How to Select the correct Component?

Discussion in 'Homework Help' started by cpleng7, Jan 6, 2011.

  1. cpleng7

    Thread Starter Active Member

    Dec 18, 2008
    Currently I have design my circuit and now I want to purchase the component, can someone teach me which one is correct?

    For example resistor have a lot of type , let take the example the fix value resistor, there are 1/4 W , 1/2W , 1W. How to select these component?
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    With no knowledge of the circuit, it's kind of hard to be definite about the resistor wattages. The power dissipated in a resistor is equal to the square of the current times the resistance, so you can use that formula to see if you need resistors larger than 1/4 watt.
  3. Audioguru

    New Member

    Dec 20, 2007
    Derate resistor power by half because a resistor operating at its rated power is hot enough to burn you or melt plastic insulation.
    A resistor operating at its power rating will overheat if it is enclosed because it needs free flowing ambient air at room temperature.
  4. Georacer


    Nov 25, 2009
    Of course, heat is a relative quantity. Even in a medium amplifier, the current amplifier resistors will be too hot for you to touch but hopefully not hot enough to burn your project.