Big Red Banger using 12 to 16 Opnext HL63133DG Diodes

[planters]

I have always used bigger TECs primarily to minimize the wiring. I have also sourced the TECs from one company (lazy) and at the same time and so these are quite uniform in thickness, specified and lapped flat.
I agree that before setting this base plate up, taggalucci should carefully measure them. I suspect that if they measure out then his bigger problem will be the plate. Unless your mill's spindle is dead on square then any surfacing tool ( and you must surface raw stock) will leave a very shallow scalloping at the center of the cut. Final flattening with a surface grinder is easy and better if available.

A interesting alternative would be to use the 0.5mm thick thermally conductive pads popular in the electronics/computer area. 3M makes these as well as others and they are inexpensive and available through over-clocker supply houses. This will also remove some concern in engineering the distribution of hold down screws to avoid bending of a flat plate as it is secured. A fair amount of pressure is required if using grease or indium and the all hard and flat conventional TEC mounting.

[dnar]

Nice one Tony!

I feel a chubby coming on!

Is that too much information?

[mixedgas]

Grafoil. Comes from a local company, used for making high temp gaskets. Comes in nice flat sheets, you can cut it with scissors. Excellent thermal and electrical conductivity. Doesnt flake to short out the TECs either. Cost effective.

Similar materials made by the same company are used for CPU coolers etc in laptops and servers.

Steve

[taggalucci]

Ok then let me put it this way
Get yourself some digital calipers
And measure the thickness of all you tecs
And letme know the results
Its going to be a mirical machining job
If you can get good thermal contact across
All 16 tecs

I have always used bigger TECs primarily to minimize the wiring. I have also sourced the TECs from one company (lazy) and at the same time and so these are quite uniform in thickness, specified and lapped flat.
I agree that before setting this base plate up, taggalucci should carefully measure them. I suspect that if they measure out then his bigger problem will be the plate. Unless your mill's spindle is dead on square then any surfacing tool ( and you must surface raw stock) will leave a very shallow scalloping at the center of the cut. Final flattening with a surface grinder is easy and better if available.

A interesting alternative would be to use the 0.5mm thick thermally conductive pads popular in the electronics/computer area. 3M makes these as well as others and they are inexpensive and available through over-clocker supply houses. This will also remove some concern in engineering the distribution of hold down screws to avoid bending of a flat plate as it is secured. A fair amount of pressure is required if using grease or indium and the all hard and flat conventional TEC mounting.

4 x 3.30 mm
8 x 3.36 mm
1 x 3.38 mm
3 x 3.40 mm

So the largest difference is 0.1 mm

I don't plan to machine for the difference in thicknesses, I plan to use thermally conductive foam under pressure to deal with this. I have a sample from my industrial designer friend that provided promising results.

He recently worked on a project that required complex thermal management and they ended up using a similar approach - creating "islands of cold" in the heat sink located adjacent to the sources of heat.

Nice one Tony!

I feel a chubby coming on!

Is that too much information?

Yes, way too much info Wayne!

Grafoil. Comes from a local company, used for making high temp gaskets. Comes in nice flat sheets, you can cut it with scissors. Excellent thermal and electrical conductivity. Doesnt flake to short out the TECs either. Cost effective.

Similar materials made by the same company are used for CPU coolers etc in laptops and servers.

Steve

Grafoil sounds interesting, but I'm not sure which of their products you're suggesting would be suitable Steve.

I'm just finalising the baseplate design and will post some more when I'm done.

[kecked]

I wonder if you could use 4 of the 71 red diodes to replace all this. Considering the number of diodes the beam size can't be much different and special optics to tame the didoes would be smaller and cheaper than all this. Now if you did 12 of the 71 diodes that would be something to see! 8w or so of 638nm would be incredible.

[taggalucci]

I wonder if you could use 4 of the 71 red diodes to replace all this. Considering the number of diodes the beam size can't be much different and special optics to tame the didoes would be smaller and cheaper than all this. Now if you did 12 of the 71 diodes that would be something to see! 8w or so of 638nm would be incredible.

This is all discussed in http://www.photonlexicon.com/forums/...lashlight-Fail

This thread is about this build with the parts list shown as I pretty much have all of the parts (and have had for many months)!

So until I finish building what I already have, I'm not (personally) going to try using the 300mW or 500mW wide stripe multimode diodes (though I do have one 71 diode and some Kiyoukan optics).

The beam properties of these Opnext diodes are amazing and I'm not convinced you could achieve the same power density and divergence with multimode diodes. But this has already been discussed before.

[planters]

I agree with kecked. The problem with combining a large number of diodes is that all the problems of alignment and reliability are proportionally greater. And the larger spread of all the components is associated with more instability problems. If the absolute maximum power (forget brightness and beam size) is the goal then you need the maximum number of the most powerful diodes you can get. But, if you have a target with your current project of 2-2.5W then 4 G71's run at 1A each will generate in excess of 3W. Two PBSed vertically stacked stripes expanded laterally produces a very nice beam. You'll need a 2-3 power telescope to get a DPPS to match the divergence and you're cooling plan fits in nicely with this much more compact set up. I have worked with as many as 20 diodes in a module and the alignment is pretty tough. And remember if cooling; when one pesky diode gets a little out of alignment or focus (and that's another issue) then you have to warm it up, remove the enclosure, adjust and then replace the cover.

[taggalucci]

Guys, this is all great stuff honestly. But it's not helping this build!

[andy_con]

Guys, this is all great stuff honestly. But it's not helping this build!

what help do you need?

[taggalucci]

what help do you need?

Nothing right now unless someone has any advice with regards to "how to" with the parts I'm using or the design of the baseplate (which is really the only variable in this build).

My comment about help above was in regards to posts that described a completely different set of parts i.e. it's not helping me (my sanity or my pocket) basically suggesting I should ditch this set of very expensive parts and buy some more! I appreciate this was probably not the intent

I also appreciate that the posts may be of use to someone looking at this thread and thinking whether to buy similar parts to mine or go the alternative. However this is a build thread not a general "what's the best/cheapest/least-diode way to get 2+ watts of red" thread! Given many have lamented the lack of build threads, please lets try and stay on topic to help a builder out?

The comments regarding my choice of TECs and how these will be integrated into the plate were great and have challenged me to further consider the factors raised. They were discussed at length with a highly experienced industrial designer and I found his feedback on this enlightening.

I respect that Andy, Planters and others have already built multi diode set-ups, so I very much respect and appreciate your input. Please just don't tell me to chuck my parts in the bin and start over especially when these diodes can and have been combined successfully in the past! I.e. constructive contributions from the masters most welcome