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Thread: 4 ohm resistor?

  1. #1
    Join Date
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    Default 4 ohm resistor?

    i am having trouble finding any 4 ohm resistors locally and need one this weekend if at all possible.
    an they need to be 3/4 to 1 watt resistors

    so would 4 seperate 1 ohm 3/4 or 1 watt soldered together in a line work?

    or would i need 1/4 watt or what?

    this may be a stupid question but i dont want to take any chances.


    thanks
    -Josh

  2. #2
    Join Date
    Jul 2007
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    west sussex uk
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    Default resistors

    hi
    yes four 1ohm in series 3/4w should work just fine
    you can allway double check with a multimeter to make sure before you use it,
    as a rule series doubles parrallel halfs.
    regards
    chris

  3. #3
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    Default

    awesome thanks!
    -Josh

  4. #4
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    Default

    Regarding the wattage. If you needed 4ohms of resistance at 1W, then four 1 ohm 1/4 watt resistors will work. The wattage is just identifies how much power the resistor can dissipate. A 4 ohm 1/4W resistor is the same as a 4 ohm 10,000W resistor. The only difference is you can pump a whole lot more amperage thru a resistor with a higher wattage rating.

    Its actually kinda neat to watch a 1/4 or 1/2 watt resistor try to dissipate 10-20W of power!

  5. #5
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    Default

    Quote Originally Posted by DZ View Post
    Regarding the wattage. If you needed 4ohms of resistance at 1W, then four 1 ohm 1/4 watt resistors will work. The wattage is just identifies how much power the resistor can dissipate. A 4 ohm 1/4W resistor is the same as a 4 ohm 10,000W resistor. The only difference is you can pump a whole lot more amperage thru a resistor with a higher wattage rating.

    Its actually kinda neat to watch a 1/4 or 1/2 watt resistor try to dissipate 10-20W of power!

    awesome! well thats good to know!
    -Josh

  6. #6
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    Default

    You are better off using (5) 20 ohm resisters in parallel.

    That way you get the advantage of adding the power handling capabilities of each resister. So if each one is a 1/2 W all of them would be able to handle about 2.5W.

    Also, do not use the sand cast power resisters. They are coils of wire and therefore have a measurable inductive reactance that will mess with the top speed at which you can modulate the diode!

    BTW putting them in parallel will also reduce the inductive reactance of the whole thing.

    Use good metal film resisters.

    James.

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