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DiveTorch Update

16 Sep 2011
Its been a while since my last update due to lots of other ongoing work. However progress is being made with the torch. Firstly some problems, then some progress.

I discovered the LM2733 Boost convertor was nowhere near beefy enough to drive 45V at any kind of power so this has lead to the abandoning of the CREE 45V LED and instead ive designed in a more suitable 12V Bridgelux. The change will result in a less powerful torch but after much consideration i decided that the point of the project was to experiment with switch output underwater and not to make the most powerful torch possible.

See the Pictures below for LED's side by side.

Unknownname

Next big change is my decision to swap the PIC16F for a PIC24F, with a smaller package and less pins the PIC24F will save some space on my board although this isnt the main reason for this change. The PIC16F used a Hi-Tech compiler to compile my C code to the apropriate asembly languare for my uC. The PIC24F uses Microchips C30 compiler which has a much bigger development community and support network available. Hopefully this will be useful in the future as i look to increase the complexity of my torch i can leverage some pre written open source code.

Lastly but by no means least ive connected the LED to the uC via a IRLL024 MOSFET. This MOSFET should handle fast switching of 1A easily (see graph below) with a Vgs ~2.7V. This Choice also provides possibilities for higher current switching with some redesign of the project.

0unknownname

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