Home |
Search |
Today's Posts |
#1
|
|||
|
|||
Where to get 1watt 1% resistors.
Where to get 1watt 1% metal film resistors?
Nobody seems to stock them. Newark, Mouser ect want 500pc min order for the Vishay/Dale. Any ideas?? |
#2
|
|||
|
|||
Where to get 1watt 1% metal film resistors? ** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series. ............. Phil |
#3
|
|||
|
|||
I just bought a single Dale RN65 from Mouser less than a month ago...
According to Vishay/Dale, the RN65 is rated at 1/2W. However, this is the milspec rating; the commercial rating is actually 1W. Similarly, the RN60 is actually what we consider a 1/2W resistor but for the milspec rating it is a 1/4W resistor. According to their own spec sheets, the RN series are the same resistors as the CMF series - just with different markings and ratings. See: http://www.vishay.com/docs/31018/cmfind.pdf http://www.vishay.com/docs/31027/cmfmil.pdf j wrote: Where to get 1watt 1% metal film resistors? Nobody seems to stock them. Newark, Mouser ect want 500pc min order for the Vishay/Dale. Any ideas?? |
#4
|
|||
|
|||
wrote in message ... Where to get 1watt 1% metal film resistors? Nobody seems to stock them. Newark, Mouser ect want 500pc min order for the Vishay/Dale. Any ideas?? Antique Electronic Supply http://www.tubesandmore.com/ Iain |
#5
|
|||
|
|||
Phil Allison wrote:
Where to get 1watt 1% metal film resistors? ** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series. ............ Phil That'd be like a 1W 2% resistor |
#6
|
|||
|
|||
"Dope mcSmoke" Phil Allison wrote: ** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series. That'd be like a 1W 2% resistor ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. ......... Phil |
#7
|
|||
|
|||
"Phil Allison" wrote
That'd be like a 1W 2% resistor ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. Phil, those two statements appear contradictory, because your use of "%" changes from the first to the second. Or you are wrong... What improves is the *chance* that a resulting value will be within tolerance. Since quoted tolerance assumes a particular distribution of values around the quoted value, improving that chance is the same thing as narrowing the tolerance. cheers, Ian |
#8
|
|||
|
|||
"Ian Iveson" ** A colossal, context REMOVING, ****ing pommy IDIOT !!!! ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. Phil, those two statements appear contradictory, because your use of "%" changes from the first to the second. ** Only seems that way to someone with autism. Or you are wrong... ** Go get rooted - you autistic prick. What improves is the *chance* that a resulting value will be within tolerance. ** WRONG. It will be within tolerance for all non faulty resistors. Since quoted tolerance assumes a particular distribution of values around the quoted value, ** No it does not. The % tolerance of a resistor is the MAX amount that any sample will differ from the nominal value INCLUDING the effects of a normal service life. ......... Phil |
#9
|
|||
|
|||
Phil wrote [below...seems a bit angry again...]
Perhaps a simple illustration will help you, Phil. Take an example 100R 1% resistor. Let's say the probability of it being only 99R is P. Take another from the same batch. The probability of it also being 99R is also P The chance of them *both* being 99R is Psquared. Since P is always less than one, Psquared is always smaller than P. There is no other combination of values that adds up to 198R, so the chance of the two in series being 1% is smaller than either on its own. OTOH, there are many possible combinations of values, the one larger and the other smaller than the nominal value, or vice versa, that could add up to the nominal value, making it more likely that two in series would be near the nominal value. In other words, even if the probability distribution of values in the batch is flat with vertical limits at 1%, as you suggest, the distribution of two in series will be an inverted U shape. With many resistors in series, it will approach a normal distribution I think. I have been trying to find out whether resistors are sampled, or if each one is measured. The above works for either but, if they are sampled then the compound resistor will have a better tolerance than the single value. So, does "1%" mean every one, or is there a confidence limit, perhaps 99.9%within 1%? Anyone know whether the nominal value is the mean, mode, median, or none of those? Anyone know what the distribution is around the nominal value? I'm sure it's not actually flat. They aren't made by chance. cheers, Ian "Phil Allison" wrote in message ... "Ian Iveson" ** A colossal, context REMOVING, ****ing pommy IDIOT !!!! ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. Phil, those two statements appear contradictory, because your use of "%" changes from the first to the second. ** Only seems that way to someone with autism. Or you are wrong... ** Go get rooted - you autistic prick. What improves is the *chance* that a resulting value will be within tolerance. ** WRONG. It will be within tolerance for all non faulty resistors. Since quoted tolerance assumes a particular distribution of values around the quoted value, ** No it does not. The % tolerance of a resistor is the MAX amount that any sample will differ from the nominal value INCLUDING the effects of a normal service life. ........ Phil |
#10
|
|||
|
|||
"Ian Iveson" ** A colossal, context REMOVING, ****ing pommy IDIOT !!!! ** Only seems that way to someone with autism. ** Go get rooted - you autistic prick. ** WRONG. It will be within tolerance for all non faulty resistors. ** No it does not. The % tolerance of a resistor is the MAX amount that any sample will differ from the nominal value INCLUDING the effects of a normal service life. ......... Phil |
#11
|
|||
|
|||
Oops! Over the edge he goes...
"Phil Allison" wrote in message ... "Ian Iveson" ** A colossal, context REMOVING, ****ing pommy IDIOT !!!! ** Only seems that way to someone with autism. ** Go get rooted - you autistic prick. ** WRONG. It will be within tolerance for all non faulty resistors. ** No it does not. The % tolerance of a resistor is the MAX amount that any sample will differ from the nominal value INCLUDING the effects of a normal service life. ........ Phil |
#12
|
|||
|
|||
"Ian Iveson" ** A colossal, MASTURBATING, TOP POSTING , context REMOVING, ****ing pommy IDIOT !!!! ** Only seems that way to someone with GROSS autism. ** Go get rooted - you grossly autistic prick. ** WRONG. It will be within tolerance for all non faulty resistors. ** No it does not. The % tolerance of a resistor is the MAX amount that any sample will differ from the nominal value INCLUDING the effects of a normal service life. ......... Phil |
#13
|
|||
|
|||
"flipper" The "chance" of the pair being within tolerance is 100%. Well, if the individuals are within tolerance, as specified, that is. ** Correct. The tolerance number assumes nothing; they'll simply be within 1% ... ** WRONG. New Metal Film resistors are and need to be well within the 1% error maximum to allow for aging. You can still end up with 1% off and that's all a 1% tolerance says: ** Nope - the chances of being even 0.5 % are low with new stock. For example, take a resistor line that includes .1%, .5%, and 1% tolerance ranges. It is not uncommon for those to be selected from the same manufacturing process so the .1% resistors are culled out first, then the .5%, and then the remaining are 1%. ** Completely false. Metal film resistors of 0.1 % tolerance are made in a different way to guarantee stability over life of 0.05%. Lastly, to cover the subsequent message, tolerance is the initial tolerance, at 25C, as delivered to your doorstep and before you begin torturing the thing. Everything else, solder, lead stress, temperature coefficient, long term drift, surge, voltage stress, temperature cycling, etc. are in addition to the initial tolerance. ** That is NOT my experience over 40 years of dealing with the critters. The topic is tubular METAL FILM resistors that have been spiralled to a value. Forget any WW or composition types. .......... Phil |
#14
|
|||
|
|||
"flipper" wrote [below and...]
See the next post I made to Phil. You have made false assumptions about what I assumed. Whatever the distribution of single values, multiplying the number of resistors will make it more bell-shaped than it was. If 1% tolerance means that all the resistors are individually measured to be within 1%, then my statement that a compound resistor has a better chance of being within tolerance would be incorrect. But my main point, that compound resistors will be more tightly clustered around a nominal value and sparse at the edges, is true. Furthermore, I have said that resistors aren't manufactured by chance. That is, they don't make random values and then sort them. They actually target a particular nominal value for each batch. We should expect some kind of bell-like distribution, therefore. Looking at a few pages on the net, for example: http://www.circuitree.com/CDA/Articl...108386,00.html http://www.mcm.dupont.com/MCM/en_US/...pass_tech5.pdf you can see that this is true. The question to which I can't find an answer is, do they chop off the tails of the distribution? The only way that could be done would be by measuring every resistor. Looks like they do. If Phil is right when he says that normal service life is included, then they absolutely definitely *cannot* chop off the tails of the distribution. In any case, my main point about *chance* is correct: a compound resistor will probably be closer to its nominal value than the individual resistors it is made of. More points below in context: "Phil Allison" wrote That'd be like a 1W 2% resistor ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. Phil, those two statements appear contradictory, because your use of "%" changes from the first to the second. Or you are wrong... The part that's incorrect is thinking it improves the % accuracy, as the first, and correct, statement shows. If they're 1% tolerance they can be 1% off. That's what it means. And 2 of them together can be 1% off as well. The tolerance is 1%. What improves is the *chance* that a resulting value will be within tolerance. The "chance" of the pair being within tolerance is 100%. Well, if the individuals are within tolerance, as specified, that is. Ok, if they chop off the tails, which it seems they do (but still not certain...) Since quoted tolerance assumes a particular distribution of values around the quoted value, improving that chance is the same thing as narrowing the tolerance. Neither of those is correct. The tolerance number assumes nothing; they'll simply be within 1% and if they're all 1% off it's just as valid as if only one of them is off 1% off.. It is you who are apparently assuming a particular distribution. No, I am only assuming that it has a distribution, which it must have. Second clause of my statement is wrong only if they chop off the tails... Second, 'chance' has nothing to do with the tolerance unless you are 'hoping' to get something other than what's specified. But, in any case, the tolerance is neither 'improved' nor lessened. You can still end up with 1% off and that's all a 1% tolerance says: you can't *depend* on them being any closer than 1% and it doesn't tell you 'how much' you can or can't depend on it. And it 'might be' anywhere in-between. The *only* thing known is they'll be within 1% No, not the only thing. You know they are more likely to be closer, and you can calculate exactly by how much. You are getting carried away with your point now. You were better off keeping it simple. Which gets back to the distribution and the dangers of assuming one. There is bound to be a distribution. How could there not be? What you are probably thinking of is the classic bell curve distribution and assuming that distribution applies but it may very well not depending on how they're made and selected. I did not say that was my assumption, and my point does not require it. Actually it *is* bell shaped to begin with. The only question was whether they chop off the tails... For example, take a resistor line that includes .1%, .5%, and 1% tolerance ranges. It is not uncommon for those to be selected from the same manufacturing process so the .1% resistors are culled out first, then the .5%, and then the remaining are 1%. Which means the .1% resistors may very well have a classic bell curve distribution but the .5% values will have a .1% 'hole' around the .1% value and the 1% resistors will have a .5% 'hole' (might be multiple holes too). So your 'chances' of finding a right spot on 1% resistor might be virtually 0, unless there's not enough demand for .1% and .5% values so that some of the 'better' ones get the lower tolerance rating anyway to fill the larger demand in that market. Which means you can't even 'depend' on the dern 'hole' being there. This is more useful stuff, if it is true. But here you suggest that the 1% resistors do *not* have the distribution tails chopped by the selection process, so you have rather shot yourself in the foot. Once again, compound resistors, *regardless of the distribution of their components* will concentrate values around the nominal, and fewer will be found at the extremes. Also, "holes" near nominal will be filled in more than those at the extremes. Assuming distributions when none is specified can lead to disappointing surprises. You've said that so many times it's stopped making sense. Now, if you were hand selecting a tighter tolerance from a lower tolerance batch then pairing them might improve your yield because there might be more 'good' combinations of offsetting pairs than solely single values, if the unknown distribution allowed it. But, then, you can't necessarily count on that. (the manufacturer can because he knows the distribution) Yes you can count on it. Show me *any* plausible distribution where it would not be true. Now you are just making things up. Lastly, to cover the subsequent message, tolerance is the initial tolerance, at 25C, as delivered to your doorstep and before you begin torturing the thing. Everything else, solder, lead stress, temperature coefficient, long term drift, surge, voltage stress, temperature cycling, etc. are in addition to the initial tolerance. What subsequent message? Anyway, if you are correct here (evidence?), then it does at least mean that it is *possible* they chop the tails. Altogether you have been quite convincing on that issue...but where is your evidence? cheers, Ian PS More evidence for your chopping... http://www.keithley.com/data?asset=3871 |
#15
|
|||
|
|||
"flipper" The tolerance number assumes nothing; they'll simply be within 1% ... ** WRONG. You need to learn a new word. ** You need to go get ****ed - psycho. New Metal Film resistors are and need to be well within the 1% error maximum to allow for aging. Sorry, but no. ** Prove it. With real data. ** That is NOT my experience over 40 years of dealing with the critters. I don't know what you think your experience has been but the specification for tolerance is initial at 25C and the rest are add-ons. Always have been. ** Crap. For example http://www.universalimport.se/Mfr.pdf ** Meaningless. ........... Phil |
#16
|
|||
|
|||
"Ian Iveson" The question to which I can't find an answer is, do they chop off the tails of the distribution? The only way that could be done would be by measuring every resistor. Looks like they do. ** Metal film and other spiralled resistors are made initially as fully coated tubes of ceramic - then the film is cut into a spiral in an automatic lathe to from the final value. The same coated blank tube can make a range of values. The lathe machine that does the spiral cutting MEASURES the value as it cuts and STOPS when the pre-set value is reached. The accuracy and consistency depends on the speed at which the machine is producing finished resistors. Accuracy and consistency of within 1% is easy to achieve and so has became the industry standard - and every resistor is measured. .......... Phil |
#17
|
|||
|
|||
"flipper" "Phil Allison" ** Prove it. With real data. I did, below. ** That drivel was not any sort of data. You lose. .......... Phil |
#18
|
|||
|
|||
"flipper" ** ****ing imbecile. Has no idea how to distinguish fact from hunch. ........... Phil |
#19
|
|||
|
|||
Ian Iveson wrote:
Oops! Over the edge he goes... Man! what a ****storm. I'm glad I don't post an answer to all stupid comments the morons here make, at least they're less than in alt.guitar.amps |
#20
|
|||
|
|||
Phil Allison wrote:
"Dope mcSmoke" Phil Allison wrote: ** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series. That'd be like a 1W 2% resistor ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. ........ Phil Thinking about it now I realize that: two 1% 100R in series being 1% off could make 2*99R=198R or 2*101R=202R which is still 1% off, so you're right. But you still don't have to be a total bitch about it. |
#21
|
|||
|
|||
Wacky Willie in Portland has them by the boatload in odd sizes, but they
just moved and won't have their inventory back up until spring (my guess). I think they are going to put up an ebay store to sell their stuff--which is a hobbyists delight. I buy all my switches, connectors, caps, transfromers, resistors, hardward, etc. there. Costs about 5% of retail, but you have to be willing to sort through bins. wrote in message ... Where to get 1watt 1% metal film resistors? Nobody seems to stock them. Newark, Mouser ect want 500pc min order for the Vishay/Dale. Any ideas?? |
#22
|
|||
|
|||
DigiKey sells 1W and 2W metal films in small qty. too.
|
#23
|
|||
|
|||
"flipper" wrote in message ... On Fri, 07 Oct 2005 06:16:04 GMT, "Ian Iveson" wrote: "flipper" wrote [below and...] See the next post I made to Phil. You have made false assumptions about what I assumed. In the first place I didn't "assume," I made a guess of "probably" but, regardless, you claim I made a false assumption and then proceed to explain your assumption is precisely what I guessed it was. Nope. As I have said a number of times, I have corrected my original assumption, and I did so before you posted. My only error was to assume that the tails of the distribution are not removed by measurement and selection. I have discussed this several times. Whatever the distribution of single values, multiplying the number of resistors will make it more bell-shaped than it was. You don't end up with a bell shape, much less "more bell-shaped" by multiplying just any two arbitrary distributions together. The distribution of values of compound resistors is more bell shaped. That is, the more resistors in the string, the more the distribution tends towards a bell shape. I explained why before you posted, in my second post to Phil. If 1% tolerance means that all the resistors are individually measured to be within 1%, then my statement that a compound resistor has a better chance of being within tolerance would be incorrect. The tolerance specification is not a 'chance' you'll get a 1% resistor, you GET a 1 % resistor so it can't be a "better chance" with 2 when the 'chance' is 100% no matter what. How many more times? Read more carefully please. This point was conceded before your first post. Just to make it absolutely clear: this point was conceded before your first post. For example, immediately above. But my main point, that compound resistors will be more tightly clustered around a nominal value and sparse at the edges, is true. Depends on the distribution of the singles. *No it doesn't*. This is the bit you are making up. You have no idea really. Like I said, show me a plausible distribution where it would not be the case. Furthermore, I have said that resistors aren't manufactured by chance. That is, they don't make random values and then sort them. No one suggested they did. It would be the only way to get a flat distribution with vertical limits. My point is that the distribution cannot be flat to begin with. They actually target a particular nominal value for each batch. We should expect some kind of bell-like distribution, therefore. Looking at a few pages on the net, for example: http://www.circuitree.com/CDA/Articl...108386,00.html http://www.mcm.dupont.com/MCM/en_US/...pass_tech5.pdf you can see that this is true. For every resistor made by every manufacturer? It is bound to be some kind of bell shape, or inverted v or u. Doesn't matter because the issue is what the tolerance specification means, not what you're going to 'guess' from how you think they're made, sorted, culled, or not, or whatever. You don't get to decide what the issue is. You are continuing to harp about a minor point that I conceded before you posted. And you are wrong anyway. If they are not "culled", then the tails of the distribution will still be present, and you lose even the minor point you are clinging to. So "culling" *does* "matter". It is crucial to your trivial point. The question to which I can't find an answer is, do they chop off the tails of the distribution? The only way that could be done would be by measuring every resistor. Looks like they do. If Phil is right when he says that normal service life is included, then they absolutely definitely *cannot* chop off the tails of the distribution. He's not. Probably. In any case, my main point about *chance* is correct: a compound resistor will probably be closer to its nominal value than the individual resistors it is made of. Your statement was "What improves is the *chance* that a resulting value will be within tolerance" and the 'chance' is not better since the chance is 100% regardless. Otherwise they aren't 1% resistors. Sigh...harping again. More points below in context: "Phil Allison" wrote That'd be like a 1W 2% resistor ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. Phil, those two statements appear contradictory, because your use of "%" changes from the first to the second. Or you are wrong... The part that's incorrect is thinking it improves the % accuracy, as the first, and correct, statement shows. If they're 1% tolerance they can be 1% off. That's what it means. And 2 of them together can be 1% off as well. The tolerance is 1%. What improves is the *chance* that a resulting value will be within tolerance. The "chance" of the pair being within tolerance is 100%. Well, if the individuals are within tolerance, as specified, that is. Ok, if they chop off the tails, which it seems they do (but still not certain...) Doesn't matter HOW they're made. The spec is 1%. They'll be within 1%, or else they aren't 1% resistors. By "chop off the tails", I mean remove the tails of the distribution. That should have been clear from the context. The tails of a bell-shaped distribution are the two sides of the flare at the bottom of the bell. The difference, if you will, between a bell and an inverted U or V. Since quoted tolerance assumes a particular distribution of values around the quoted value, improving that chance is the same thing as narrowing the tolerance. Neither of those is correct. The tolerance number assumes nothing; they'll simply be within 1% and if they're all 1% off it's just as valid as if only one of them is off 1% off.. It is you who are apparently assuming a particular distribution. No, I am only assuming that it has a distribution, which it must have. Second clause of my statement is wrong only if they chop off the tails... Just being a 'distribution' doesn't mean monotonic, contiguous, 'bell shaped' or anything else. It just means there's more than one. But you ARE assuming all sorts of distribution characteristics. No I am not. Can you see now that you *are* assuming that I am making assumptions? You denied it, but it is true. No, I don't need to, for the purpose of my argument. Nonetheless, the assumption would be true if I made it. Second, 'chance' has nothing to do with the tolerance unless you are 'hoping' to get something other than what's specified. But, in any case, the tolerance is neither 'improved' nor lessened. You can still end up with 1% off and that's all a 1% tolerance says: you can't *depend* on them being any closer than 1% and it doesn't tell you 'how much' you can or can't depend on it. And it 'might be' anywhere in-between. The *only* thing known is they'll be within 1% No, not the only thing. Yes. From "tolerance: 1%" that is all you know: tolerance:1% You know they are more likely to be closer, Only if you ASSUME a particular distribution characteristic. In this case you ASSUME the distribution has more in the center than on the edges. Absolutely not. Now you are SHOUTING about my assumptions, even though you have denied accusing me of making them. Just where are you coming from, mr flipper? and you can calculate exactly by how much. Calculate from WHAT? Tolerance is 1%. Tell me what, from 1%, you use to 'calculate' the center clustering. The number of resistors in the chain, and the probability distribution of the values of the individual resistors. Of course that original distribution must be known, but it doesn't matter what it is. You are getting carried away with your point now. You were better off keeping it simple. Apparently not because you still seem to think you can divine a distribution from "tolerance: 1%." Seems to you, you say. Another fanciful aunt sally. Which gets back to the distribution and the dangers of assuming one. There is bound to be a distribution. How could there not be? Of course there is one. At last. Now survey all you have written here and ask yourself whether you are being honest. The problem is you assuming you know what it is from the completely dissociated number "tolerance:1%." Sigh... What you are probably thinking of is the classic bell curve distribution and assuming that distribution applies but it may very well not depending on how they're made and selected. I did not say that was my assumption, That's why I had to guess and said 'probably'. and my point does not require it. Actually it *is* bell shaped to begin with. The only question was whether they chop off the tails... It's not a relevant question to the matter of what tolerance means. There you are trying to shift the topic again. For example, take a resistor line that includes .1%, .5%, and 1% tolerance ranges. It is not uncommon for those to be selected from the same manufacturing process so the .1% resistors are culled out first, then the .5%, and then the remaining are 1%. Which means the .1% resistors may very well have a classic bell curve distribution but the .5% values will have a .1% 'hole' around the .1% value and the 1% resistors will have a .5% 'hole' (might be multiple holes too). So your 'chances' of finding a right spot on 1% resistor might be virtually 0, unless there's not enough demand for .1% and .5% values so that some of the 'better' ones get the lower tolerance rating anyway to fill the larger demand in that market. Which means you can't even 'depend' on the dern 'hole' being there. This is more useful stuff, if it is true. But here you suggest that the 1% resistors do *not* have the distribution tails chopped by the selection process, so you have rather shot yourself in the foot. I didn't 'shoot myself in the foot' because I'm not trying to 'prove' whatever the heck you seem to think. The only point was you can't know what the distribution is, certainly not from "tolerance:1%," and it can be dangerous to assume one, as the example shows. Read again more carefully. If the tails aren't chopped, *everything* you have said is nonsense. You are harping again. Once again, compound resistors, *regardless of the distribution of their components* will concentrate values around the nominal, and fewer will be found at the extremes. Also, "holes" near nominal will be filled in more than those at the extremes. It is silly to say "regardless of the distribution" and then rattle off a set of characteristics of the distribution. It ain't "regardless" if you demand they "concentrate values around the nominal." Yes it is. You are totally wrong here. This is my main point. Think again, keeping in mind that I am not assuming a bell-shaped original distribution. I do not mean that the mean value becomes the nominal, only that it moves closer to the nominal. Assuming distributions when none is specified can lead to disappointing surprises. You've said that so many times it's stopped making sense. And yet you keep assuming distribution characteristics. There you go again. You deny it, then repeat it. Now, if you were hand selecting a tighter tolerance from a lower tolerance batch then pairing them might improve your yield because there might be more 'good' combinations of offsetting pairs than solely single values, if the unknown distribution allowed it. But, then, you can't necessarily count on that. (the manufacturer can because he knows the distribution) Yes you can count on it. Show me *any* plausible distribution where it would not be true. Now you are just making things up. A process that tends to produce product skewed to one end. Not plausible. But all the same, a compound resistor from such a set would be more likely to be closer to nominal, assuming any plausible skewed distribution. You would only be correct if it was skewed to the extent that *all* values were equally skewed, in which case all compound resistors would also be equally skewed. But that would not be a distribution, and is not plausible anyway. I'm not saying resistors are made that way but simply that you are ASSUMING distribution characteristics. And you may be correct but it has not one thing to do with a tolerance specification. Sigh...shouting what you denied again. Lastly, to cover the subsequent message, tolerance is the initial tolerance, at 25C, as delivered to your doorstep and before you begin torturing the thing. Everything else, solder, lead stress, temperature coefficient, long term drift, surge, voltage stress, temperature cycling, etc. are in addition to the initial tolerance. What subsequent message? Anyway, if you are correct here (evidence?), http://www.universalimport.se/Mfr.pdf "Tolerance The tolerance is the permissible relative deviation of the actual resistance from the nominal resistance value. It only refers to the possible deviation as received. It does not bear any indication whatsoever on possible changes of resistance under operating conditions." This doesn't quite make sense...aren't deviations always relative? So what is a "relative deviation"? Neither does it say whether confidence limits rather than absolute values would be "permissible". Anyway, like I have said so many times, I conceded the point that tails are chopped before your first post. This quote is mainly about Phil's point about service life. then it does at least mean that it is *possible* they chop the tails. Altogether you have been quite convincing on that issue...but where is your evidence? I haven't the slightest idea how you came up with the notion I've said one thing whatsoever about "tail chopping." Distribution tail. You should have sussed that by now. Your tiresomely-repeated point about tolerance being an absolute limit implies that distribution tails have been removed by measuring and discarding out-of-band resistors. cheers, Ian |
#24
|
|||
|
|||
"flipper" wrote in message ... : On Fri, 7 Oct 2005 17:29:31 +1000, "Phil Allison" : wrote: : : : "flipper" : : The tolerance number assumes nothing; : they'll simply be within 1% ... : : ** WRONG. : : You need to learn a new word. : : : ** You need to go get ****ed - psycho. : : : New Metal Film resistors are and need to be well within the 1% error : maximum : to allow for aging. : : Sorry, but no. : : : ** Prove it. : : With real data. : : : I did, below. : : ** That is NOT my experience over 40 years of dealing with the critters. : : I don't know what you think your experience has been but the : specification for tolerance is initial at 25C and the rest are : add-ons. Always have been. : : : ** Crap. : : For example : : http://www.universalimport.se/Mfr.pdf : : : ** Meaningless. : : : : .......... Phil Who'd have thought a 1 W resistor could lead to such heated argument :-) Where to get is off the screen. Just measured some 156 56K 1% BC (Philips) metalfilm resistor values. Result: Avg 55,86 K Max: 56,26 K Min 55,69 K average is 0,25 % off, 95% are within 0.6 %, all are within -0.6..+0.45 % Since they are on a (much longer) roll, it's interesting to see the values in sequence. It suggests a production process with upper and lower trigger levels changing some production parameter , ie. values are continuously measured and fed back into the manufacturing process, hence some 'extreme' value on the roll will give a 'swing of values' into the other direction and vice versa, some kind of noisy oscillation around the mean value. From this, it doesn't seem likely such a low cost product as a resistor is scrutinized for possible 0.1 % values, a separate more controllable production process for those makes more sense. It's just one batch, but measurements seem to bear out Phil's statements, in this case Rudy |
#25
|
|||
|
|||
"Ruud Broens" http://www.universalimport.se/Mfr.pdf ** Meaningless. .......... Phil Who'd have thought a 1 W resistor could lead to such heated argument :-) Where to get is off the screen. Just measured some 156 56K 1% BC (Philips) metalfilm resistor values. Result: Avg 55,86 K Max: 56,26 K Min 55,69 K average is 0,25 % off, 95% are within 0.6 %, all are within -0.6..+0.45 % Since they are on a (much longer) roll, it's interesting to see the values in sequence. It suggests a production process with upper and lower trigger levels changing some production parameter , ie. values are continuously measured and fed back into the manufacturing process, hence some 'extreme' value on the roll will give a 'swing of values' into the other direction and vice versa, some kind of noisy oscillation around the mean value. From this, it doesn't seem likely such a low cost product as a resistor is scrutinized for possible 0.1 % values, a separate more controllable production process for those makes more sense. It's just one batch, but measurements seem to bear out Phil's statements, in this case ** Now that is " real data " and confirms my experience exactly. The main production variable is imperfect consistency in the metal coating applied to the ceramic tubes - it they were all perfectly identical, the lathe that cuts the spiral in the surface would not need to measure each one as it worked. Thanks for those figures - Rudy. .......... Phil |
#26
|
|||
|
|||
Dope mcSmoke wrote:
Phil Allison wrote: "Dope mcSmoke" Phil Allison wrote: ** Use two 0.5, 0.6 or 0.75 watt 1% MF types in series. That'd be like a 1W 2% resistor ** WRONG !!! Even if *both* resistors were 1% high, the series value is also 1% high. Using resistors in series or parallel IMPROVES the % accuracy of the final value. ........ Phil Thinking about it now I realize that: two 1% 100R in series being 1% off could make 2*99R=198R or 2*101R=202R which is still 1% off, so you're right. But you still don't have to be a total bitch about it. Yes he does, He's incapable of anything else. |
Reply |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
Low noise resistors | Tech | |||
Carbon Resistors effect on tone | Vacuum Tubes | |||
Glass resistors? | Vacuum Tubes | |||
Fisher 400 - Output tubes: resistors - supposed to be there? | Vacuum Tubes | |||
Capacitors and Resistors | Pro Audio |