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Electric heating element

Discussion in 'General Electronics Discussion' started by jan019, Mar 14, 2011.

  1. jan019

    jan019

    7
    0
    Mar 14, 2011
    Hello,

    I'm new to this forum and am an absolute noob in electrical stuff. As you see from the title of this thread i would like to make a heating element. Not anything complex, just any easy wire shaped into a coil and it should heat, BUT i have no idea how do it. I would like to use some sort of wire in diameter probably about 2 mm and i would like it to be able to give of about 500ºC or more. But first i would make a prototype with using a simple 9V battery. I just need to know how could it be made. If I can only plug one end of the wire to one pole of the battery and the other end to the opposite pole and it would heat or if i would have to put some resistors after the heating wire in the circuit so that the battery doesn't blow up. I know that some things I said might be hard to understand and maybe even unconstructable, but please help me. Also how much ºC do you think the 9V battery might give? I know it depends on the resistance of the wire so just give me any example of wire diameter and how much heat would a 9V battery produce. Thanks
     
  2. Resqueline

    Resqueline

    2,848
    1
    Jul 31, 2009
    A 9V battery easily gives 3000 ºC or more, in a light bulb. So I just ask, what significance does the temperature have?
    An alkaline 9V battery contains up to 0,5Ah which translates to 4.5Wh or 16200 Joules. So, what do you really want to achieve with this energy?
    Such batteries don't like to be emptied very fast, so you won't be able to extract anywhere near 4.5W for a duration of anywhere near one hour.
    The resistance, strength, & melting points of different metals vary greatly, creating very different solutions. What resources do you have at your disposal?
    Anyway, for a 9V battery you'll be looking for as thin wire as you can get; 0.1mm, regardless of material.
    A 2mm heater wire is industrial scale. What kind of power source did you have in mind for driving this, and how will you handle the support and the heat?
    In my younger days I once made a heater element rated at 12V & 120W(?) out of a section of an old mains water heater. It was 5cm wide & 7 cm tall and ran red-hot.
     
  3. jan019

    jan019

    7
    0
    Mar 14, 2011
    Hi,

    Thanks for the reply. OK forget about the 2 mm wire, I will try to do it with the 9V battery and a 0,1 mm wire.
    Well I do have a 0,1 mm wire and I do have a 9V battery, so how much ºC do you think I could get out of it? I would use the heater for lighting up a hookah coal, the coal has a cube shape, so i would want "wrap" the wire around it and light it up(the coal can be lighted by a coil burner, but i would like to make a heating element for lighting it by myself).
    So if it could be made, how? By connecting the wire directly to both poles of the battery? Wouldn't the battery explode or something? And how long could the battery last for one go? Also what do you mean by "Such batteries don't like to be emptied very fast." I just donno what you mean.

    John
     
  4. davenn

    davenn Moderator

    13,212
    1,730
    Sep 5, 2009
    well you are basically wanting to short out the terminals of the battery with the heating coil wire.... its going to have very low resistance hence hi current flow thats what most batteries dont like, its going to get very hot in its short life. Chemical reaction batteries like your AA, AAA, small 9V etc cant handle fast hi current discharge
    Any very thin wire between the battery terminals is probably just act like a fuse and almost instantly burn out.
    altho I havent played with for a long time, you could see if you could still get some nichrome wire, it has a set resistance / metre (foot).

    powering this coil from a battery is probably not the way to go, unless you have a big bank account to be buying lots of batteries. It would probably be more successful by using a hi current and current limited power supply where you could at least control the current flow and experiment.

    failing finding nichrome wire, you could try a short length of the wire from an old wire wound bar heater. remember those ? many turns of wire on a creamic core ?

    Dave
     
    Last edited: Mar 20, 2011
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,171
    2,687
    Jan 21, 2010
    If I was going to do this with a battery, I would be more inclined to go with a D size 1.5V battery.

    How long would it last? That depends entirely on the current. And that depends on the type and length of the wire. And that depends on how hot you want it to get and how much current you can draw from the battery.

    Yes, I know that goes in circles.
     
  6. jan019

    jan019

    7
    0
    Mar 14, 2011
    Hi, just forget about what I wrote and asked, could somebody just tell me how to make a heating element that could reach temperatures of a 750W coil burner? I could use the power supply circuit if it would be needed, thanks.
     
  7. jan019

    jan019

    7
    0
    Mar 14, 2011
    Hello,

    so i found out that using the nichorme wire will be the best. WIll i be able to reach tempertatures of 500 - 800ºC with nichrome wire? If yes then how much volts would i have to supply and how long and thick would the nichrome wire have to be? Thanks

    John
     
  8. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,171
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    Jan 21, 2010
    Do you have some nichrome wire? Do you know what sort you can get?

    There are different types of nichrome wire, with different resistance characteristics. Also the wire thickness will make a huge difference.

    Many of these things are interrelated, so it is very hard to specify exactly what you need when you supply none of he information needed.

    If your source was (say) a heater element, and you wanted it to glow red hot from a low voltage source (as presumably it did from the mains) then you need the same current to be drawn. As such, you need a shorter length. The length required would be in proportion to the voltages. So if it was rated for 110V and you are powering it from 12 volts, you would require 12/110 of the original length (for this purpose AC and DC can be considered the same). If the original device was rated at 1100 watts (10A), then the new shorter length will draw 10A at 12V to glow the same red hot as the original full length did at 110V.

    If you have a power source that cannot manage 10A, then you need a finer nichrome wire. A finer wire will have a higher resistance and will draw less current at the same voltage. However the amount you require will also differ because the heat may be radiated at a proportionately different rate.

    If you don't know how long the wire should be, start with something too long and reduce the length until you get the right amount of heat (glowing red?). As you reduce the length, the current drawn will increase, and the power dissipated per unit length of the wire will increase faster (since current is increasing and length is decreasing).

    If the length you end up with is too short, or the current too high, then you need a still finer wire.
     
  9. jan019

    jan019

    7
    0
    Mar 14, 2011
    Hi,

    Thanks very much for the great and informative reply. I will check the store tomorrow what kind of nichrome wire they have and will return here with the info I got.

    So, if I understood correctly, then if I would get a really thin nichrome wire then it would need less amps to get to the same temperature as the thicker wire would get to with more amps? Or does only the length affect this?

    With the power source it will be harder, because i don't really want to use the power circuit or i will get fried(i am a real beginner)... The most mAh i have is 2000mAh and that's from a 1.2 volt battery. So my questions is from what can i get about 12volts and a good mAh at the same time? (Except the power circuit) Or if I would get a thin nichrome wire maybe i could use a 4.5v heavy duty battery what do you think?
     
  10. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,171
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    Jan 21, 2010
    yes, you probably want fine wire. If it's too fine you can use parallel strands.

    mAh is a measure of capacity not current.
     
  11. jan019

    jan019

    7
    0
    Mar 14, 2011
    Yes I know, but if my power source(for example a battery) has a low mAh then it will last only very shortly with a lot of ampers beign pulled out of it no?
     
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