[PSUBS-MAILIST] LED Light test

Fri Mar 10 20:35:05 EST 2017

Thanks Alan, luckily I don't follow rugby... ;)
(or whatever variant that is!)

Cheers
Steve

On Fri, Mar 10, 2017 at 5:35 PM, Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Hi Steve,
> here's my contacts email if you get interested.
> kevin at tyf-led.com
> Great person to deal with, & if you say "sample" you
> can buy small quantities. I bought mine initially without the pigtails
> but got them to solder them on for 50c each, as they needed a lot
> higher watt soldering iron than I had, & also I didn't want to overheat &
> destroy
> any in the soldering process.
> It's pouring down in Auckland & the Warriors are taking on your Melbourne
> storm
> in half an hour. Going to be a messy game.
> Alan
> Sent from my iPad
>
> On 10/03/2017, at 4:22 PM, Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Thanks Alan, your LED flip chip is quite interesting - my research has
> only been into much smaller LEDs (CREE XML2) and it's cool to see such a
> big one!  Pretty hard to argue with $6.50 too.
>
> Cheers,
> Steve
>
> On Thu, Mar 9, 2017 at 8:40 PM, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Thanks Steve,
>> that's great to know about the heat on the acrylic lens & your testing.
>> At the moment I am driving my lights with a buck / boost constant current
>> driver
>> that has a 60V input for my 48V system. It took a lot of work tracking
>> down a
>> unit that was suitable for 48V.
>> A friend put me on to those linear regulators & is trying to convince me
>> to go
>> with them. I will keep your information in mind should I need to argue my
>> way
>> out of them.  They would be good for a Sub on a 36 V system, as most of
>> the
>> high power LEDs are 36V.
>> Have a look at the flip chip LED I'm using if you haven't already seen it.
>> Smaller than the usual cob LEDs.
>> http://www.tyf-led.com/downloadRepository/82befdc2-15b3-
>> 4ff0-a553-6f53a4d8e404.pdf
>> Got mine with pigtails on for $6:50- each.
>> Cheers Alan
>>
>>
>>
>> Sent from my iPad
>>
>> On 9/03/2017, at 9:54 PM, Stephen Fordyce via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Hi Alan,
>> I'm glad your lights are going well!  There are a couple of things I may
>> be able to contribute after several iterations of designing the circuit for
>> my TFM caving/diving helmet lights.
>>
>> *1. Linear vs switching LED drivers.  *
>> I looked at the datasheet for your LED driver chip and it appears to be a
>> linear regulator - this in general terms means it creates a variable
>> resistance to get the output current/voltage right, and as such can create
>> a lot of heat which may be wasteful.  Ie. if you have a 12V supply and your
>> LED needs 4V, 67% of the power will be lost in the driver!  But if you have
>> a 12V supply and your LED chain needs 11.5V, then it's quite efficient.
>> They are simple and easy, and small as you point out, with no external
>> components.
>>
>> A switching driver uses very fast (MHz) PWM along with an external
>> capacitor/inductor to drop and smooth out the voltage, and is ~90+%
>> efficient over a big range of voltage drops.  This means it creates much
>> less heat and saves power.
>>
>> I changed to switching drivers for my LEDS (input 7-8V, output 3-4V) and
>> noticed a huge difference in heat and efficiency.  Just something to be
>> aware of if you run into heat or runtime problems.
>>
>> *2. Acrylic windows*
>> I have used lasercut acrylic (6mm) in my caving lights (which I've had up
>> to 80degC according to the internal temp sensor.  Lasercutting allows me to
>> get an oblong rectangular shape with holts for screws.  The lights have a
>> full high temperature burn test out of the water and then multiple dives to
>> 100m in my pressure pot, with no acrylic failures to date.
>>
>> Cheers,
>> Steve Fordyce
>>
>> On Thu, Mar 9, 2017 at 6:12 PM, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Tested my 80W LED light in a housing, to see how hot it got in & out
>>> of the water.
>>> The good news was it didn't get warm at all after running at 70W for
>>> 25 minutes in the kitchen sink. Out of the water it hit 120F (49C) in 7
>>> minutes. The LED has a maximum temperature rating of 60C so was keeping
>>> back a bit from that.
>>> I dropped the current down & ran it out of the water at 33W & 25W but it
>>> climbed
>>> to 125F in 20 minutes for 33W & 15 minutes for the 25W.
>>> I am using a cast acrylic 8mm thick lens, & this didn't get hot either
>>> in air
>>> or water. Using acrylic instead of glass is saving me $90-.
>>> Am making a few minor housing design adjustments for the final iteration.
>>> Have also ordered a dozen of these 50 V 350 mA constant current
>>> regulator &
>>> LED drivers.
>>>
>>> http://www.onsemi.com/PowerSolutions/product.do?id=NSI50350AD
>>> They are TINY; about 1/4" square & you run them in series to get the
>>> desired
>>> amperage. They have a wide input voltage & would be great for a 36V
>>> system.
>>> Alan
>>>
>>>
>>> Sent from my iPad
>>>
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>>>
>>>
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