Recent content by PeterFH

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    Trying to build a Joule Thief

    Give me a day to get my components out of storage and ill take some pictures for you with a diagram.
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    Trying to build a Joule Thief

    You need a transformer, not two inductors, they both need to be coupled, that is way you driver is not working. Does it need to be a Joule thief? You get SMD led drivers that work way better then a joule thief and only need 1-3 additional external components. A Prema PR4401 for example...
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    Self Powering Flashlight!

    Sure, at least Texas Instruments sells a couple of energy harvesting chips, they all produce µA to very few mW of Power. The over all efficiency improvement that makes the most sense is a decent reflector. If you waste 20% of light in the reflector, that is a huge amount that you will never...
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    Self Powering Flashlight!

    Mono crystalline cells are more efficient *IF* they get above a certain amount of light input. At low light levels amorphous cells are more efficient. Without doing some further reading i would suspect amorphous cells to be better suited. But... where/how do you want to mount them and...
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    The first flashlight i ever build, a bit scruffy you might say.

    Just found this again while rummaging around the cupboard and thought you might get a chuckle out of this. http://imgur.com/a/VvHg0
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    Self Powering Flashlight!

    It does not matter much were you "inject" your harvested energy. At the moment, the simplest solution i could think of was the power source, because you do not need to worry about back feeding, potential differences, rectification and so forth. Just dump the power into the junction of...
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    Self Powering Flashlight!

    You could solve this in a number of ways, simple passive solutions (diodes and resistors) will kill your efficiency. And you need active regulation and maybe a switching regulator instead of a linear, again, you got to run your numbers! Simplest idea, on the top of my head: Single rechargeable...
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    Self Powering Flashlight!

    Tinkering and just trying out things is the best part about building something, you are right. Ignoring the fact that is not feasible because the math does not add up, lets have a look at it. If you have not clue how to do this, the best approach is to to start at the beginning. Order...
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    Self Powering Flashlight!

    From that viewpoint, it is very uninteresting. :) Looked up some numbers for a proper TEG module, the manufacturer says for it to work it should have 50°C on the hot side with a delta-t of 50°. That means, you would have to cool the other side of the TEG to 0°C while the flashlight is 50°C...
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    Self Powering Flashlight!

    A few months back i had idea for a TEG light as well and did some research. Normal peltier elements do not work well for this, special ones are expensive. Paralleling them is possible but not that good of an idea, forgot why though, would have to look into it again. After all that i ran...
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    Ordering metal core PCBs, what things to consider?

    Thanks for the reply! Yep, i am pretty much set on Seeedstudio. The 30 to 50 MPCBs i want to order will cost around 50 bucks, that is not too bad. Yep, was planing to use a PID controlled heatplate, solderpaste and hot air. I have a tiny bit experience with soldering small metal PCBs, i...
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    DIY LED reflector, how to design one?

    Thanks for the replys! After a bit of fiddling with foil, tape and thin aluminium sheet i came to the conclusion that it is far less critical then i thought. Pretty much anything shiny at a rough angle on the sides will do what i want. No need for a flawless finish, i want to make it...
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    Ordering metal core PCBs, what things to consider?

    Over the years, i have etched and build many PCBs, some at home, some i ordered in different parts of the world. The whole process with FR4 is not new to me, but i have never ordered MPCBs, but i have done some reading. Besides staying within the design rules of the PCB manufacturer, are there...
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    My fully custom 18650 Flashlight prototype with a 3D printed body.

    Thank you!
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    My fully custom 18650 Flashlight prototype with a 3D printed body.

    For the past days i have been doing some math and i have come up with some numbers, but before i say anything about them... Who would want to buy a Driver + Metal Core PCB + Nichia LED? It would be 90% assembled, you would have to solder in the switches and the battery/LED/sensor wires. A...
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