Recent content by bulrush

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    Sold/Expired More Joule Thief lights available

    I stilll have some of these available.
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    Lithium battery shipping

    us.banggood.com ships from a US warehouse, but they don't have as large a selection as their China warehouse.
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    costco eneloops model number is unusual

    I have to play the Devil's Advocate here. Sometimes a mfr will make a deal with a retailer, like Costco, and make a similar product of inferior quality. But they have to modify the model number so the mfr knows who to ship that particular item to. This is very common for Black Friday products...
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    Poland builds a solar-powered bike path that glows a ghostly blue

    There's a form of calcite that glows blue after being charged by the sun. I wonder if they put that in the cement. Youtube video here.
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    What's the brightest glow-in-the-dark stuff

    I have some with the strontium-europium compound. You have to charge it up with bright light and it will glow very well for 4 hours, then the last 4 hours it's still visible but gets more faint as time goes on. I've heard it called the "2nd generation" GID powder. I have a 1oz packet which I...
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    Tritium replacement?

    Curing glue with UV usually requires a very specific wavelength of UV light. Check the tube of Norland for the requirement, then check the output wavelength of the UV light you bought. The wavelength will be in nanometers (nm). If the difference between what the Norland glue requires and the UV...
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    Custom red light

    I've made a few flashlights but 1. I don't know if any red LED will light up their eyes at 500 yards. Do you know for a fact that their retinas actually reflect red light? 2. I've never seen a red LED with a lot of "throw" distance anyway. 3. But the circuit is easy to build anyway. I myself...
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    How does a 3.7v 18650 provide 5 volts ???

    The device should use a voltage booster to boost the voltage to 5.0vdc. The USB spec requires the USB port to output 5vdc, or the voltage booster part is broken. Ebay sells charging boards that charge 3.7v lithium batteries, and has a USB port that also outputs 5.0vdc. So it's a charging card...
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    Flashlight Powered by Peltier Junction and Body Heat

    There's another guy on Kickstarter who is making an LED flashlight that runs on body heat. The aluminum, block body acts as a heat sink for the cool side of the Peltier device. However, the voltage made by the Peltier is directly proportional to the temperature difference. That means, in 90F...
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    12v, 23 amp battery, what is it used for?

    I found this 12v 23a battery. It's smallish and might work for an LED flashlight. But what the heck are these normally used for? Is this for real? The model appears to be L1028F. Sold by a guy in France in retail packaging, so apparently they are made in bulk. And how can it be so cheap and...
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    Best coin pocket LED flashlight

    I have had a Microlight for 15+ years and it works fine. I just change the battery about every 5 years.
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    Led burnout

    If too much voltage gets to the LED itself the voltage will fry the LED. If the LED driver board accepts 3-9vdc and you gave it 12vdc, then too much voltage probably got to the LED and either fried the LED, or a driver component. I've fried a few LEDs myself directly connected to a battery...
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    Sold/Expired More Joule Thief lights available

    I still have Joule Thief lights available for $9usd. And a box light that has a high, and moonlight mode, which uses very little power to help you find the light in the dark while camping, during a power outage, etc. Have a look and see what you think. https://goo.gl/5tqVSO
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    Sold/Expired WTS: LED flashlights that use "dead" batteries

    Which LED flashlights take 0.9vdc as input? I might want one. My light was shining with just an input of 0.3vdc, although you could not use it to read. It was more of a marker light.
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    Sold/Expired WTS: LED flashlights that use "dead" batteries

    Yes, it really works! I thought it was a fun idea! I'm just a hobbyist but I have an Etsy store. There is an 1AA model and 2AA model. It squeezes out the last bit of juice from your "dead" AA cells to give you light in an emergency. When the AA battery won't work in other devices, it will work...
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