Hand Cranked Nichrome Ignitor

Discussion in 'The Projects Forum' started by jgsteeb, Mar 20, 2015.

  1. jgsteeb

    Thread Starter New Member

    Sep 7, 2014
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    I've been stuck on this problem for quite a while. I need to make a hand powered wick ignitor. Is it possible to take a hand powered generator, which can produce 200ma, hook it to a capacitor, charge the cap, then discharge across nichrome @ roughly 500 degrees F? Long enough to light a candle wick. I see it similarly to a hand crank flashlight except replace the LED's with a heating element.
     
  2. wayneh

    Expert

    Sep 9, 2010
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    Use a battery instead of a capacitor. It'll hold far more power in a smaller package and it will give you more steady and predictable power because its voltage stays more nearly constant while discharging.

    The flashlight may have circuitry to boost the voltage for the LED. You'll want to bypass that and heat your wire directly with the battery with nothing else in the circuit but the switch.

    Be aware that you'll have to crank for a long time to get enough juice.
     
  3. jgsteeb

    Thread Starter New Member

    Sep 7, 2014
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    Will I be able to recharge the battery by hand crank? I'm looking to create a circuit that has extreme longevity with no parts needing replacement. A survival tool in essence.
     
  4. alfacliff

    Well-Known Member

    Dec 13, 2013
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    I have a hand cranked radio, flashlight combo. it has a battery that is charged by the crank or a small solar cell. find one of these., it also has a usb connector for charging cell phones.
     
  5. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    What voltage do you measure when cranking out 200 mA?
    Have you tried igniting a wick with hot NiCr ?
     
  6. jgsteeb

    Thread Starter New Member

    Sep 7, 2014
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    ~12V, and yes I have ignited a wick with NiCr by creating a tight coil in which the wick inserts. Combustion occurred around 450°F so I figured ~500°F should be reasonable enough to allow quick ignition while conserving charge.
     
  7. wayneh

    Expert

    Sep 9, 2010
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    You can use a capacitor, which has some advantages in your application, but the problem is the amount of power you need. A capacitor large enough to heat your wire for a long enough time to light a wick, as it is losing voltage rapidly, is a "big" capacitor. I can't say much more without detail on the wire. Do you know what it draws?

    On the other hand it sounds like your crank might have enough power to light the wire all by itself without a storage device. 12V at 200mA is a fair amount. Have you tried that?
     
  8. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    Why nicrome? For more reliability and higher resistance to temperature, I'd suggest you take a look at tungsten carbide.
     
  9. wayneh

    Expert

    Sep 9, 2010
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    There was a thread here a few months back about the perfect wire for use in cutting machines. I don't recall the name of it but it might be ideal for this app also.
     
  10. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    I believe that it will work- saw the flash of flame & puff of smoke but wire opened prematurley. Wire- NiCr .005 dia, about 2.5 ohms/ in, a little fragile to work with altho have used it to cut foam. Seems that about 5 to 6 W needed, gen produces only 2.5 W. Test was with 2- 9V almost dead batteries charging a 37,000 uF & 30V cap. to 17V.
     
  11. wayneh

    Expert

    Sep 9, 2010
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    The wire I was thinking of is René 41.
     
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  12. Bernard

    AAC Fanatic!

    Aug 7, 2008
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    Finally lit candle with 1 in .005 NiCr with 1.2 A @ 3 V in about 3 sec. Wire did not survive. Rene 41 27 Ga looks good.
     
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