3500 PAR DIY LED Cannon

[Timfish]

These are instruction for a DIY cannon I designed after having to come up with a lighting solution for this system that required recessed lighting in a balcony ceiling over 5' above the tank. Dana Riddle evaluated the cannon for spectrum, wattage and PAR and his results are in the xlsx file. The pdf instructions assume someone with basic "lob a blob" soldering skills and a basic understanding of electrical circuits. The xlsx document has spectral output, wattage and PAR map @ 9".

 

[lapin]

Nice

 

[Timfish]

Bump

 

[keepingfishwithnoidea]

Nice project, doing something similar.

 

[Timfish]

Thank you! It's a simple design that can be repeated to get really high PAR numbers. For this system I used three fixtures with 26 of the LED stars on a single large heatsink to get 500 PAR with the fixtures mounted 5' above the tank. It seems like it might get complicated but since it's just 2 LED stars in series with a Luxdrive bucpuck driver which have a common ground so the heatsink can be used as a ground for everything, so it's just a three component series circuit repeated as many times as necessary. If you want to make it complicated you can use drivers that require the LEDs to have isolated grounds and if you really want to make it complicated you can use drivers with dimming to dim each series circuit individually. ;)

 

[vandy]

What was the total cost? I made a couple 100w cannons and I'm in around $50 per light. They are ****** Chinese COBs tho

 

[oreo54]

Bump

Why JB weld?.. It's not very good for thermal transfer.
Things like "heatsink plaster" are silicone "glues" with better heat transfer properties.

It's not a particularly good thermal conductor as epoxies go, there are purpose-made thermal epoxies that can achieve thermal conductivity in excess of 3.0 W/Mk, where JB weld is more like 0.3, and standard un-filled epoxy is more like 0.15.

Amazon product ASIN B072MSXHJD

G109 10gram Thermal Conductive Glue​

• It has good thermal conductivity and wide service temperature range(-60~280 degrees Celsius)
• Thermal conductivity:> 1.5W/m-K

 

[Timfish]

What was the total cost? I made a couple 100w cannons and I'm in around $50 per light. They are ****** Chinese COBs tho

Certainly! I've messed with them and super bright light levels can be achieved cheaply and inexpensively. I was never happy with the spectral output. Using Cree LEDs on stars gives me a better spectral output. I also prefer the redundancy provided with muliple parallel circuits.

 

[Timfish]

Why JB weld?.. It's not very good for thermal transfer.
Things like "heatsink plaster" are silicone "glues" with better heat transfer properties.


Amazon product ASIN B072MSXHJD

G109 10gram Thermal Conductive Glue​

Yup, you are correct, they certainly are. Simple reason is JB Weld is cheap and does the job (JB Weld is about 40% steel even though it's classed as an insulator). Tests on how hot these fixtures get after they've been running awhile showed the aluminum stars and the discs they glued to were varied by the different designs we tried but stayed well below 120º F.

 

[oreo54]

Yup, you are correct, they certainly are. Simple reason is JB Weld is cheap and does the job (JB Weld is about 40% steel even though it's classed as an insulator). Tests on how hot these fixtures get after they've been running awhile showed the aluminum stars and the discs they glued to were varied by the different designs we tried but stayed well below 120º F.

At 10x more efficient in thermal transfer and $10 for 30g I'll stick to thermal silicone . You barely need much per star. ;)

 

[Timfish]

At 10x more efficient in thermal transfer and $10 for 30g I'll stick to thermal silicone . You barely need much per star. ;)

(Although from what I've been able to ascertain, Easycargo ES910 is only roughly 30% more thermally conductive, .975 w/mK vs .7 w/mK. Not 10X.)

 

[oreo54]

(Although from what I've been able to ascertain, Easycargo ES910 is only roughly 30% more thermally conductive, .975 w/mK vs .7 w/mK. Not 10X.)

Well initially my search returned much lower numbers than the .7 above.
There is enough circumstantial evidence as to it real world effectiveness which is to be frank better than I initially believed.

Taking all the properties differences dedicated thermal silicone adhesive have no real weakness in comparison to jb weld.
Not even price really.
It is cheap (JB) as to 2 part epoxy substances go.
But things like arctic silver are vanity substances or like 1 time use type stuff IMHO And frankly not near as strong as they say. I started with 2 part as in builds and was amazed that when my first cheap eBay stars failed it was relatively easy to remove epoxied stars. As easy as removing silicone stars.
Btw " my" thermal silicone of choice is selling for under a dollar for 60g. .8-ish

5 pack 60g each..
Under $10..
Actually $3.45/5 pack of 60g tubes.. 0.8
Crazy..

For a bit more one can get much better than .9


AI's a bit harsh on it.

JB Weld's thermal conductivity is significantly lower than that of thermal pastes and it can also be electrically conductive, posing a risk of short circuits.

And my initial number was taken from something like this...

there are purpose-made thermal epoxies that can achieve thermal conductivity in excess of 3.0 W/M-k, where JB weld is more like 0.3, and standard un-filled epoxy is more like 0.15.

Now I'm curious as to "real" numbers for which jb weld.

So I stand corrected with a caveat.. :)

Just for fun and the last time I actually did some research to better the heat transfer I started looking into "sheet goods" since I was frustrated by the slow dry time of the Tian Mu thermal silicone I was using.
And also to improve the transfer number.
Technically it was sort of "my" jb weld. Cheap adequate.. ect.

I found it was (is) fairly easy to find better 2 sided self stick sheets than affordable tubes of high transfer thermal silicone.
Like this which is roughly 3x better than jb weld.
Pad is 93 sq inches which would roughly be for 93 star boards.
$36.13
Adds 40 cents extra per star.
https://us.rs-online.com/product/rs...0vpPe6fx5SjN9JGSNNcClQdWkm0sDRDOH3YSyVLKEbrqc
So there are relatively affordable options..

 

[Timfish]

Well initially my search returned much lower numbers than the .7 above.
There is enough circumstantial evidence as to it real world effectiveness which is to be frank better than I initially believed.

Taking all the properties differences dedicated thermal silicone adhesive have no real weakness in comparison to jb weld.
Not even price really.
It is cheap (JB) as to 2 part epoxy substances go.
But things like arctic silver are vanity substances or like 1 time use type stuff IMHO And frankly not near as strong as they say. I started with 2 part as in builds and was amazed that when my first cheap eBay stars failed it was relatively easy to remove epoxied stars. As easy as removing silicone stars.
Btw " my" thermal silicone of choice is selling for under a dollar for 60g. .8-ish

5 pack 60g each..
Under $10..
Actually $3.45/5 pack of 60g tubes.. 0.8
Crazy..

For a bit more one can get much better than .9


AI's a bit harsh on it.



And my initial number was taken from something like this...


Now I'm curious as to "real" numbers for which jb weld.

So I stand corrected with a caveat.. :)

Just for fun and the last time I actually did some research to better the heat transfer I started looking into "sheet goods" since I was frustrated by the slow dry time of the Tian Mu thermal silicone I was using.
And also to improve the transfer number.
Technically it was sort of "my" jb weld. Cheap adequate.. ect.

I found it was (is) fairly easy to find better 2 sided self stick sheets than affordable tubes of high transfer thermal silicone.
Like this which is roughly 3x better than jb weld.
Pad is 93 sq inches which would roughly be for 93 star boards.
$36.13
Adds 40 cents extra per star.
https://us.rs-online.com/product/rs...0vpPe6fx5SjN9JGSNNcClQdWkm0sDRDOH3YSyVLKEbrqc
So there are relatively affordable options..

This is the paper that looked at JB Weld's thermal conductivity and gave .747 w/mk.

I experimented with multiple methods back in the mid 2010's. They all worked. By far the cheapest was generic aquarium silicone (~$7 for 283 grams). What I didn't like about it, like you, is how long I had to wait for the silicone to set up so the stars wouldn't slide around before soldering leads to them. JB Weld Qwik provided the fastest build time at a very good price point. I was not impressed with adhesive stars at all, between trying to peel them off, stick them to a LED star and set them perfectly in place it took a lot more time than gluing them in place. The method I liked the best, as it was easy to replace starsif needed, was drilling holes and using #2 screws and thermal paste, but assembly time was too long. With JB Weld Qwik it takes just a few minutes to mount 7 stars and the jig for holding the lenses onto an aluminum disc and adhere that to a heatsink then start prepping wires and by the time the wires are ready to solder to the stars I don't have to worry about them sliding around.