Resistor and capacitor common values?

Discussion in 'General Electronics Chat' started by SlowCoder, Mar 28, 2012.

  1. SlowCoder

    Thread Starter New Member

    Mar 25, 2012
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    I viewed this sheet of resistor and capacitor standard values.

    Some people say some of the values are not common to get any more, which means that if I don't have a particular value handy, I'd have to connect other values in series (such as 100ohm and 2 10ohm to get 120ohm). But then when I talk about series connections, people tell me it's not common to connect multiple resistors in series. So, what's the truth here? Is it easy to get all of the values, or are my options limited, and I would need to connect in series to get proper resistance?
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    Most people don't use 5% and 10% resistors any more because, in surface mount components, there is no cost advantage over 1%. Check out a table of 1% values for much greater granularity.
     
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  3. MrChips

    Moderator

    Oct 2, 2009
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    In most cases you do not need exact values. Sometimes if you are within 20% that is good enough. For example, 100-ohm may be just as good as 120-ohm.

    It all depends on the specific application. In some digital circuits, twice the value may not make any difference.

    Learn to identify when precision matters.
     
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  4. Wendy

    Moderator

    Mar 24, 2008
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    I use 5% ¼W resistors for my master kit, and buy what ever else I need.

    For most beginners surface mount is not really practical. I have a standing offer to help folks that need resistors. The reason is my costs are pretty low, 2¢ each. It costs more to put a stamp on it.

    Bought a protoboard yet?

    [​IMG]
     
  5. KJ6EAD

    Senior Member

    Apr 30, 2011
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  6. Papabravo

    Expert

    Feb 24, 2006
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    The price of SMT components drives everything else because the volumes are huge. Check the relative prices of leaded 1% resistors versus 5% resistors. Digi-key has a bag of 200 leaded 1% resistors for about $3.50
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    I paid 40¢ for a 20 pack of each value. It still ran over $40 or so for the entire kit, but now I never have to worry whether I have a resistor on hand. Liberating, that.

    If I were to do the same with SMT at $3.50 it would be over $300. Fortunately Tanners has some SMT. One of these days I will play with it, I've already bought a 100 pack of 2N2222s for just a couple of dollars.

    The other side is I can use 1/8W resistors in lieu of SMT.
     
  8. bertus

    Administrator

    Apr 5, 2008
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  9. #12

    Expert

    Nov 30, 2010
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    I've never met a standard resistor value that I couldn't buy in the low wattages like 1/8th or 1/4 watt. That's why putting resistors in series is not a common practice.

    It gets more necessary in high watt circuits because no hobbyist stocks a full set of 10 or 20 watt resistors.
     
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