Re: One \'D\' Cell Luxeon Flashlight Mod
Hello Remuen, Thanks for your reply.
Regarding the current supplied to the Luxeon, through the MAX757, when I use a regulated power supply, at 1.2 volts in I can get 600mA input, and 360mA output at 3.2 volts. This tells me that there is some sort of limit on the current a alkaline or heavy duty 'D' cell can supply. Can a single alkaline 'D' cell supply 600mA current?
I ran the same test with a LM2621 evaluation board, with a fresh battery. This board is set for 5 volts. The output current was 190mA, at 3 volts. The LM2621, which is a factory made board with optimum design, coult not supply very much more than my regulator. This also tells me that at very best, with a very fresh 'D' cell (heavy duty or alkaline), we could get only 190mA. This is not very good.
The type of battery used here makes a difference. We are not using rechargable batteries, but disposable Alkalines, which cannot put out the current of the rechargables.
I did not use the more recent MAX757 board for this testing, with the lower resistance inductor, for it is already inside the flashlight. I used an older circuit I had.
In my latest design MAX757 step up regulator, I'm at 83% efficiency. I think with a home made inductor I might be able to get the efficiency up even more. However, the homemade inductor will be too big for the one inch disc.
I have a circuit design for the MAX756, which is a 1" X 2" board. It uses much less expensive components, and can use a hand would inductor. It costs me about half as much to make this version (under $10), and it is suitable for a 'D' or 'C' cell dummy.
Remember, the MAX757 regulator has variable voltage, and I can set it to 4 volts for Nichia's.
Wayne
ElektroLumens.com