Resistors ??

Discussion in 'General Electronics Chat' started by Dr.killjoy, Nov 22, 2013.

  1. Dr.killjoy

    Thread Starter Well-Known Member

    Apr 28, 2013
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    I picked up a batch of resistors off ebay and really like them but I wanted to know what Ohm ratting do you guys use and is it really necessary to 146 value resistor kit or just buy common size ( Whats are common?? ) ???




    Thanks
    Jason SR
     
  2. MrChips

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    Oct 2, 2009
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  3. wayneh

    Expert

    Sep 9, 2010
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    Some kits have varied numbers of the included values, e.g. many more 1,10, and 100K resistors than less common values. But I like having at least some of every value. Pain in the arse when you don't have the one you need.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
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    Makes no difference what selection you buy, the next project will always call for one you don't have!;)
    Max.
     
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  5. #12

    Expert

    Nov 30, 2010
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    My resistor cabinet is 24 values wide by 9 powers of ten tall, from .1 ohm to 56 megs, but if I had to go spare, I'd use the dial on my scope. 1,2,5 times powers of ten.
    .1, .22, .47 ohms to 10 meg, 22 meg and 47 meg. That's only 27 values. Useless for 1% analog circuits but enough to do a proof of concept for nearly anything.
     
  6. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Foro the e12 series, (E6 is every other one). I started with the E6 series and evolved o the 12 series. Like #12, I think less is more. e6 is plenty and #12 gets by with an E3.

    1.0
    1.2
    1.5
    1.8
    2.2
    2.7
    3.3
    3.9
    4.7
    5.6
    6.8
    8.2

    Repeat
    10
    12
    ...
     
  7. #12

    Expert

    Nov 30, 2010
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    I have E24 and more. A lot of 1% resistors are in those drawers, but the truth is, an E3 set will get you by for "proof of concept" work. Most of what I do now is on paper. When I have a doubt, I can go to the work bench, usually connect less than 10 parts, and verify any doubt I have in mind. After that, I can pencil whip the rest of the design. Other people use simulators. They are cheaper than keeping an inventory, but they have limitations. It depends on how well you understand a simulator whether you can trust the answers it gives. I don't understand simulators, but I understand this: Electrons can not lie. If a real, physical circuit made of discrete parts works, there is no room for argument.
     
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  8. MrChips

    Moderator

    Oct 2, 2009
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    I agree.

    10, 22, 47 over six decades works fine for most digital applications.

    The same idea goes for capacitors.
     
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  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    I couldn't agree more on the capacitor line. Unless someone is making colpits oscillators, no need for moe than e3
     
  10. WBahn

    Moderator

    Mar 31, 2012
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    I agree as well. E3 let's you get at least an approximation for almost anything for proof of concept. Plus, it's easy to parallel or series connect them to whip up something close to intermediate standard values.
     
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  11. #12

    Expert

    Nov 30, 2010
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    Much like going on vacation, beginners pack heavy. When you look at the landmark experiments done by the pioneers in electronics, the simplicity of the designs is usually the most striking part.

    I had to go through years of making and measuring precision designs before it soaked in that the math really works and precision is exactly what you make of it. Now I can look at a 50% error, know where it's coming from, and know whether a properly calculated component will correct that. When you get that much experience under your belt, E3 will get you where you want to go. For beginners trying to get real circuits to work, and to develop the mental leap of trust from theory to practice, I'd think E6 would be sufficient.
     
  12. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    The same mostly applies to multimeters as well. A meter that gives +/-10% accuracy is good enough for most proof of concept and most digital circuits. Beginners should pay for the fluke 87 when a $5 harbor freight meter can be free with coupon. Spend money on other things until (more / better) is needed.
     
  13. wayneh

    Expert

    Sep 9, 2010
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    Years ago I went to Radio Shack and bought something like this (1/4 watt) or this (1/8W). It's served me well.
     
  14. WBahn

    Moderator

    Mar 31, 2012
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    Same here. About 30 years ago and I still have most of them since I reuse components when I'm breadboarding.
     
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