Resistor to make heater

Discussion in 'The Projects Forum' started by rafaelluizmesquita, Aug 13, 2013.

  1. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
    38
    0
    Hey guys,

    I am trying to make a resistor made heater in low cost. Do any of you have any experience? It goes to the 110V in the outlet with a AC 4" fan. I am not sure which resistor to buy...

    The plan is to use 4 or 8 resistors to reach about 100W without use the full power of the resistor. So I thought in use some 25W resistors or so... What do you guys say about it?
     
  2. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Is this supposed to be heating a room or something else? For a room 100W is definitely not enough, and for anything else it probably is way too much.
     
  3. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
    38
    0
    No... it is just a small cubic box of about 20" as a side...
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,571
    2,381
    The effectiveness of any heater to maintain a constant or minimum temp depends on the range of the ambient temperature.
    The temperature range here is -40°C to +40°C !!
    Max.
     
  5. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    Just get a 100W lightbulb and use a thermostat. There are many "incubator" projects out there.
     
  6. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
    38
    0
    Hey max... well... I expect that the box stay somewhere around 30C... I believe that the room temperature will be around 10C during the winter, because we will have an AC working as a heater to the room. The room is maybe 2.00m x 1.80m x 1.80m.

    The room and the box will stay constantly closed, the only in to the room is the AC/heater and the only in and out to the box is two fans that makes the air circulate in the box...
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    100W is probably too much for a box that small, but anyway if you use a thermostat you can experiment with different wattage bulbs.
     
  8. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
    38
    0
    the problem with using a light bulb is that this is an light observatory. Everything needs to be nice and dark inside. So I cannot use a wooden box with a couple of lamps in it because it is just gonna blow up because of the high heat inside the box. So it needs to be some sort of resistor.

    I am thinking in use 4 of those guys here: http://www.caddock.com/Online_catalog/Mrktg_Lit/MP9000_Series.pdf

    The one with 30W 500ohms... and use a peace of metal to dissipate some heat.
     
  9. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    Watts are watts. The box doesn't care where they come from.

    If visible light is an issue, you can buy IR heating lamps. They're more expensive than regular bulbs but throw off far less visible light.

    The great thing about a lightbulb is the negative temperature response, meaning they increase resistance when they get hot, so there is never a chance of thermal runaway. They are self-controlling and purpose-built to dissipate the heat they produce.
     
  10. rafaelluizmesquita

    Thread Starter Member

    Aug 8, 2013
    38
    0
    My only concern is that we already reproduce that in the lab and besides the fact that we cannot have any lights of any nature, IR or UV or visible... the light bulb will only get hotter and hotter increasing the resistance. Eventually it will just explode. I cannot afford mixing fire with the thing I do... So no chance to the light bulb I'm sorry...
     
  11. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
  12. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    You're seriously confused. [post #10] The lightbulb is far safer against the problem you describe than ... just about any other solution. That is why they are universally used for such things. If the box gets too hot, you need to use a smaller bulb and/or control it with a thermostat.

    But you cannot tolerate light, fair enough. I'd stick the lightbulb inside a ribbed aluminum box, to shield the light and still allow heat to dissipate.

    If you are dead set against a light bulb, you'll need to describe the power supply you have available, so that a heater can be chosen to run on that power.

    Note that mains-direct projects are not allowed for discussion in this forum.
     
  13. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    So a light bulb plugged into a wall socket is against the rules of this forum. :p
    (of course you really didn't say it was a mains powered light bulb..but that could be assumed easily)

    rafaelluizmesquita
    To obey by the rules of this forum you would need to use a transformer or other type of isolated ac/dc converter for any project on here..

    There is nothing wrong with using a resistor.. Not sure why wayne so against the idea but whatever.
    Its totally fine and done all the time. However the fact you said you want to plug it into the 110v wall outlet is against the rules of this forum for safety reasons.

    Make sure the wattage rating of the resistor is at least twice (if not more) what you intend to dissipate and go for it (safely)
     
  14. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    Is it? I honestly don't know. Bicycle lighting falls under automotive modification, so I can't pretend to understand the rules, but I believe it might be. I thought about pointing it out but I knew that would expose my ignorance of the rules. :p
    I have no problem and have done it myself (although using a computer PSU as the power source, and a MUCH lower wattage). I was only reacting to the overly hasty dismissal of the light bulb idea that so many other folks find perfectly good, and ...
    ...I'd much rather talk about a light bulb than advising the OP how to plug resistors into the wall. Without great care, things could go very badly. :eek:
     
  15. mcgyvr

    AAC Fanatic!

    Oct 15, 2009
    4,771
    971
    light bulbs are boring though :D
    smoking resistors and tripping breakers is fun :p


    The information contained in this post is provided by an individual who is fully aware of the safety dangers associated with mains powered voltages and the practices necessary to ensure safety. Please do not try this at home. ;)
     
  16. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    Haha, I guess I should have suggested a flashing LED. That always seems to get attention around here. ;)
     
  17. tubeguy

    Well-Known Member

    Nov 3, 2012
    1,157
    197
    How about making the box's bottom a square of metal with a light bulb
    below? No light inside, heat rises. Thermostat inside to regulate the bulb.

    Oh, and add a flashing LED to show it's working.

    Wait a minute ... a digital temperature display :cool:
     
    Last edited: Aug 13, 2013
  18. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    And of course a text sent to your smartphone. Solar powered, of course.
     
  19. biscuitownz

    New Member

    Aug 9, 2013
    25
    0
    Why not use a peltier?
     
  20. wayneh

    Expert

    Sep 9, 2010
    12,156
    3,063
    So far we only have a wall outlet as a power source.
     
Loading...