Announcement

Collapse
No announcement yet.

The Resistor FAQ

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    The Resistor FAQ

    The Resistor F.A.Q

    Resistors are a very important part of a Circuit. We all know that every little bit counts! So.. here's as much as you should need to know about Resistors that I know. (Mind you, I'm still learning; and in fact this is helping me to learn. Hope other's find help here!)


    What's the Schematic Symbol for a Resistor?





    What's the Code for all The Colored Strips on a Resistor?






    Here's two Free Resistor Code Apps for help:

    Electronics Assistant V4.31 & Resistor Color Coder 2.1



    How can you tell, just by looking at a resistor what 'brand' it is? Or Can you?

    Knowing the 'BRAND' of the Resistor isn't necessary. I would like to hear experienced Techs own loyalties on this however! So, what's the best BRAND of resistors in your opinion? (If someone Can, please do tell!)

    How can you tell what 'KIND' of Resistor A resistor is? Is it a Carbon Composition, Carbon Film, Metal film, Metal oxide Or wire wound?

    Metal Film:


    http://www.resistorguide.com/metal-film-resistor/





    I found these worth their read: http://electronics.stackexchange.com...nd-what-values

    https://learn.sparkfun.com/tutorials/resistors/all

    How do I know what Wattage the resistor is that I'm replacing?

    The Schematics give Voltage (V) to the Resistor and you know the Resistor's Ohm Value (From color codes). So.. after you Find Current (I) (from I= V/R) then you find P (wattage) = V(squared)/R






    Here's a Quote from Mariushm (BadCaps Veteran):

    "Usually, [the] white/cream resistors are carbon film, blueish/green resistors used to be metallic , carbon film resistors usually have lousy temperature coefficient and larger tolerance (5-10%) High wattage resistors are wirewound usually (let's say 1w or higher).

    Power dissipated in a resistor is calculated by formula IxIxR where i = current and r=resistor value and generally the recommendations are to not exceed about 70-80% of the resistor's wattage rating. 1w resistors are quite large. When in doubt, you can go with 0.5w resistors or 1w resistors instead of 0.125w or 0.25w resistors.



    Here's some other Resources (on Wattage):
    http://techtalk.parts-express.com/sh...wattage-rating

    http://www.robogaia.com/how-to-calcu...r-wattage.html

    On Resistors:

    http://www.mikroe.com/old/books/keu/01.htm

    What is the Electronic Industries Association (EIA) 'Preferred Values' for Resistors?

    Easiest Answer is to give you this site link:

    http://www.logwell.com/tech/componen...or_values.html

    Any additional information that is relevant will be greatly appreciated. Please add to this Museum of Needed Electronics Information! Namaste- <><

    Attached Thumbnails
    Attached Files
    Last edited by Keshetisrael; 03-24-2014, 03:56 PM.

    #2
    The Resistor FAQ

    Personally, I'd really appreciate it if you wouldn't link to that ad filled site informer.com ... it basically spams Google with tons of keyword generated URLs ... just look at https://www.google.com/search?q=site%3Ainformer.com to see what I mean. Don't condone that style of website by linking to it.

    There are open source or free tools that are much more useful than a simple resistor color thing, for example I can mention Electronics Assistant : http://www.electronics2000.co.uk/


    As for the other questions.. usually white/cream resistors are carbon film, blueish/green resistors used to be metalic , carbon film resistors usually have lousy temperature coefficient and larger tolerance (5-10%)
    High wattage resistors are wirewound usually (let's say 1w or higher).

    Power dissipated in a resistor is calculated by formula IxIxR where i = current and r=resistor value and generally the recommendations are to not exceed about 70-80% of the resistor's wattage rating.

    1w resistors are quite large. When in doubt, you can go with 0.5w resistors or 1w resistors instead of 0.125w or 0.25w resistors.

    Comment


      #3
      Re: Resistors

      Here's a sampling of power resistors ranging from 3 watts to 225 watts. The one on the far left is a slider type variable resistor missing the slider.
      Attached Files

      Comment


        #4
        Re: Resistors

        "A typical radio shack resistor you will often see is a 2.2kohm resistor with 10% tolerance. The bands are "Red" (2), "Red" (2), "Red" (times 10^2), "Gold" +/- 10%." FYI: GOLD is 5%
        Never stop learning
        Basic LCD TV and Monitor troubleshooting guides.
        http://www.badcaps.net/forum/showthr...956#post305956

        Voltage Regulator (LDO) testing:
        http://www.badcaps.net/forum/showthr...999#post300999

        Inverter testing using old CFL:
        http://www.badcaps.net/forum/showthr...er+testing+cfl

        Tear down pictures : Hit the ">" Show Albums and stories" on the left side
        http://s807.photobucket.com/user/budm/library/

        TV Factory reset codes listing:
        http://www.badcaps.net/forum/showthread.php?t=24809

        Comment


          #5
          Re: The Resistor FAQ

          Can anyone tell me what watt this resistor is?

          Comment


            #6
            Re: The Resistor FAQ

            White , Yellow, Black as far as I can tell : 9 4 0 = 94 x 10^0 = 94 x 1 = 94 ohm.



            Attached Files
            Last edited by mariushm; 04-09-2014, 09:02 AM.

            Comment


              #7
              Re: The Resistor FAQ

              Originally posted by mariushm View Post
              White , Yellow, Black as far as I can tell : 9 4 0 = 94 x 10^0 = 94 x 1 = 94 ohm.



              thanks for the reply but its not the ohms im looking for its the watt.
              its brown black yellow gold.
              so my calculations are 100k with 5% tolerance.
              but its quite a big resistor so unsure of wattage! probs just going to get a 2W and hope for the best!

              Comment


                #8
                Re: The Resistor FAQ

                The pic is pretty blurred and can't tell what the coin is but that looks to me like a 1W 100K 5%
                brown black yellow gold

                Comment


                  #9
                  Re: The Resistor FAQ

                  hi its a uk penny. your colours are correct. ill get a 1 watt aswell as the 2 watt

                  Comment


                    #10
                    Re: The Resistor FAQ

                    It probably won't be a problem using a 2W if it fits.

                    Comment


                      #11
                      Re: The Resistor FAQ

                      cheers steve

                      Comment


                        #12
                        Re: The Resistor FAQ

                        High wattage resistors are wirewound usually (let's say 1w or higher).
                        2 W resistors are not all wirewound, there are many types of 2 W metal film resistors. 5 W and higher are always wirewound.

                        Comment


                          #13
                          Re: The Resistor FAQ

                          Ok struggling with this resistors value?
                          Anyone able to help?
                          the pink ones.

                          Comment


                            #14
                            Re: The Resistor FAQ

                            Looks like brown, black, gold, red, black.

                            Wasn't aware gold could be a middle band

                            Comment

                            Working...
                            X