LED questions

[bronk]

DealExtreme Web site is currently available. Here are the parts I used:

01920 23.36mm Optics/Light Diffusers for Cree Emitters (Glass/5-Pack) x 1 Shipped $5.54 -





04579 FUJIK Silicone Thermal Glue (50ml Grease-Like) x 1 Shipped $8.44 -
11922 3*Cree Reflector - Smooth Aluminium (18mm x 50mm) x 1 Shipped $6.90 -
15943 Cree XR-E R2 (WG) Emitter on Premium Star x 4 Shipped $6.99 - One LED was a spare - just in case

 

[rescue15]

Bronk,
If you had to buy the rest of the electronic parts, what would you have used for the current regulator and lamp dimmer? Are there any other parts I need to make the light work (other than the battery and switch)?

I have setteled into your configuration...the same reflector and 3 CREE XR E R2 LED's. I am going to use a Mag light for the head.

Steve

 

[Sailor612]

I'm on the same page...not much LED knowledge, but I just can't catch onto the LED tech talk either!! I started to make a 50W halogen can light, but after getting the light head done and seeing what it looked like; i started seeing info about LED's...

Bronk,
what would you have used for the current regulator and lamp dimmer?
Steve

Is this the same as the "driver?"
How do you use, or set up, a dimmer with a reed switch?
What do you attach the (3) cree's to? A metal plate/slug??

BRONK, your post has been helpful! Do you have your light complete? If so, how well does it penetrate water?

 

[willembad]

Here's what I built. It has been in a pressure pot (old paint spray-pot) to 7 ATA but I have not had the chance to dive with it. It is the same SSC P7/driver/reflector combo from DX and it is bright but I don't know what it looks like in the water.

If anyone is interested I can look up and post all the parts and suppliers that I used. Test battery is 8 18650 laptop cells in a 2s4p configuration - 7.4V/8Ah. Draw is 2.8A max according to driver specs but only tests around 2.2A, so not quite 4 hrs but close. Uses a reed switch to gate a mosfet for switching. You can see the elastic band around the light head that houses the magnet for the switch. On the pic that shows the reflector/emitter/driver you can see the fet and reed switch.

Hope it works as a dive light since I'm working on <@$200 including battery pack and charger.

Later,

Willem

 

[rescue15]

I like your canister Will. What did you use to make it. It looks alot nicer than the PVC pipe versions.

Steve

 

[willembad]

Those are polypro fittings - 2" cap, 2"x6" nipple and 2" x 3/4" NPT reducer from the Banjo fitting company. It has a 3/4" cable gland from McMaster-Carr in the top. he fittings was ~$6 a piece so less than $30 for can.

Willem

 

[bronk]

My first choice s to use a constant current source. A linear Constant Current LED Lamp Dimmer.
There are many modules prebuilt for 350mA or so, but none I could find for the 1A needed for the XR-E leds at max brightness.
So if you want something really simple you can go with a single resistor.
Assuming a NIMH 10 cell pack fully charged will give 12.6v.
3 LEDs will each have 3.4 to 3.7v forward voltage drop (per Cree spec sheet). I measuremed mine at 10.5v
12.6v-10.5v = 2.1 v drop. With a desired current of 1A this will requre a 2.1ohm resistor (3W or greater). With locally available (radio shack) components you might try 4 10 h 1W resistors in parallel which would give 2.5 ohms and 880mA.
Now as the battery runs down the brightness will drop so at 11.5v (maybe 2 hrs of run time) you will have: 11.5-10.5 = 1v 1v/2.5 ohms = 400mA. This means you will be down to a little under 1/2 original / peak brightness. Still not too bad, as te color will not change (unlike a regular light bulb). However with a constant current source the output will not have changed.

You can fine tune things a bit by measurming your set of LEDs. If your set comes in at maybe 11v instead of 10.5 like mine your could change your resistor. 12.6-11 = 1.6 v So with the same 10ohm resistors, 6 in parallel would give you 1.67 ohms and 950mA.

Remember start with a higher resistance and creep lower. Too much current and the magic smoke will come out and you will have $20 burnt offering to the electronics gods.

The reflector is bit large for a mag lite head. What are your plans for trimming it down?

 

[bronk]

One more option. I have not tried thse, but look very promising:
http://www.leddynamics.com/LuxDrive/datasheets/2008B-PowerPuck.pdf
They have a 1000mA (1 amp ) version . Roughly $15 and not other compenents . It states an "input margin" of 2v so with a 12v pack and 3 LEDs in series it s marginal , but fine if you doe a 11 or 12 cell pack (13.2 or 14.4v respectively.

 

[lil_mac]

View attachment 54468View attachment 54467View attachment 54466

Here's what I built. It has been in a pressure pot (old paint spray-pot) to 7 ATA but I have not had the chance to dive with it. It is the same SSC P7/driver/reflector combo from DX and it is bright but I don't know what it looks like in the water.

If anyone is interested I can look up and post all the parts and suppliers that I used. Test battery is 8 18650 laptop cells in a 2s4p configuration - 7.4V/8Ah. Draw is 2.8A max according to driver specs but only tests around 2.2A, so not quite 4 hrs but close. Uses a reed switch to gate a mosfet for switching. You can see the elastic band around the light head that houses the magnet for the switch. On the pic that shows the reflector/emitter/driver you can see the fet and reed switch.

Hope it works as a dive light since I'm working on <@$200 including battery pack and charger.

Later,

Willem

I would be interested in the parts and suppliers, and maybe how you waterproofed the light head.

Thanks

 

[ronscuba]

Has anyone looked into submersible lights for fountains ? I know they are probably not rated for use at depths we need, but maybe modify them some way ?

Here is site that has all kinds of interesting submersible LED lights for fountain use.

LED Light, Underwater Light Supplier And General Information