DIY LED lamp

[odessa.dk]

Hi Pack
cannister is 35cm x 10cm will sit on my Air tank. yes i will have 2 Maglite. I can have bought turned on Max power four 2 dives ( 2 x 40 min ) or I can just take one with me down, it's more what kind of light I need, one of them I can use to take picture with, and the other I can use to long distance, give me some time, I still need three more weeks before i'm finish with it.

 

[jbcpok]

Odessa, would love to see some pictures of it when your done, keep us updated!

 

[odessa.dk]

The only picture i have is this.I have use 3 Fraen reflector for Cree XR-E 7` after i have fix them to P7 i think it is a 45 ` the pic you see here is 2 M from the wall 2.8 A. Volt is 10.3

I still need to test it out, but the wheter is not the best right now, there is to much strong drift.
I hope this weekend i can test it out down to 40 meters. My next mag i'm still waiting for they are going to release some new reflecters, i hope in november, they will be out for P7. - MC-E Led.

 

[BHB ScubaTroll]

OK, I'm new to designing my own can light.

Some would call me a troubleshooter of sorts (not with electrical, so this will be a great learning experience)

Here's my first question... Why are most projects starting with the existing light that is not designed for underwater use?

I must have 7-10 underwater lights that already start out water resistant.

There seem to be a number of underwater lights that fit the bill for water resistance when you begin to look at LED solutions.

For some perspective, I just took out my maglight and with slight modification to the reflector, it fits into my Ikelite mini C housing (Yes, the heat sink will take a bit of thought, but the water resistance is already there

 

[Packhorse]

Plastic is a heat insulator not a heat conductor so a plastic light head makes it hard to get the heat out of the head.
Mags are fairly cheap too and easy to make water proof. They also allow for a large (50mm) reflector which means a tighter beam or more space for LED's.

 

[350xfire]

Packhorse:
I have a ?? for you. I have been playing around with my variable power supply rated at 18 volts and 3 amps. If I run a P7 with not driver, I can run it a 3.6 volts and it will pull 3 amps. I can take the power supply and run it all the way up and the LED will not pull more than that, no matter how much I try to push into it. So, questions, will an LED regulate itself? It seems like the P7 does. Also, what is the negative of running direct drive? In my opinion, it is best to run direct since the LED runs at a much lower voltage. Using a driver takes about 5 volts to achive 3 amps.

Just some observations. I can run 3 P7 in series at about 10.6 volts with no driver. Pretty impressive lighting too. I was thinking about running 9 NiMh "D" at 10.8 volts for 3 P7. Of course, I'll need a hell of a heatsink. I am going to buy a lathe soon and play with some custom spun torches.

 

[Packhorse]

The more voltage you put into it the more current it should consume untill "POOFFF" the magic smoke comes out. And with out the magic smoke inside the LED will not work. Not sure how much voltage you pumped into it but did you measure it at the LED? It will not self regulate! You may need to put 5volt into the driver but it will probably put out alot less. What driver?

Sure you could direct drive 3 P7's on 9 NiMh no problem. Until you put a freshly charged batter pack in and it puts out 13 volt and fry's the LED's. Way better off getting 2.8amps worth of AMC 7135 drivers on the first P7 and series the other 2 with the driver. There is a thread on CPF on how to do this, but the single driver must suckup all the excess voltage.

Go the Lathe!! so much fun. Just remember to allow for the cost of tools. Can be as much as the lathe or more.

 

[350xfire]

Thanks Pack.
I saw your finned mag lite on the SODS forum. I assume you got a lathe. What size did you get? Have you done anything cool yet? Yes, I was looking at either a 7x12 or 8x12 from Harbor Freight and you are right. By the time you get the stand and the tooling, the lathe becomes much much more expensive. That's the price we pay to play...


As far as the LED, yes, I did some measuring after the driver and you are right. The driver does lower the 5 volts down to about 3.5. My deal is that if I direct drive, I can use a lot smaller (cheaper) battery pack with smaller can. I am direct driving 2 Mag conversions with 3 Alklines at 4.5 volts and they are running great. I figure NiMH run at 1.2 so 3.6 (plus over charge) so I should be able to easily direct drive with NiMH using 9 D batteries at 10.8 volts. Even if the 10.8 goes up to 13, the excess voltage will be split amonst 3 LEDs. I would not think less than one volt would be a problem, do you? So bottom line, this is what I gain from direct driving--- use smaller battery pack and keep things simple by not using driver.

Now, if I use 1 driver and it takes the excess voltage, I would have to build a hell of a heatsink for it, right?

 

[Packhorse]

My lathe is a Sherline lathe. 3x8inch I think. Its a great little lathe with the emphasis on little.

You say its only 1 volt or so but when you are talking LED's with a Vf of 3.7v 1 volt is a 30% increase in voltage and probably alot more in current. For the small cost of a 7135 style driver why risk blowing up $75+ worth of LEDs?????

The driver will not produce as much heat as the LEDs. I just mount the driver on the back of the LED heatsink like these....

 

[Packhorse]

Ooop double post.