[PSUBS-MAILIST] PWM LED driver for Cliff's enclosure

Sat Apr 22 09:31:59 EDT 2017

I'm still planning on making a second set of lights and so will machine the
enclosure. My first set is 5K, but the next one is 10K. Now having said
that I already have the driver for it, but am happy to test the proposed
one. Ah, and my existing driver lacks dimming so this would also be a plus.

Best,

Alec

On Sat, Apr 22, 2017 at 8:29 AM, Cliff Redus via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> River, thanks for picking up the ball on the LED driver PCB for the Psub
> 10k light.  I support everthing you have said but do agree with Alan on the
> supply voltage range.  A lot of the PSub community use a 36VDC main bus to
> drive the Minn Kota 101's for thursters.  The expected voltage range for
> three 12V batteries in series is on the order of 30-40 volts so 36V max on
> the LT3478 is not going to work.  See specification of this supply voltage
> in the 10K LED project speciation page I sent you.  Also, you will need to
> change the pin out in the Psub spec. as well as the part number for the
> Subconn connector to be able to have diming via a 0-5 VDC analog control
> signal.
>
> For simplicity and KISS, I think we should abandon the optional side mount
> on the enclosure drawings I developed and just focus on the rear entry for
> the bulkhead connector.  Due to the delay in getting a viable driver for
> the 10K LED project, a lot of folks have gone their own way on external
> lights.  We are going to have to get someone that still needs external
> lights to machine the prototype enclosure.   I am willing to test the
> prototype light in my test chamber.
>
>
> Cliff
>
> On Sat, Apr 22, 2017 at 12:03 AM, River Dolfi via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Hey everyone,
>> I've managed to convince a professor at the University to let me tackle
>> developing a high power LED driver for psubs purposes for a grade. I'm just
>> curious which features everyone would like in an LED driver. I am designing
>> a driver for the Bridgelux Vero 29 LED array and will hopefully package it
>> into a form factor so that all of the electronics fit into the enclosures
>> Cliff designed and presented at the last convention.
>>
>> So far I plan on using a small microcontroller (probably an ATTiny for
>> those who are interested) to generate a PWM signal that will switch a
>> MOSFET, to control the amount of power delivered from an off the shelf
>> constant current LED driver chip. The chip I found, the LT3478, seems to be
>> ideal for PSUBS purposes, as it contains it's own converter that will
>> accepts anything between 5 and 36 volts.
>>
>> I'm also probably going to incorporate a temperature sensor that will
>> shut the light down if it gets too hot (running the light for too long out
>> of the water) and killing the electronics/melting the lens. The
>> microcontroller will accept a 0-5 volt analog signal from either a
>> potentiometer or a PLC in order to convert that to a PWM signall to dim the
>> lights.
>>
>> Are there any major features that I'm missing? It seems that PWM dimming
>> and application specific temperature control are the big ones. Curious to
>> get input from those that are running LED rigs right now.
>>
>> --
>> -River J. Dolfi
>>
>> 412-997-2526 <(412)%20997-2526>
>> rdolfi7 at gmail.com
>> rwd5301 at psu.edu
>>
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>>
>>
>
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