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driving an output with a thyristor

Discussion in 'General Electronics Discussion' started by burassu, Dec 4, 2011.

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  1. burassu

    burassu

    36
    0
    Jul 1, 2011
    I bought a 25 W under tank heater which I am going to drive it with an optoisolator and a thyristor. Do iI have to connect a resistor rated more than 25W?
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,491
    2,833
    Jan 21, 2010
    You need to use a resistor with a power rating at least a little larger than the power it is called on to dissipate.

    I assume the direct answer is "no", but you'd have to provide us with a circuit diagram to see where the resistor is used, what its value is, etc...
     
  3. burassu

    burassu

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    Jul 1, 2011
  4. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    I see what is presumably a MOC3010, one 180 ohm and one 2.4k resistor. A proper datasheet can be found here. Those resistors can be standard 0.25W size.
     
  5. burassu

    burassu

    36
    0
    Jul 1, 2011
    I don't know because once I built that circuit and as a load I connected a bulb, the resistor started to burn , I increased it to 1w and it did the same , then I replaced it with a 2 w and it worked perfectly. That why I have a doubt on which type of power rated reistor I am going to use.
     
  6. Resqueline

    Resqueline

    2,848
    2
    Jul 31, 2009
    I don't know which of the resistors you replaced with 270 ohm, or how it would affect the circuit. The datasheet does not specify high wattage.
    Neither do we know what kind of a triac you're using. If it is connected incorrectly or has a hard time trigging then the resistors may well burn.
     
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