-wise) non-conductive barrier, then thermally conductive only as a bonus. For that alone, it is worth exploring.

If sand (Si or other) can be bought at the same grit quality for less, then I think that would be just as good an alternative. But you lose the bragging rights that you have the most thermally conductive material, diamond, in your light.

Ra has a good point about reversing the batteries, but ONLY if your light is direct drive and you have a nub for the negative contact. Just mark it very well that way very well so you don't fry it at some other point.
 

Anglepoise

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Here is a fun picture. It consist of a small 'blob' of AA + 325 grit diamond that can be clearly seen in the picture. The disk is only 0.005" thou thick and it was produced by squeezing between two flat, waxed and highly polished surfaces.

Once cured, the AA disk separated easily and was undamaged.
I am presuming the very poor adhesion was entirely due to the wax on the two flat surfaces and not the inclusion a few diamond particles in the mix.


DSCN2085.jpg
 

Anglepoise

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PEU said:
David, what's the point of using artic alumina (aluminate filled epoxy) with diamond dust?
Why not use common epoxy mixed with diamond dust directly?


Pablo

I am adding diamond solely to guarantee the electrical separation.
AA has always worked well for me , so why change. I am NOT suggesting that the use of diamond will alter in any way the heat transfer of the 'glue' used.

I am NOT advocating this. Just experimenting and offering an alternative to members that have had problems ( various posts ) with shorting out between Seoul P4 base and heat sink.
 

photon555

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Hi, I am thinking of Seouling my VIP. Any thoughts or advice would be appreciated. If I can do that sucessfully I will mod my Gladius. The idea of diamond dust as a uniform separation regulator appears appealing. I have a few questions if anyone is willing to give advice.

Is there any advantage to using the Artic Silver with the diamond grit?
What's the best way to pry off the old emitter in my VIP/Gladius?
Does anyone have any thoughts on the quality of the DE Seoul P4 emitters, not stars? Is DE an acceptable source for Seoul emitters?
Is it possible to order or acquire a low Vf Seoul emitter, or is it a lottery?
Does anyone have an opinion on the timing/availability of the next step up in led output?

I have a soldering station and experience in testing, debugging, and repairing digital and RF circuits/devices.

Anglepoise said:
Well if you expect reliability, watch out for the some P4s that were sold by Dealer Extreme. They were a star base with the emitter soldered only on it's two electrical contacts . The actual base was just 'resting' on the star with some thermal paste, not glue.
In another post, members were complaining that they could clearly see the gap.
Turns out that their Chinese supplier was responsible and credits have/are/will be forthcoming.
 

Anglepoise

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photon555 said:
Does anyone have any thoughts on the quality of the DE Seoul P4 emitters, not stars? Is DE an acceptable source for Seoul emitters?

The problems with some of the DE supplied LEDs, only surfaced with the stars. The emitter was not making a good contact to the star.
I have been very happy with Seouls purchased from member PhotonFanatic.
He seems to have a well deserved, good reputation.
 
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