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3Instructables125,067Views23CommentsJoined March 8th, 2009
Currently, I'm at a startup trying to change the world. In previous lives, I was an EE Prof., an Imagineer at Disney, and, according to Jay Leno, "a Japanese scientist" (I'm not Japanese, or a scientist). In academic circles, I'm best known for DiamondTouch, one of the early multitouch systems. In the DIY community, I'm probably best known for the bidirectional LED trick and teaching kids how to build animatronic shows. To the general pubic, my most famous (infamous?) projects are iGlassware... Read More »

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  • An LED You Can Blow Out Like a Candle!

    Thanks for asking! I would appreciate the attribution and a pointer back to this original Instructable. But you should feel free to build on this - it's kind of the point of making it public! I'd also ask you to post a link to your Instructable here, so others looking for inspiration can find your work easily.

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  • An LED You Can Blow Out Like a Candle!

    I haven't tried 1.8mm LEDs, but my guess is that they would not work well for this application. Because of the way these are molded, I would expect the thermal time constants to be annoyingly long.

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  • An LED You Can Blow Out Like a Candle!

    The noise might be coming from your power supply. Try using a cleaner supply (like a battery), and see if that helps...

    A few things to check come to mind. First, do you have the 3.3V or 5V version of the Pro Mini? If you have the 3.3V one, you will need to use a smaller resistor to get the requisite current. The 3.3V version is also slower, so you may need to change some of the timing. It looks like your LED is touching the table, which could steal heat away. You can always make MINJUMP so large that it never triggers. Then you can watch the plot to see exactly what's going on without the switching confusing things. Since you have a working UNO version, I'd compare the plots from the two versions. That might give you a better idea what's going on. Finally, I'd double check the resistor value to make sure it's 200 ohms and not 2k. (I could tell from the pic)Good luck!

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  • An LED You Can Blow Out Like a Candle!

    Yes, I think it should work just fine. Apparently, the Due, Zero and MKR family Arduinos have 12 bit ADCs rather than 10, so you may not need to do any averaging with those...

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  • An LED You Can Blow Out Like a Candle!

    You might see that amount of change as the LED goes from cold start to warm. It depends on your LED and resistor value. However, if you just have the LED on, the curve should be pretty smooth in still air. I'd suggest setting MINJUMP to something very large so the LED never goes out, and then just look at the plot to see what's happening. If you are still seeing a lot of noise, my next suspect would be a noisy power supply. If you are on a laptop, try running from battery and see if it makes a difference.

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  • An LED You Can Blow Out Like a Candle!

    Unfortunately, that's harder to do because to make the measurement you need to turn on the LED so it can get warm allowing the wind to cool it down...

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  • electron_plumber's instructable An LED You Can Blow Out Like a Candle!'s weekly stats: 2 months ago
    • An LED You Can Blow Out Like a Candle!
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  • An LED You Can Blow Out Like a Candle!

    You can certainly use an LED to sense light from another LED, so, yes, that's easy to do. The simpler method is to do it with a single LED, detecting the initial match, and just staying on after that. (You have a micro controller, so logic is easy...)The SIGGRAPH workshop I just did also covered the old bidirectional (emit and sense) LED tricks we developed at MERL 15 years ago:http://www.merl.com/publications/TR2003-35The SIGGRAPH workshop materials include info/code on doing simple bidirectional LED things on Arduino:https://github.com/paulhdietz/LEDSensorsEnjoy!

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  • An LED You Can Blow Out Like a Candle!

    A silicon diode will drop around 0.6 - 0.7V. If you don't need to turn it on and off, you're not limited to the current an I/O pin can provide. So the resistor will depend on the how hot you are willing to let the device get. Hotter will generally work better. Definitely get one in a small package - a sot23 or smaller - and use thin wires. Also, because the voltage drop is so low, you can use the internal reference voltage on the ADC to set a smaller full scale, which will give you more resolution.

    It's here in these comments, but here it is again:https://github.com/paulhdietz/LEDSensors

    You should be able to easily measure the change. Here's a link to a nice presentation on LEDs from On Semi, and I direct you to page 12 which discusses the temperature characteristics of different LEDs:https://www.onsemi.com/pub/Collateral/TND328-D.PDF

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  • An LED You Can Blow Out Like a Candle!

    Indeed! It was an article he wrote in the 1970's that explained how to use an LED as a photodiode that got me started playing with stuff like this...

    I just add that automatically to code and really didn't think about it. If you look on github, I released it under the MIT license...

    The MIT LicenseCopyright (c) 2010-2018 Google, Inc. http://angularjs.orgPermission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions:The above copyright notice and this permission notice shall be included inall copies or substantial portions of the Software.THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS...

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    The MIT LicenseCopyright (c) 2010-2018 Google, Inc. http://angularjs.orgPermission is hereby granted, free of charge, to any person obtaining a copyof this software and associated documentation files (the "Software"), to dealin the Software without restriction, including without limitation the rightsto use, copy, modify, merge, publish, distribute, sublicense, and/or sellcopies of the Software, and to permit persons to whom the Software isfurnished to do so, subject to the following conditions:The above copyright notice and this permission notice shall be included inall copies or substantial portions of the Software.THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS ORIMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THEAUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHERLIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS INTHE SOFTWARE.

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  • An LED You Can Blow Out Like a Candle!

    Thanks for coming to the SIGGRAPH workshop! I've posted the class materials at:https://github.com/paulhdietz/LEDSensorsThe class covered more stuff (including the old LED as a light sensor tricks), so if people want to dig a bit deeper, they can look at the slides and the sample programs...

    Most resistors are designed to have minimal change with temperature - typically 100's of parts per million per degree C or less. So it would be difficult to measure. It's also not well controlled. You can buy resistors that are specifically designed to have specified PTC or NTC (positive or negative temperature coefficients), but they aren't quite as common as LEDs. But those can certainly be made to work. You can also use regular silicon diodes, which should work similarly.

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  • electron_plumber followed CathyDietz4 months ago
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