After you've worked with electronics for a time, you'll begin to recognize the standard values of parts. There are 24 standard values per decade for resistors and when what you think are the first two digits look "funny", you'll quickly start from the other end to find a more familiar value. The 24 standard values for 5% resistors are 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82 and 91. That is, you'll find as a standard value 0.62, 6.2, 62, 620, 6.2K, 62K, 620K, 6.2M and 62M ohms, although the first and last won't be very common, especially the 62M. 10% standard values use every other of the 5% values, 20% standard values use every other of the 10% values, always beginning with 10.
The 24 standard values for 5% resistors are 10, 11, 12, 13, 15, 16, 18, 20, 22, 24, 27, 30, 33, 36, 39, 43, 47, 51, 56, 62, 68, 75, 82 and 91. That is, you'll find as a standard value 0.62, 6.2, 62, 620, 6.2K, 62K, 620K, 6.2M and 62M ohms, although the first and last won't be very common, especially the 62M.
Dean
Generally, the only ones that you'll use are 10, 12, 22, 27, 33, 47, 56, and 68.
With these, you can approximate values or use them in series and parallel.
theres 3 resistors im doing something wrong on or they are bad.all 3 are the same,br-bl-rd-gld...i have 10*100=1000 with a tolerance of 5%(50) these resistors are on 3 totally diff parts of the same board..2 of them are reading 799 wich im confused to wich way to lean..good or bad.. my reading should be from 950 to 1050..the third one really got me.its 01.2..
im using a fluke to test.
when a res goes bad is the reading tottaly off or can it be a lil bit off the tolarence and still not work..or is it open..
what causes a res to go bad
is there visual evidince when it goes bad
when i test the ends is it ok to test the sodered part if my probe cant fit between the bottom of the res and the board
theres 3 resistors im doing something wrong on or they are bad.all 3 are the same,br-bl-rd-gld...i have 10*100=1000 with a tolerance of 5%(50) these resistors are on 3 totally diff parts of the same board..2 of them are reading 799 wich im confused to wich way to lean..good or bad.. my reading should be from 950 to 1050..the third one really got me.its 01.2..
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when i test the ends is it ok to test the sodered part if my probe cant fit between the bottom of the res and the board
Generally, the only ones that you'll use are 10, 12, 22, 27, 33, 47, 56, and 68.
With these, you can approximate values or use them in series and parallel.
I think that a more accurate thing to say would be that you'll use those the most, although I don't know why you included the 12 with that group since it's only 20% away from 10. However, I certainly don't agree with the approximating values or using them in series and parallel. Nothing like having to have triple the number of resistors necessary for each project you build if you limit yourself to a very narrow range of value like that.
You're much better off stocking a few of all the 5% standard values rather than kludging together values from what you can find laying around. Series and parallel combos can push power and voltage ratings if you're not careful.
I certainly don't agree with the approximating values or using them in series and parallel.
You're much better off stocking a few of all the 5% standard values rather than kludging together values from what you can find laying around. Series and parallel combos can push power and voltage ratings if you're not careful.
It all depends on the kinds of projects you do. The stuff that I make can manage having resistor values a little off.
Dean Huster said:
Nothing like having to have triple the number of resistors necessary for each project you build if you limit yourself to a very narrow range of value like that.
I try to avoid doing that, and if I do, I limit myself to no more than 2 resistors per series/parallel combination. If I can't manage to do that, it means giving up the project or making a trip to the nearest good electronics store; conveniently located 2 cities away.
If I can't manage to do that, it means giving up the project or making a trip to the nearest good electronics store; conveniently located 2 cities away.
Sounds like you need to be stocking up on resistors by doing some board salvage or begin collecting parts via mail order.
I can't sympathize with you on your need to travel to find parts. The nearest electronics store that's worth the trip for me is 3 hours away. There's a Radio Shack in the nearest town 12 miles away, but Radio Shack in the U.S. is as worthless as the mammary glands on a boar as they carry very few piece parts these days. They're only good for cell phones, overpriced computers and other consumer products.
A node is a node; the wire between components is CONSIDERED to have no resistance, and anything connected with wire is on the same node, so you should be ok here.
If the thing was designed well, resistors normally do not fail, and when they do they tend to fail open, or partially open. The cause of the failure may be elsewhere in the circuit, which has cause increased current through, or voltage across a resistor, finally causing the demise of the resistor.
Generally the most popular values are multiples of 10, followed closely by 47 and 22. This is because 10, 22 and 47 form the E3 series which is still very common even though 50% tollerence resitors probably went out of fashion back in the 1890s.
Generally when stocking an inventory I resomend a set of the E24 values, plus more of the E12 values, even more of the E6 values and loads of the E3 values. Generally as the E number goes up, the values become less common and as the E number goes down they become more common.